August 31, 2017 • 55 mins
Join Robert and Joe as they explore the world of green beard genes and their role in biological altruism. The Stuff to Blow Your Mind podcast takes you from the writings of William D. Hamilton and Richard Dawkins to laboratory results entailing ants, slime molds and rodent sperm trains.
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Speaker 1 (00:00):
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(00:46):
Stuff to Blow Your Mind from How Stuffworks dot com. Hey,
are you welcome to Stuff to Blow Your Mind? My
name is Robert Lamb and I'm Joe McCormick and Robert
I got a question. How often do you have this
experience of finding out one subtle way that somebody is
(01:08):
like you, and it's suddenly changing your whole attitude toward them.
So you're talking to somebody new you haven't met before.
You know, you're getting to know somebody who's been an
acquaintance and you find out that they really like one
movie that you like, or they really or they've traveled
(01:28):
to one place you've traveled to, or something like this,
and suddenly your brain just unlocks and you say, oh, okay,
we're cool now. Yeah, I encountered this a lot. You know,
they'll be I tend to be a little you know,
distrusting of new people and uh. And then sometimes you know,
you get to talk to them a little bit, or
you check out their social media activity or something in
(01:50):
your lies. Hey, they they really like this film, or
they they really like this artist that not many of
us are into, or they're into this h this other
a kind of niche thing that I love and there
and then you you you sort of give them the
benefit of a doubt based on that information. You're like, well,
they're they're probably pretty good, they're probably pretty cool, Like, babe,
(02:10):
I should talk to them a little bit more. What
else are they into that I like? But why why
is that? I mean, why is it that just using
like a shared favorite movie for example, Like what basis
do you have for thinking that somebody who likes the
same movie you like is a good person. Well, it
falls apart under the scrutiny of other things, because, for instance, um,
(02:33):
I'll use Tool as an example. Tool is one of
my my my favorite bands and Uh and their band
I loved in in high school and I've never I've
never stopped loving. There's been a lot of bands that
a lot of musical styles that have sort of come
and gone that I'll rediscover and and or that I'll
hate for a little home. But but but I've always liked Tool.
So what you're saying is the best rubric for discovering
(02:55):
whether a person is good or not is do they
like Tool? Yes and no. So, for instance, here at work,
Nathan our our our social media guru, uh, shortly after
he started, he saw that I had some some Tool
memorabilia at my desk, and we instantly struck up conversation
about it, and that was like our initial uh uh,
(03:16):
you know, bonding moment, or the fact that we both
like this group. On the other hand, I've gone to
enough Tool concerts to witness people that are also fans
of Tool and sometimes interact with them where I end
up getting a bit judge, and I think to myself, well,
there's no there's no way that they are appreciating this
music on the same level that I am. So it
(03:40):
can kind of cut both ways. You can be very
choosy about about how you feel regarding other people's appreciation
of your stuff. But ideally it would mean that if
if someone else is into something that that the that
you dig, then they're they're going to be into some
of the same ideas, some of the same values, some
of the same you know, aesthetic quality days what have you,
(04:01):
that that there's going to be more than just this
one thing that lines up between the two of you, right,
But you're using that one little detail, that one tiny
thing is some kind of like totem. It's this one
it's the signifier, this tiny flag flying above their head
that you have decided, for whatever reason, is good enough
(04:21):
evidence to open yourself up to this person and essentially
give them a fair shake that you might not give
to any other stranger. I've caught myself doing the same
thing too, even though I realized it makes no sense.
I mean, I think generally that you might be able
to make some kind of case that in some cases
(04:43):
shared aesthetics or shared values. Uh, you know that if
you like the same movie as somebody, it might embody
some kinds of values or intellectual predispositions that you would
find in common with other people who tend to like it.
But a lot of times that's not the case. I
don't know. I mean, I love Blade Runner, but there's
probably a lot of people who love Blade Runner who
(05:03):
are just absolute vampire. You saying they don't appreciate it
on the same level as you. Maybe that's it. I
wonder if you don't appreciate it on the same level
I do. I don't know. I've I've actually spoken about
this a little bit, but my thoughts on Blade Run
are mixed. But I do I do. I do love
Blade Runner. So today we're gonna be talking about a
(05:24):
hypothesis in genetics and genomics that is going to be
a kind of weird analogy to the personality tests that
we've just been discussing, and it's the concept of green
beard genes or the green beard effect. Now that the
sad news is that this episode does not really deal
(05:45):
with actual green beards. If you're looking for if you go,
if you're coming into this expecting an episode and a
weird genetic anomaly that makes people grow green beards, or
say a famous pirate with a green beard. Um, you're
gonna be disappointed on those counts. But the but the
underlying science we're going to discuss here in the genetics
is pretty amazing and pretty fascinating. Now I wanted to
(06:06):
come up with the backstory of the pirate green beard.
I couldn't think of what it is. What it's like
he's got algae in there or something. He just never
cleans his beard. Yeah, you're just um, I'm guessing you
probably have like really green teeth as well, you know,
and just maybe he eats a lot of plant matter
and it just kind of drolls down in his unwashed beard.
But you know, this does bring if there was if
(06:27):
there was a pirate with a green beard and he
met another pirate with a green beard, perhaps he would
have this effect. He would say, look, there is another
pirate who shares my esthetic qualities, perhaps my diet. Maybe
we have more thoughts on hygiene. Yeah. So the name
of the green beard hypothesis, which we will explain, comes
(06:47):
to us from Richard Dawkins, based on an example he
used to illustrate the concept in his nineteen seventy six
book The Selfish Gene. But the idea goes back to
the influential English biologists of the twentieth century W. D.
Hamilton's um And so the idea arises in the context
of a question about explaining how biology creates social behavior. Now,
(07:12):
this is one of the biggest, most difficult questions in biology, right,
So humans and other animals display these complex things like culture,
like aesthetic preferences, taste, uh, social behavior, all these things
that are complicated and have all these weird semi coded rules,
(07:34):
and we know at some level must be at least
semi dictated by genetic predispositions. But it's hard to know
what parts of culture and behavior are genetic and what
parts are just happenstances that you know that that arise
naturally and somewhat randomly. Well, we have all these levels
of cognition and culture that are kind of an illusion
(07:57):
and and and they're they're overriding the biology. But since
we are the illusion, it's hard to it's it's often
hard for us to really think about and in terms
of underlying biological properties. Yeah, so let's let's explore this
question that this problem with explaining social behavior through biology.
So we all know that species arise from the propagation
(08:17):
of self replicating molecules like DNA, the fundamental units of
heredity and DNA or genes. These are the parts of
your DNA that do something that are inherited from your parents.
And because genes make copies of themselves, we find some
of the same genes spread out across many different organisms
in the same gene pool. Now, obviously, genes that cause
(08:40):
an organism to die immediately at birth become less numerous
and eventually disappear. Genes that help an organism survive and
produce more offspring become more numerous in the gene pool.
These are the fundamentals of evolution by natural selection. This
is basic stuff. We we know it up to this point.
But here's a question. Why would an organism produced by
(09:01):
this process, that arises out of evolution by natural selection
ever displayed behaviors that we would call selfless or generous
or altruistic, for example, things like sharing food with another
organism or defending another organism in a fight. Now, I
do want to heavily qualify that by saying I think
(09:23):
It's probably not hard to explain why humans in particular altruistic, because,
after all, there appear to be a lot of ways
in which our complex brains can generate motivation for behaviors
that run contrary to our genetic fitness, and the simplest
example one of thousands would be celibacy. Whether for religious
reasons or philosophical reasons, or simply out of personal preference,
(09:47):
some people voluntarily choose never to have sexual relationships. This
runs absolutely counter to our genetic programming. Another more common
example would be the use of contraception. Many people who
are sexually active still choose to have no children, or
choose to have far fewer children than they technically could,
for a variety of reasons. So obviously there are some
(10:10):
ways in which the complex human brain has acquired the
capacity to override the genes that programmed it well, I think.
One one example that comes to mind is say, for instance,
my own son UH has adopted and so he is
not my biological offspring, but he he fulfills all the
needs and desires that that I had that I have
(10:30):
as a human for for offspring, for a son, right,
your genes don't care about him, but you do. Uh,
it's it's there in your brain, it is there in
your personality. So if you were only wondering about humans,
it might not be so hard to explain why we
would share scarce resources with a stranger, or risk our
own safety to intervene in somebody else's defense, or any
(10:53):
number of other selfless acts. We're smart enough to recognize,
maybe philosophical or religious reasons why we think we should
to help other people and override those selfish instincts to
act on those reasons. Or if you look at it
from another angle, maybe the more cynical person would say, well,
our complex, language obsessed brains are highly vulnerable to memes
(11:13):
that have the power to override the optimization of our
genetic fitness. Either way, human mentality appears to be fairly
unique on Earth, and it can account for behavior that
you wouldn't expect to find in other animals. But altruism
isn't only present in human beings with their religions and
moral philosophy and complex cognition. Altruism seems to be robustly
(11:36):
observed in other animals, from like complex mammals all the
way down to insects. Right, yeah, yeah, we have. We
have a few I think very illustrative examples here to
run through. Here's a crazy one. Vampire bats will regurgitate
blood for other bats who were unable to find a meal,
sacrificing their own immediate nutrition to keep another bat in
(11:58):
their community from starving. And this has been documented since
it was discovered in the nineteen eighties by a biologist
named Gerald Wilkinson. And that that's no small feat because
these bats are sort of operating constantly near the edge
of starvation. As we've talked about before. You know, if
a vampire bat goes a few days without food, it's
in a bad place. It can it can starve um.
(12:21):
And so sharing food like this is a significant sacrifice
for the good of another uh not necessarily related bat.
And you have to ask yourself, would your friends and
coworkers be selfless enough to vomit up blood in your
mouth if you've missed a meal. None of them have
ever offered, And it makes me feel rather sour. But
it's not even just the mammals, right, We see classic
(12:43):
altruistic behaviors in in uh animals that are thought of
as less complex. Right, Oh yeah, I mean bees are
a prime example of altruism, and I mean you social
insects in general have pretty much perfected altruism in many respects.
So worker bee works for the benefit of the queen's
offspring while for going reproduction herself. Genetically speaking, she is
(13:08):
not the genetic future the hive. The queen is, the
drones are, but the workers do all the work. In
a weird way, you can almost think about the insects
like this, being that the queen is the organism and
the worker bees are like fingers or appendages of the
major organism. Yeah, exactly, and it's just completely completely selfless
(13:28):
if you look at it from the right angle. Yeah,
but how about birds too, well, ravens who we've talked
about ravens a bit when we talked about bird intelligence. Uh,
Ravens have been observed to call in additional ravens when
they happen upon food, so like a mouse or something,
which doesn't make any sense that they have it, but
they have apparently have a special call that they use,
(13:51):
so they raise the alarm and say, hey, other ravens
that are not me or my children, come in here
and get part of this mouse. Why would you do that?
It doesn't seem to make sense. But some ravens even
return to their roost and recruit more eaters to come
and share in the feast. Yet again, so your friends
and co workers, they've never offered to vomit blood in
(14:12):
your mouth. They've also probably never offered to share a
dead mouse with you. Well, no, but on the rare,
on the on the instances where we've had catered dead mouse, Uh,
then it certainly people will come around and say, hey,
there's food on the question mark table, come and eat
with us. So, well, that's just their moral philosophy or
their religion or whatever. Alright, Well we have some some
(14:36):
other just quick examples throughout. Dolphins and elephants are fairly
complex social animals and display uh various forms of altruism.
They form social bonds, and then then they seem to
make conscious decisions to help members of their group. Yeah,
and so we have all these examples of these are
by far not the only examples. There are just tons
of documented examples of animals in the wild or in
(15:00):
a conditions seeming to help other animals who are not
their direct offspring at their own at their own expense.
And obviously we can see why evolution would select for
genes that cause organisms to be altruistic towards their own children. Right,
that's kind of the whole point. Your genes optimize your
body to have lots of children that can carry as
many copies of those genes into the future as possible.
(15:23):
But why would evolution produce creatures that sacrifice some of
their own safety or resources to help save another creature
that wasn't their direct offspring? I mean, wouldn't wouldn't genes
that promoted selfishness and cowardice produce the most grandchildren on average? Well?
I mean one obvious answer here is that there's an
(15:43):
individual survival advantage in groups, right, Right, The group kind
of becomes the meta organism, and natural selection encourages the
pro group members of the metal organism and not and
not the lone wolves. Now, this is attempting direction to
go in, but there are critic of this type of thinking,
So lots of scientists have tried to go in this direction,
including EO. Wilson in later years. Uh. And this is
(16:06):
sort of related to the concept known as group selection. Right.
The idea that natural selection can select for not just
the survival of individual genes or the survival of individual organisms,
but groups of organisms together. This is also known as
multi level selection. But, like I mentioned, this idea has
a lot of harsh critics, including Dawkins. I mean, he's
(16:29):
criticized this idea. And here's one potential snag. It's true
that teamwork pays off, right, But you know what pays
off even more than teamwork? Letting other people do the
team Ah. This is the This is the classic um
A classroom situation where you've been assigned to groups and
you're gonna have somebody in the group who's a real
(16:50):
hard work, are very dedicated. You have some other individuals,
and you can have at least one person who's just
gonna coast right right, Yeah, So you let the rest
of the team do the work while you sand bag
and reap the rewards. So if you imagine if you've
got wild dogs that have a gene that causes cooperative
pack hunting behavior where every dog chips in and does
their share of work in the hunt, and in turn,
(17:12):
this increases the group's chances of catching prey and then
they all share the benefits. That would be great. Everything's
going great if you've got dogs with those genes, But
then one of the dogs in the pack acquires a
mutation that says, actually, don't help with the hunt, just
hang around until your pack mates catch something, and then
show up and plunge your face into that delicious viscera.
(17:35):
A dog with this trait would spend less energy hunting,
and it would risk less injury, and it would still
get the rewards of the hunt, so it would ultimately
benefit more than any of the team players, and on
average that that freeloader dog would have more offspring, meaning
that over time the freeloader gene would become more common
than the team player gene, and the pack hunting system
(17:58):
would sort of fall apart. So systems that rely on
benefits of group cooperation for the sake of the group
as a whole are sort of pervasively undermined by the
interests of individual organisms and individual genes within the group,
which will sort of inevitably find ways to run counter
to the success of the group as a whole. So
(18:20):
to sum up, we can show that in general, natural
selection will tend to push organisms to favor their own
success at the expense of others and at the expense
of their groups. And yet at the same time, group
cooperation and selflessness is present in nature, so there must
be some way to reconcile these observations, right, yes, and
I imagine this is where the green beard comes in. Well,
(18:42):
the green beard is going to be one weird way
of branching off of this question. Actually, the main answers
to this question are not going to be the focus
of today's episode, but we should mention them. So two
of the main answers that emerged in the twentieth century
to answer this question, or what's known as kin selection
and what's known as reciprocal altruism. So reciprocal altruism is
(19:03):
basically another way of summing it up, is just the
phrase tip for tat. And while in many cases it
can be hard to verify outside of lab conditions, you
can sort of build models of organisms that behave on
this principle and it does appear to be stable if
and the way this works is like this, So if
a member of the pack is mean to you, or
(19:23):
if they try to cheat and be selfish, you repay
them back the same way you're mean to them back
you you don't share with them. But if another member
of the pack is nice to you, you're nice back.
So essentially you just mirror. You start with the basis
of being nice, and then you mirror the you mirror
the behavior that people display towards you. Okay, well that
(19:45):
that makes sense. I think everybody can fall fall behind that. Yeah.
And if you run models like this, it is mathematically stable.
Genes that encourage this type of behavior don't tend to
get eliminated from the gene pool, but they can reach
a kind of stable equilibrium. But the other main idea
is what's known as kin selection, and this was explored
in the nineteen sixties by the English biologist we mentioned earlier, W. D. Hamilton's.
(20:09):
Now Hamilton's used these quantitative genetics modeling methods, which is
like math about how genes are inherited and distributed to
show something interesting, It makes mathematical sense for genes to
optimize for altruism toward blood relatives other than our own offspring.
So it turns out that for a sexually reproducing species
(20:31):
like us, you share the same percent of your genes
with each of your children that you do with your
full brothers and sisters and with your parents. In each case,
you share fifty percent of your genes with them, and
to a lesser extent, the same goes for other members
of your family. Further removed, you'll share more genes with
your aunts and uncles and nieces and nephews than you
(20:52):
do with the general population and so forth. And given
this calculus, you can work out how genes that direct
organisms to be generous and altruistic toward family members become
more numerous in the gene pool than genes that direct
organisms to be exclusively selfish and unhelpful to anybody. So
if I have a cousin that appears on America's Got Talent,
(21:15):
I'm going to root for them in part because they
share more of my genes than anybody else that's contestant
on that show. I mean, on average, they probably do.
You might have like a secret unknown brother or sister,
but yeah, yeah, on average, that's going to be the case. Now.
And of course, there are lots of weird ways that
maybe things like kin selection or reciprocal altruism uh could
(21:39):
be could be sort of modified in various circumstances to
generate the mechanisms that create altruism that get applied in
other ways. But it is in the context of discussing
this this whole question about altruism and biology in the
Selfish Gene that Dawkins also came up with this weird
hypothetical idea for one weird type of selective altruism, the
(22:03):
green Beard. All Right, we're gonna take a quick break
and when we come back we will join back up
with Captain green Beard and discuss the details of of
of this idea. Alright, we're back. So we were mentioning
how the name of the green Beard gene comes from
(22:24):
an example given by Richard Dawkins in The Selfish Gene
in n So, Dawkins is pointing out how any arbitrary
gene will become more numerous if it makes carriers of
that gene friendly and helpful toward other carriers, right, and
that sort of makes sense. It says like, if you've
got gene A in your body, gene A does especially
(22:45):
well if it makes your body give food and night,
you know, nice behavior toward other carriers of gene A. Right,
it's just a boost for gene A across the board.
So he starts talking about the example of the gene
for albinism, which is a genetic condition that causes the
carrier to have unusually low levels of the pigment melanin,
(23:06):
leading to paleness of skin, hair, and eyes. And hypothetically,
a really successful version of this gene for albino traits
would not only produce the visible traits, but it would
motivate a carrier to be helpful toward other people who
have these visible traits. Now keep in mind, this is
not how the albino traits work in in reality. This
(23:29):
is just a hypothetical alternate version of them um And
if this were to exist that way, everyone who has
this particular gene would have more offspring and the gene
would become even more abundant. But would we find something
like that in nature? That's the question, and Dawkins writes
the following quote. It is theoretically possible that a gene
(23:49):
could arise which conferred an externally visible label, say a
pale skin or a green beard, or anything conspicuous, and
also attendance to be specially nice to bearers of that
conspicuous label. It is possible, but not particularly likely. Green
beardedness is just as likely to be linked to a
(24:10):
tendency to develop ingrown toenails or any other trait, and
a fondness for green beards is just as likely to
go together with an inability to smell frieze is it
is not very probable that one and the same gene
would produce both the right label and the right sort
of altruism. Nevertheless, what may be called the green beard
altruism effect is a theoretical possibility. So this is where
(24:35):
the green beard idea comes from. And to be clear,
Dawkins is not saying that he expected to find anything
like this in nature, right, I mean, it would be
it would be a tough sell to say that there's
just one gene or one tightly linked group of genes
and that does all that work. It's got to produce
the externally detectable trait. It's got to detect that trait
(24:56):
in other people, and it's got to make you a special,
really nice or in some way manage a positive interaction
with other people who have that externally detectable trade. And
uh so, so he wasn't saying you'd expect to find it,
just that it was an interesting hypothetical possibility, Like he's saying,
it's possible that the murder was committed in the library
(25:18):
with the candlestick by Colonel Mustard with a green beard
by Colonel ver dear Beard. But but it's just a
hypothetical situation, Yeah, and one thing one that would be
difficult to come about. But if it did exist, it
would be encouraged by natural selection. Right, he's sort of
pointing out how natural selection would favor this. You just
wouldn't expect it to arise in the first place. But
(25:41):
nature is stranger than our imagination. Ah, and this is
where we get into actual examples in nature, the green beard.
So this was not what we originally expected, right, I mean,
geneticist didn't think that you you discover things like this
in nature. But man, the actual world is always surprising us.
(26:03):
So let's meet a species. Solenopsis invicta. It sounds pretty serious,
it sounds pretty pretty indomitable. It's like the it's like
the you know, the Roman Emperor species, And it kind
of is because that is the name of the red
imported fire ant, which is native South America. It has
spread everywhere from Australia to Asia, the United States. It's
(26:26):
all over the place now, and woe to us for
that fact. They were first introduced to the United States
sometime in the nineteen thirties or forties, and now they
are known as an invasive pest with hot needle venom
and a ferocious fighting response when their nests are disturbed.
In fact, in our episode about the biophelia hypothesis, we
talked about that great video of EO. Wilson trudging through
(26:48):
the woods until he finds a red fire ant nest
and shoving his hand into it so he can show
you how much it hurts. Oh, yes, this is this
wonderful footage. I love that he just he stirs them
up less and krawling hand lets them sting him in
almost like a religious moment. For Yeah, he's so happy
about it. If only people in general could find something
that they love as much as this man loves these
(27:10):
ants that are furiously pumping their venom into his body. Anyway,
another perhaps interesting thing about these fire ants they exist
in two sub populations. So they've got so they've got
this species, and then two subpopulations have very distinct ways
of making a living. One tolerates only one queen per
colony and the other has multiple queens per colony. Uh,
(27:34):
and those are known as the mono guy in versus
the polygone types. You know, one one queen multiple queens.
So in Lauren Keller and Kenneth g Ross published an
interesting report in Nature about Solenopsis invicta, and Keller and
Ross were studying red fire ants of the polygone variety,
that's the kind that has multiple queens. So within the
(27:57):
genome of these polyguine sol Anopsis invicta, there is a
gene locust called g P nine and a couple of
terms to explain real quick. In genetics, a locus is
just the location on a chromosome where you know you
can look to find something, where you know you can
look to find a gene or one of its alleles.
And allele's are variable forms of a gene appearing at
(28:21):
the same locus. So, for a simple example, at the
locusts q x one, you might contain a gene that
regulates the speed at which your toneails grow. And if
you have one allele at q x one, your toneails
grow fast, and if you've got a different allele at
q x one, your tone nails grow slow. Now back
to the fire ants. They've got this gene locust called
(28:42):
g P nine with two allele's big B and little B.
And because they have two sets of chromosomes. The ants
can have three different types of arrangements at g P nine.
They can have big B, big B, Big B little
B or little by little by. All right, now, if
you were to watch these colonies up close, where a
(29:03):
new queen reaches sexual maturity and starts trying to mate
and lay eggs, you notice something weird. Only the queens
with the two different alleles, the big B little be
jeans at g P nine live long enough to reproduce.
Why is that what happens to the others. So first,
it appears that queens with little be little bee die
(29:24):
very young of natural complications. This just appears to be
a lethal recessive combination. And we see this a lot
of times in nature where if you've got two copies
of this recessive gene, it's it's bad news for you
and it can lead to a genetic condition that kills you.
But what happens to the big B big B queens. Well,
Keller and Ross found out they get violently executed by
(29:47):
their own workers. The ants of the colony tear their
soul apart. So furthermore, they discovered that it was primarily
workers bearing the little bee allele that did the any
work of killing the queens without it. So if you've
got a queen that's big B big B, the workers
that have a little bee allele will surround it, bite
(30:10):
it and kill it because it is it's essentially in
some respects, it's like a foreign queen. It does not
share the same allegals as it does. Yeah, that's what
appears to be going on. But how how does that happen?
I mean, normally you wouldn't be able to look at
somebody and say you're missing one particular gene that I
(30:32):
have and I'm going to kill you. So what's going on?
So the worker ants with that little bijeene at g
P nine tend to violently massacre any potential queens that
don't carry the little bee gene at g P nine.
Uh So it sounds like we might have a slightly
modified version of the green beer gene on our hands.
But here's a question. How how do those workers know
(30:55):
when the new queen has the right a leal or not?
Here's a clue. The author's noticed that sometimes after a
worker ant took part in a mob executing a big
B big B queen, the worker aunt would then be
attacked by other ants in the colony. So you take
part in the mob, you kill that big Bi big
(31:15):
b queen, then you walk away. Then other worker ants
kill you and you know it. And there's no politics
in the insect world, so you know, it's not just
some sort of a situation where the assassin has to
absorb the blame for the regicide, right right, right, It's
not like the king slayer is now being you know,
talking to me, like, so what was going on? You
(31:36):
have to wonder was something rubbing off on the killer
worker And this led the authors to suspect the culprit
is pheromone based. So they tested this by rubbing worker
ants against two different types of queens, the big b
big be queens and the big Bee little bee queens,
and then releasing those workers to their colleagues, and sure enough,
(31:57):
the the other workers tended to a hack the ants
that have been rubbed against the doom big Bi big
Bee queens, but not against the queens with a copy
of the little be allele. So to know that we're
looking at an actual green beer gene, we've got to
remember the gene should be doing three things. It's got
to produce an externally detectable trade. It's got to detect
(32:18):
that trade and other individuals, and it's got to provide
preferential treatment to individuals bearing that trade. So it looks
like maybe maybe what's going on here is this ants
with the little bee gene at g P nine will
attack and kill anything that smells like a sexually mature
queen unless it also carries the chemical signature generated by
(32:41):
the little bee gene, which switches off that kill drive
in the workers. Interesting. Okay, so this looks like, if
these findings are correct, a genuine green beer gene found
in nature, there's this one gene or some incredibly tightly
linked group of genes going off the g P nine locusts.
(33:02):
That says, if the queen doesn't have this one gene
killer al Right, well, we're gonna take a quick break
and when we come back, we have some more possible
examples of the green beard gene going on, and we
will talk about the wood mouse and the sperm train.
(33:23):
All right, we're back. So, Robert, you promised before we
left that you were going to tell me about sperm trains. Yes,
Uh so I'm gonna gonna go ahead and back up
here a little bit for everybody before we get into
just you know, full on with the sperm train. If
you were like us, then you've probably read and viewed
a great deal of science content about sperm over the years. Uh.
(33:45):
This is a topic that pops up in nature documentaries,
science news articles, and seemingly endless academic papers. Well, the
sperm it kind of creates a microcosm of the whole
natural world, right, Yeah, it is because you know, it's
a situation where when when the sperm are competing against
each other to go after the goal that's happening on
the inside. On the outside, of course, we have all
(34:06):
these various uh mating competition scenarios that factor into our
nature documentaries, you know, where different males are competing uh
to mate with the female, or multiple males mating with
the female, what have you. Uh. So it's interestingly we
have kind of this outer war of mating war going on,
and then there is an intermating war as well. Because
(34:28):
we have all these examples of of sperm uh playing
a role in this outer war. We we learned, um,
you know, the violent details of copulation and how sometimes
they can deter females from acquiring additional males um. There's
also the interesting hypothesis regarding Kama kaze uh spermatozoa in
rats and humans, with the hypothetical primary function in these
(34:52):
particular sperm of incapacitating sperm of arrival male. It's kind
of like dog fighting sperm or It also makes me
think of say a miniature Star Wars space battle taking
place inside and that the egg is quite ironically the
death star maybe the life star. Well yeah, if you're
a sperm, you don't want to blow up the egg.
(35:13):
You want to join in harmony with the egg. Well yeah,
but but but you have that one individual sperm wants
to do it, and it's it's it's a race. It's
a competition life star like that. Yeah, now you kind
of grow used to this trend, right, there's competition, ruthless aggression.
Sperm is the life seeking missiles at war with their rivals.
Multiple matings resultant sperm competition and even mixed paternity. But
(35:36):
sperm are also competing against all of their their brethren. Uh.
And therefore it's a bit shocking when you realize that
there are cases of sperm cooperation. So most examples of
this occurs in the let's face it, freaky world of mosques,
as well as the the aforementioned politics free realm of insects.
(35:56):
But there's actually an example in the mammal realm as well,
as demonstrated in the two thousand two paper. And I
love this title, exceptional sperm cooperation in the wood mouse
exceptional A plus sperm cooperation. So the wood mouse this
is a you know, a Western European rodent. It's small,
but it has tremendous sperm output. The mice in general,
(36:20):
uh that they have rather large test these tests or
five percent of their body. And if we were if
this were the case with humans, to put that in perspective,
a male human would have seven points points seven pounds
or three point five ms of tests. So these uh,
the fact that they're over sexed, it would seem this
(36:41):
is helpful because they engage in quote scramble competition, uh
to mate polygamously with promiscuous females. As such, you would
expect a lot of sperm competition going on there. Race
to the life star. And this is where the train
comes in because the wood mouth sperm feature quote extremely
(37:03):
long apical hooks and they use these hooks to form
together into a store to sort of think of it
as a sperm vultron, or, as the paper puts it,
motile trains of spermatozoa comprising hundreds to several thousands of cells.
These trains these sort of you know hooked together, you know,
(37:25):
wheels of sperm. Uh. These trains allow the bound sperm
to travel at greater speeds up to fifty faster than
loan sperm out there going on their own. But as
they do that, they've got to be given a leg
up to these other sperm that they're in competition with.
That's the thing, because ultimately only one sperm can get
(37:46):
in there. But they're they're all working together. It's it
makes me think of these scenarios where a bunch of
villains team up, uh, and then they're all going to
turn in turn on each other at the end, but
for a little while they're working together, like a sinister
six situation. Right. I thought you were going to say
suicide squad. Well, I guess that's a similar example. They're
all villains, right, are they so untold? I I didn't
(38:08):
see it. I I tried to check it out on HBO,
uh to see what everyone was talking about and made
it made it just about like five minutes in. But
maybe it's a great film. I could be wrong. So
in these cases, the hook up occurs one to two
minutes after ejaculation, and that's when head to head or
tail tail to head hookups occur. So they have hooks
(38:29):
on their heads as well in this scenario. But again,
only one sperm may enter the life star. It's it's
it's like the scene with the you know, trying to
shoot the bolts into the death Star. Uh. So the
train starts to decouple about twenty to thirty minutes after forming,
and in doing this, many of the individual sperms seemed
to sacrifice themselves and uh and some might be even
(38:51):
marked for death ahead of time, or there might be
competition there at the end. So again, think of a
group of supervillains. They've they've worked together so far, but
after they kill the Batman or the Superman, they're just
gonna turn on each other. So how do the researchers
connect this to the idea of the green beer gene. Well,
this is what they say. Quote a green beer gene
might evoke such cellular cooperation, although other genetic mechanisms cannot
(39:17):
be excluded at this stage. A green beard is a
gene that recognizes copies of itself and other individuals and
directs benefits to those individuals. So the idea, here's the
green beer gene would be the deciding and factor with
which sperm you're going to team up with in this battle,
because you certainly are not gonna gonna want to hook
up with sperm from other uh individual mice that have
(39:41):
made it with this particular female. Right. Interesting, So so
they're saying this could be one explanation of the behavior
they're seeing here. Yeah, this is Life Race two thousand.
All the cars are heading out, but some of these
cars are realizing that they can work together and form
a train uh to to to out maneuver and and
uh and and outperform their competitors because some of the
(40:04):
cars have exact copies of the driver in each one. Yeah,
like multiple Frankenstein's that was a deep cut. I scared
somebody off there. Roger Corman's Death Rays two thousand, if
you want to want to get all of that, Okay,
So that's another So there really does appear to be
a green beer, you know, if the observations are correct,
there really does appear to be a green beer gene
(40:25):
working in the fire ants. Uh. It looks like green
beer jeans are a good candidate to explain what's going
on here in the sperm trains, but it's not a
sure thing. Other mechanisms might explain it. In two thousand
and eight, I should just mention quickly there was one
paper that seemed to identify a green beer gene that
was driving cooperation in yeast cells, and that that gene
(40:49):
was called f l O one. But just recently I
was reading about how there is apparently green beer gene
activity in slime molds. Our old friends. Oh yes, yeah, yeah,
this was pretty interesting. So to refresh slime molds, which
which I like to compare to science itself at times.
I think it's a good metaphor for it. Slime molds
(41:12):
are microbes that live as single celled organisms, but they
kind of vultron together into a great communal metal organism
that quests after food. It's a two vulturo on episode. Yeah. Uh,
and you know, there's some fabulous experiments that show the
sort of communal intelligence that it has, like a very
non non non human form of intelligence. So it's problem
(41:34):
solving ability. Yeah. Well, in March of this year, geneticists
from the Universities of Manchester and Bath discovered that these
individual cells are capable of choosing who they joined forces with.
So it's not just you know, every um slime mold
individual is gonna come together like they're gonna be a
(41:55):
little bit choosy and uh. And it seems that green
beer jeans factor into it. Oh okay, So you're a
slime mold cell and you've got this one gene that says,
if there's another slime slime mold cell that has this
same gene, join with them and conquer the maze. Okay, yeah,
it's so it's pretty straightforward in that regard that the
(42:17):
gene in question encodes a molecule on the surface of
a slime mold cell and it can bind to the
same molecule of another slime mold cell. Now, most my
slime molds strains have a unique version of the gene. Okay. Now,
there's a great deal of diversity in slime mold green
beer genes, according to the study, but individuals show a
(42:38):
preference for cells with like or similar green beer genes,
and the assembled whole the resulting you know, larger mental
organism slime mold. Um, it actually performs better. It does
better if it's formed of preferred partners as opposed to
you know, non preferred partners. As such, these beer genes
(43:00):
listening to govern in a particular specific cooperative behavior in
the slime molds. So the way it works is it
just makes you sticky for other slime mold cells that
have this same gene. Yeah, basically like on a very
it's it's kind of just like the real pro gloves. Yeah,
it's like the simplified version of why liking the same
(43:21):
band um binds you to somebody else. So to summarize
going off the paper here, Uh, the green beer genes
achieved the following in the slime mold. So they predict
partners specific patterns of cooperation by underlying variation in partner
specific protein protein binding strength and recognition specificity. Uh. They
(43:45):
also increase fitness because they help avoid potential costs of
cooperating with incompatible partners. And also they generate a homophilic
binding spectrum that allows individuals to identify appropriate partners with
whom to engage in cooperation. And its states that it
also serves to stabilize cooperation in the face of selective
(44:08):
pressure for the emergence of quote false bearded cheaters who
by providing information that can be used to differentiate compatible
from incompatible partners. So this is a new ripple. This
is a new ripple. So we started with this hypothetical
idea that Hamilton and Dawkins talked about, saying that it's
(44:28):
not necessarily going to be found in nature. It's just
one hypothetical thing that could work if it ever were
to arise. Now we're finding examples of it in nature.
The green beard gene, the gene that says, hey, I
see you have this gene too. I like you. I'm
going to treat you right. But now we see that
there are false beard pretenders. You could have a gene
(44:48):
that in fact signals the same thing as having the gene,
or something that could easily trick you into thinking they
have the gene but they don't have it. Well, you know,
I'm reminded of the slime mold moving through the maize
that you know, our scientific uh quest to understand the universe.
So anytime we find something new, there's always some new ripple,
some new complication, uh. And and and some new level
(45:11):
of the complexity of life. So what is the what
is the liking the same band equivalent of the false
spirited cheaters? Somebody who you think signals liking the same band,
but in fact they do not really like them. Is
that the the fake tool fans you were talking about
at the beginning, maybe, or maybe a better example would be,
(45:34):
like there might be a band that was really popular
and you dig them, somebody else doesn't. Really they're not
They're not a true fan. They just they're maybe a
little nostalgic for it. Or they remember listening to this
band in high school. But where have they been, you know,
the subsequent decades. So they've got the bumper sticker on
the back of their car. But if you started talking
(45:56):
to them, you would find that the compatibility you were
seeking is not really. It's all superficial, right, or maybe
it's Uh. It also reminds me I think it was
Kids in the Hall skit where somebody's trying to buy
a copy of The Door's Greatest Hits at the CD
store and this guy comes in Elections and was like, no,
you have to start with the first album, and then
you have to listen to it, like there's very specific
(46:18):
instructions about where you listen to it, how long you
listen to it, and then only then can you move
on to the second album, and you have to go
in order. So he's instructing him how to be a
true long term fan and not like a cheap skip
to the greatest hits fan. How to be a true
pretentious jerk. Do pretentious jerks glom onto each other in
the same way that Greenbeard slime mold cells do? I
(46:39):
don't know, or maybe I mean I guess they do.
But you could also argue that they don't have the
binding factor. They're just too pretentious about their their stuff.
They can't actually enjoy it with other people because they
have to be the they have to be the biggest
fan in the room. They have to be the smartest
fan in the room. But we're getting into the human
complexities here of of of sharing and things. I think
(46:59):
we've run more fild with our metaphors and we've gone
off the deep end. Anyway, picking up from our intro
to this episode, where we had to lay the context
about the discussion about altruism and biology and the idea
about the different levels of selection I've been thinking that
this would be daunting because it makes biologists uh ruffle
(47:20):
their feathers and get very upset. I think maybe in
the future we should try to do a big episode
or maybe a two partter on the levels of selection
debate in biology, like this big controversy over whether group
selection is a real thing or not, or whether whether
there's also arguments about the arguments, like whether the argument
(47:42):
is real or whether it's just semantic um and so
I think I think there's a lot of interesting stuff there,
but I know it's a big, thorny, controversial issue that
has a lot of uh petty sub issues. Well, no,
that could be fun. I mean, who knows. Maybe it's
a topic that it would be Uh it would be
sensible to bring in a guest to help us and
(48:05):
navigate all the controversies. Well, maybe we need to bring
to two guests, one that take each side. Ah, and
then we turned into a debate show, but we're not
we're not going to do that. Well anyway, if that's
something you would like to hear, maybe you should let
us know. Yeah, yeah, for sure. Hey, before we close
out here, Uh, this is one of the first episodes
(48:26):
that we're recording after the total solar eclipse here in
North America. Uh And, as previously stated, you went up
to Tennessee to to check it out, to be within
the line of totality, and and I went up to
Blue Ridge, Georgia in the North Georgia Mountains and observed
it as well. So what are your thoughts? It was?
(48:49):
It was amazing. I was trying to uh convince everyone
that we should go up to the path of totality,
and they were like, but hey, isn't it like totality
here in Atlanta. And I was trying to explain the
difference between like ninety nine point nine and is is
apparently huge. And I'm glad we went. I'm glad we
(49:10):
did it. It's I don't want to sound flip when
I say this, but it was a religious experience. I mean,
it was a really truly astonishing thing. I've never seen
anything like it before. It was amazing watching all the
different physical changes going on around us. As the totality approached.
There was this moment where it was probably about as
(49:30):
the sun was about seventy covered, maybe a little bit more,
that I started to notice that there was still still
the appearance of sunlight all around me. So it was
like a bright summer day, but suddenly there was I
didn't feel the heat anymore. The sunlight felt cool, and
I could stand in the direct sun and my skin
didn't have that that radiation reaction it normally does when
(49:51):
you're standing out in the direct sunlight. There. I don't
know that. The colors became so strange as it came on,
and then once the totality hit it was true what
I read in advance that said, you know, it can
feel like it's over in seconds. It totally did. I
was just standing there gaping at it, and then I
after almost no time at all, it was over. Yeah.
(50:13):
I was really impressed by it as well. I mean,
aside from just the the the actual spectacle of the
full eclipse, just seeing the ring there in the sky. Uh,
you know, all the subtle stuff was very in a
way unnerving, and and and and he felt like you
were kind of crossing over into, uh, you know, an
(50:33):
abnormal realm because that you had this sense that it
was it was dusk, but there was no sunset on
the horizon, you know, there was this uh this also,
I certainly observed the changes in the animals because I
was in the forest in the mountains, So the cicadas
all died down, and it suddenly the cicadas stopped making
(50:55):
their noises and the crickets started up. Yeah, I observed
that too. Up in Tennessee. We heard the nighttime insects
begin to whir to life. Another thing when we saw
moths as well, Like suddenly there were moths flying around.
So I got to see because I knew in advance
to look to the west, like we talked about in
our eclipse episode, there were some clouds in the sky
(51:19):
to the west of where we were, and I kept
my eyes focused to the west right as the last
of the Bailey's beads were fading, and as it was
coming on, and I saw the shadow pass over the
clouds to the west of us, and it was so
cool to see like that, we had white clouds and
then suddenly black straight over them. And of course everyone
experienced the drop in temperature, but we also witnessed what
(51:41):
I believe was, you know, weather changes because of that,
because the it was a little bit cloudy, and the
clouds were on the just teasing with us with the
possibility of obscuring the total eclipse, but it held off.
But then right after the eclipse occurred and was and
and and the moon was big getting to move out
of the way of getting away again. Uh, there was
(52:03):
this um suddenly a lot of cloud cover moved in
and then it almost immediately started raining. Yeah. I think
we had some strange weather the rest of the day.
How about your dog, Charlie? Was he there? No, we
left him at home. I we thought about bringing him,
but the place we were going was it was a
college campus up in up In, Tennessee, and we didn't
(52:25):
know how many people would be there, and we didn't
want him to get upset if there was a big crowd. Um,
so we we just left him at home and he
was fine. Well, Uh, my son came. He really enjoyed it.
It was just a great experience. So uh, And I
know I reached out on the Facebook on social media.
A number of our followers there, our listeners there, they
(52:46):
chimed in those that either experienced the partial or the
total eclipse. And certainly we'd love to hear from anybody
else who has particular observations about how the environment reacted
or or how you reacted to the total eclipse. Uh,
you know, we would love to hear your experience as well.
One last thought, photos don't do it justice. Yeah, absolutely not.
(53:09):
I mean I've seen tons of photos of past solar eclipses,
but it's not like seeing it in person for yourself.
So if you ever get a chance in the future,
if you want to, you know, if you're in South America,
or you want to fly to where one of those
total eclipses in upcoming years is coming, or if you're
in the United States and you just want to go
ahead and start planning for it's really worth it. It's
(53:31):
something unlike anything else you'll see in your life. All right, Hey,
In the meantime, waiting for the as you wait for
the next episode of Stuff to Blow your Mind to
come out, head on over to Stuff to Blow your
Mind dot com. That's where you'll find all the podcast episodes,
including our episode on the on the the the solar
eclipse then that came out in the last week or two.
(53:52):
Be sure to check that out. Also, you'll find links
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hosts as well. And you can also just bring up
(54:15):
like cool ideas, cool articles, et cetera, and there'll be
some some other like minded individuals to bounce that off of.
And hey, if you want to get in touch with
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email us at blow the Mind at how stuff works
dot com for more on this and thousands of other topics.
(54:44):
Does it how stuff works dot com. He graduated in
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Comic Con dot com slash NYCC hyphen presents Welcome to
(00:46):
Stuff to Blow Your Mind from How Stuffworks dot com. Hey,
are you welcome to Stuff to Blow Your Mind? My
name is Robert Lamb and I'm Joe McCormick and Robert
I got a question. How often do you have this
experience of finding out one subtle way that somebody is
(01:08):
like you, and it's suddenly changing your whole attitude toward them.
So you're talking to somebody new you haven't met before.
You know, you're getting to know somebody who's been an
acquaintance and you find out that they really like one
movie that you like, or they really or they've traveled
(01:28):
to one place you've traveled to, or something like this,
and suddenly your brain just unlocks and you say, oh, okay,
we're cool now. Yeah, I encountered this a lot. You know,
they'll be I tend to be a little you know,
distrusting of new people and uh. And then sometimes you know,
you get to talk to them a little bit, or
you check out their social media activity or something in
(01:50):
your lies. Hey, they they really like this film, or
they they really like this artist that not many of
us are into, or they're into this h this other
a kind of niche thing that I love and there
and then you you you sort of give them the
benefit of a doubt based on that information. You're like, well,
they're they're probably pretty good, they're probably pretty cool, Like, babe,
(02:10):
I should talk to them a little bit more. What
else are they into that I like? But why why
is that? I mean, why is it that just using
like a shared favorite movie for example, Like what basis
do you have for thinking that somebody who likes the
same movie you like is a good person. Well, it
falls apart under the scrutiny of other things, because, for instance, um,
(02:33):
I'll use Tool as an example. Tool is one of
my my my favorite bands and Uh and their band
I loved in in high school and I've never I've
never stopped loving. There's been a lot of bands that
a lot of musical styles that have sort of come
and gone that I'll rediscover and and or that I'll
hate for a little home. But but but I've always liked Tool.
So what you're saying is the best rubric for discovering
(02:55):
whether a person is good or not is do they
like Tool? Yes and no. So, for instance, here at work,
Nathan our our our social media guru, uh, shortly after
he started, he saw that I had some some Tool
memorabilia at my desk, and we instantly struck up conversation
about it, and that was like our initial uh uh,
(03:16):
you know, bonding moment, or the fact that we both
like this group. On the other hand, I've gone to
enough Tool concerts to witness people that are also fans
of Tool and sometimes interact with them where I end
up getting a bit judge, and I think to myself, well,
there's no there's no way that they are appreciating this
music on the same level that I am. So it
(03:40):
can kind of cut both ways. You can be very
choosy about about how you feel regarding other people's appreciation
of your stuff. But ideally it would mean that if
if someone else is into something that that the that
you dig, then they're they're going to be into some
of the same ideas, some of the same values, some
of the same you know, aesthetic quality days what have you,
(04:01):
that that there's going to be more than just this
one thing that lines up between the two of you, right,
But you're using that one little detail, that one tiny
thing is some kind of like totem. It's this one
it's the signifier, this tiny flag flying above their head
that you have decided, for whatever reason, is good enough
(04:21):
evidence to open yourself up to this person and essentially
give them a fair shake that you might not give
to any other stranger. I've caught myself doing the same
thing too, even though I realized it makes no sense.
I mean, I think generally that you might be able
to make some kind of case that in some cases
(04:43):
shared aesthetics or shared values. Uh, you know that if
you like the same movie as somebody, it might embody
some kinds of values or intellectual predispositions that you would
find in common with other people who tend to like it.
But a lot of times that's not the case. I
don't know. I mean, I love Blade Runner, but there's
probably a lot of people who love Blade Runner who
(05:03):
are just absolute vampire. You saying they don't appreciate it
on the same level as you. Maybe that's it. I
wonder if you don't appreciate it on the same level
I do. I don't know. I've I've actually spoken about
this a little bit, but my thoughts on Blade Run
are mixed. But I do I do. I do love
Blade Runner. So today we're gonna be talking about a
(05:24):
hypothesis in genetics and genomics that is going to be
a kind of weird analogy to the personality tests that
we've just been discussing, and it's the concept of green
beard genes or the green beard effect. Now that the
sad news is that this episode does not really deal
(05:45):
with actual green beards. If you're looking for if you go,
if you're coming into this expecting an episode and a
weird genetic anomaly that makes people grow green beards, or
say a famous pirate with a green beard. Um, you're
gonna be disappointed on those counts. But the but the
underlying science we're going to discuss here in the genetics
is pretty amazing and pretty fascinating. Now I wanted to
(06:06):
come up with the backstory of the pirate green beard.
I couldn't think of what it is. What it's like
he's got algae in there or something. He just never
cleans his beard. Yeah, you're just um, I'm guessing you
probably have like really green teeth as well, you know,
and just maybe he eats a lot of plant matter
and it just kind of drolls down in his unwashed beard.
But you know, this does bring if there was if
(06:27):
there was a pirate with a green beard and he
met another pirate with a green beard, perhaps he would
have this effect. He would say, look, there is another
pirate who shares my esthetic qualities, perhaps my diet. Maybe
we have more thoughts on hygiene. Yeah. So the name
of the green beard hypothesis, which we will explain, comes
(06:47):
to us from Richard Dawkins, based on an example he
used to illustrate the concept in his nineteen seventy six
book The Selfish Gene. But the idea goes back to
the influential English biologists of the twentieth century W. D.
Hamilton's um And so the idea arises in the context
of a question about explaining how biology creates social behavior. Now,
(07:12):
this is one of the biggest, most difficult questions in biology, right,
So humans and other animals display these complex things like culture,
like aesthetic preferences, taste, uh, social behavior, all these things
that are complicated and have all these weird semi coded rules,
(07:34):
and we know at some level must be at least
semi dictated by genetic predispositions. But it's hard to know
what parts of culture and behavior are genetic and what
parts are just happenstances that you know that that arise
naturally and somewhat randomly. Well, we have all these levels
of cognition and culture that are kind of an illusion
(07:57):
and and and they're they're overriding the biology. But since
we are the illusion, it's hard to it's it's often
hard for us to really think about and in terms
of underlying biological properties. Yeah, so let's let's explore this
question that this problem with explaining social behavior through biology.
So we all know that species arise from the propagation
(08:17):
of self replicating molecules like DNA, the fundamental units of
heredity and DNA or genes. These are the parts of
your DNA that do something that are inherited from your parents.
And because genes make copies of themselves, we find some
of the same genes spread out across many different organisms
in the same gene pool. Now, obviously, genes that cause
(08:40):
an organism to die immediately at birth become less numerous
and eventually disappear. Genes that help an organism survive and
produce more offspring become more numerous in the gene pool.
These are the fundamentals of evolution by natural selection. This
is basic stuff. We we know it up to this point.
But here's a question. Why would an organism produced by
(09:01):
this process, that arises out of evolution by natural selection
ever displayed behaviors that we would call selfless or generous
or altruistic, for example, things like sharing food with another
organism or defending another organism in a fight. Now, I
do want to heavily qualify that by saying I think
(09:23):
It's probably not hard to explain why humans in particular altruistic, because,
after all, there appear to be a lot of ways
in which our complex brains can generate motivation for behaviors
that run contrary to our genetic fitness, and the simplest
example one of thousands would be celibacy. Whether for religious
reasons or philosophical reasons, or simply out of personal preference,
(09:47):
some people voluntarily choose never to have sexual relationships. This
runs absolutely counter to our genetic programming. Another more common
example would be the use of contraception. Many people who
are sexually active still choose to have no children, or
choose to have far fewer children than they technically could,
for a variety of reasons. So obviously there are some
(10:10):
ways in which the complex human brain has acquired the
capacity to override the genes that programmed it well, I think.
One one example that comes to mind is say, for instance,
my own son UH has adopted and so he is
not my biological offspring, but he he fulfills all the
needs and desires that that I had that I have
(10:30):
as a human for for offspring, for a son, right,
your genes don't care about him, but you do. Uh,
it's it's there in your brain, it is there in
your personality. So if you were only wondering about humans,
it might not be so hard to explain why we
would share scarce resources with a stranger, or risk our
own safety to intervene in somebody else's defense, or any
(10:53):
number of other selfless acts. We're smart enough to recognize,
maybe philosophical or religious reasons why we think we should
to help other people and override those selfish instincts to
act on those reasons. Or if you look at it
from another angle, maybe the more cynical person would say, well,
our complex, language obsessed brains are highly vulnerable to memes
(11:13):
that have the power to override the optimization of our
genetic fitness. Either way, human mentality appears to be fairly
unique on Earth, and it can account for behavior that
you wouldn't expect to find in other animals. But altruism
isn't only present in human beings with their religions and
moral philosophy and complex cognition. Altruism seems to be robustly
(11:36):
observed in other animals, from like complex mammals all the
way down to insects. Right, yeah, yeah, we have. We
have a few I think very illustrative examples here to
run through. Here's a crazy one. Vampire bats will regurgitate
blood for other bats who were unable to find a meal,
sacrificing their own immediate nutrition to keep another bat in
(11:58):
their community from starving. And this has been documented since
it was discovered in the nineteen eighties by a biologist
named Gerald Wilkinson. And that that's no small feat because
these bats are sort of operating constantly near the edge
of starvation. As we've talked about before. You know, if
a vampire bat goes a few days without food, it's
in a bad place. It can it can starve um.
(12:21):
And so sharing food like this is a significant sacrifice
for the good of another uh not necessarily related bat.
And you have to ask yourself, would your friends and
coworkers be selfless enough to vomit up blood in your
mouth if you've missed a meal. None of them have
ever offered, And it makes me feel rather sour. But
it's not even just the mammals, right, We see classic
(12:43):
altruistic behaviors in in uh animals that are thought of
as less complex. Right, Oh yeah, I mean bees are
a prime example of altruism, and I mean you social
insects in general have pretty much perfected altruism in many respects.
So worker bee works for the benefit of the queen's
offspring while for going reproduction herself. Genetically speaking, she is
(13:08):
not the genetic future the hive. The queen is, the
drones are, but the workers do all the work. In
a weird way, you can almost think about the insects
like this, being that the queen is the organism and
the worker bees are like fingers or appendages of the
major organism. Yeah, exactly, and it's just completely completely selfless
(13:28):
if you look at it from the right angle. Yeah,
but how about birds too, well, ravens who we've talked
about ravens a bit when we talked about bird intelligence. Uh,
Ravens have been observed to call in additional ravens when
they happen upon food, so like a mouse or something,
which doesn't make any sense that they have it, but
they have apparently have a special call that they use,
(13:51):
so they raise the alarm and say, hey, other ravens
that are not me or my children, come in here
and get part of this mouse. Why would you do that?
It doesn't seem to make sense. But some ravens even
return to their roost and recruit more eaters to come
and share in the feast. Yet again, so your friends
and co workers, they've never offered to vomit blood in
(14:12):
your mouth. They've also probably never offered to share a
dead mouse with you. Well, no, but on the rare,
on the on the instances where we've had catered dead mouse, Uh,
then it certainly people will come around and say, hey,
there's food on the question mark table, come and eat
with us. So, well, that's just their moral philosophy or
their religion or whatever. Alright, Well we have some some
(14:36):
other just quick examples throughout. Dolphins and elephants are fairly
complex social animals and display uh various forms of altruism.
They form social bonds, and then then they seem to
make conscious decisions to help members of their group. Yeah,
and so we have all these examples of these are
by far not the only examples. There are just tons
of documented examples of animals in the wild or in
(15:00):
a conditions seeming to help other animals who are not
their direct offspring at their own at their own expense.
And obviously we can see why evolution would select for
genes that cause organisms to be altruistic towards their own children. Right,
that's kind of the whole point. Your genes optimize your
body to have lots of children that can carry as
many copies of those genes into the future as possible.
(15:23):
But why would evolution produce creatures that sacrifice some of
their own safety or resources to help save another creature
that wasn't their direct offspring? I mean, wouldn't wouldn't genes
that promoted selfishness and cowardice produce the most grandchildren on average? Well?
I mean one obvious answer here is that there's an
(15:43):
individual survival advantage in groups, right, Right, The group kind
of becomes the meta organism, and natural selection encourages the
pro group members of the metal organism and not and
not the lone wolves. Now, this is attempting direction to
go in, but there are critic of this type of thinking,
So lots of scientists have tried to go in this direction,
including EO. Wilson in later years. Uh. And this is
(16:06):
sort of related to the concept known as group selection. Right.
The idea that natural selection can select for not just
the survival of individual genes or the survival of individual organisms,
but groups of organisms together. This is also known as
multi level selection. But, like I mentioned, this idea has
a lot of harsh critics, including Dawkins. I mean, he's
(16:29):
criticized this idea. And here's one potential snag. It's true
that teamwork pays off, right, But you know what pays
off even more than teamwork? Letting other people do the
team Ah. This is the This is the classic um
A classroom situation where you've been assigned to groups and
you're gonna have somebody in the group who's a real
(16:50):
hard work, are very dedicated. You have some other individuals,
and you can have at least one person who's just
gonna coast right right, Yeah, So you let the rest
of the team do the work while you sand bag
and reap the rewards. So if you imagine if you've
got wild dogs that have a gene that causes cooperative
pack hunting behavior where every dog chips in and does
their share of work in the hunt, and in turn,
(17:12):
this increases the group's chances of catching prey and then
they all share the benefits. That would be great. Everything's
going great if you've got dogs with those genes, But
then one of the dogs in the pack acquires a
mutation that says, actually, don't help with the hunt, just
hang around until your pack mates catch something, and then
show up and plunge your face into that delicious viscera.
(17:35):
A dog with this trait would spend less energy hunting,
and it would risk less injury, and it would still
get the rewards of the hunt, so it would ultimately
benefit more than any of the team players, and on
average that that freeloader dog would have more offspring, meaning
that over time the freeloader gene would become more common
than the team player gene, and the pack hunting system
(17:58):
would sort of fall apart. So systems that rely on
benefits of group cooperation for the sake of the group
as a whole are sort of pervasively undermined by the
interests of individual organisms and individual genes within the group,
which will sort of inevitably find ways to run counter
to the success of the group as a whole. So
(18:20):
to sum up, we can show that in general, natural
selection will tend to push organisms to favor their own
success at the expense of others and at the expense
of their groups. And yet at the same time, group
cooperation and selflessness is present in nature, so there must
be some way to reconcile these observations, right, yes, and
I imagine this is where the green beard comes in. Well,
(18:42):
the green beard is going to be one weird way
of branching off of this question. Actually, the main answers
to this question are not going to be the focus
of today's episode, but we should mention them. So two
of the main answers that emerged in the twentieth century
to answer this question, or what's known as kin selection
and what's known as reciprocal altruism. So reciprocal altruism is
(19:03):
basically another way of summing it up, is just the
phrase tip for tat. And while in many cases it
can be hard to verify outside of lab conditions, you
can sort of build models of organisms that behave on
this principle and it does appear to be stable if
and the way this works is like this, So if
a member of the pack is mean to you, or
(19:23):
if they try to cheat and be selfish, you repay
them back the same way you're mean to them back
you you don't share with them. But if another member
of the pack is nice to you, you're nice back.
So essentially you just mirror. You start with the basis
of being nice, and then you mirror the you mirror
the behavior that people display towards you. Okay, well that
(19:45):
that makes sense. I think everybody can fall fall behind that. Yeah.
And if you run models like this, it is mathematically stable.
Genes that encourage this type of behavior don't tend to
get eliminated from the gene pool, but they can reach
a kind of stable equilibrium. But the other main idea
is what's known as kin selection, and this was explored
in the nineteen sixties by the English biologist we mentioned earlier, W. D. Hamilton's.
(20:09):
Now Hamilton's used these quantitative genetics modeling methods, which is
like math about how genes are inherited and distributed to
show something interesting, It makes mathematical sense for genes to
optimize for altruism toward blood relatives other than our own offspring.
So it turns out that for a sexually reproducing species
(20:31):
like us, you share the same percent of your genes
with each of your children that you do with your
full brothers and sisters and with your parents. In each case,
you share fifty percent of your genes with them, and
to a lesser extent, the same goes for other members
of your family. Further removed, you'll share more genes with
your aunts and uncles and nieces and nephews than you
(20:52):
do with the general population and so forth. And given
this calculus, you can work out how genes that direct
organisms to be generous and altruistic toward family members become
more numerous in the gene pool than genes that direct
organisms to be exclusively selfish and unhelpful to anybody. So
if I have a cousin that appears on America's Got Talent,
(21:15):
I'm going to root for them in part because they
share more of my genes than anybody else that's contestant
on that show. I mean, on average, they probably do.
You might have like a secret unknown brother or sister,
but yeah, yeah, on average, that's going to be the case. Now.
And of course, there are lots of weird ways that
maybe things like kin selection or reciprocal altruism uh could
(21:39):
be could be sort of modified in various circumstances to
generate the mechanisms that create altruism that get applied in
other ways. But it is in the context of discussing
this this whole question about altruism and biology in the
Selfish Gene that Dawkins also came up with this weird
hypothetical idea for one weird type of selective altruism, the
(22:03):
green Beard. All Right, we're gonna take a quick break
and when we come back we will join back up
with Captain green Beard and discuss the details of of
of this idea. Alright, we're back. So we were mentioning
how the name of the green Beard gene comes from
(22:24):
an example given by Richard Dawkins in The Selfish Gene
in n So, Dawkins is pointing out how any arbitrary
gene will become more numerous if it makes carriers of
that gene friendly and helpful toward other carriers, right, and
that sort of makes sense. It says like, if you've
got gene A in your body, gene A does especially
(22:45):
well if it makes your body give food and night,
you know, nice behavior toward other carriers of gene A. Right,
it's just a boost for gene A across the board.
So he starts talking about the example of the gene
for albinism, which is a genetic condition that causes the
carrier to have unusually low levels of the pigment melanin,
(23:06):
leading to paleness of skin, hair, and eyes. And hypothetically,
a really successful version of this gene for albino traits
would not only produce the visible traits, but it would
motivate a carrier to be helpful toward other people who
have these visible traits. Now keep in mind, this is
not how the albino traits work in in reality. This
(23:29):
is just a hypothetical alternate version of them um And
if this were to exist that way, everyone who has
this particular gene would have more offspring and the gene
would become even more abundant. But would we find something
like that in nature? That's the question, and Dawkins writes
the following quote. It is theoretically possible that a gene
(23:49):
could arise which conferred an externally visible label, say a
pale skin or a green beard, or anything conspicuous, and
also attendance to be specially nice to bearers of that
conspicuous label. It is possible, but not particularly likely. Green
beardedness is just as likely to be linked to a
(24:10):
tendency to develop ingrown toenails or any other trait, and
a fondness for green beards is just as likely to
go together with an inability to smell frieze is it
is not very probable that one and the same gene
would produce both the right label and the right sort
of altruism. Nevertheless, what may be called the green beard
altruism effect is a theoretical possibility. So this is where
(24:35):
the green beard idea comes from. And to be clear,
Dawkins is not saying that he expected to find anything
like this in nature, right, I mean, it would be
it would be a tough sell to say that there's
just one gene or one tightly linked group of genes
and that does all that work. It's got to produce
the externally detectable trait. It's got to detect that trait
(24:56):
in other people, and it's got to make you a special,
really nice or in some way manage a positive interaction
with other people who have that externally detectable trade. And
uh so, so he wasn't saying you'd expect to find it,
just that it was an interesting hypothetical possibility, Like he's saying,
it's possible that the murder was committed in the library
(25:18):
with the candlestick by Colonel Mustard with a green beard
by Colonel ver dear Beard. But but it's just a
hypothetical situation, Yeah, and one thing one that would be
difficult to come about. But if it did exist, it
would be encouraged by natural selection. Right, he's sort of
pointing out how natural selection would favor this. You just
wouldn't expect it to arise in the first place. But
(25:41):
nature is stranger than our imagination. Ah, and this is
where we get into actual examples in nature, the green beard.
So this was not what we originally expected, right, I mean,
geneticist didn't think that you you discover things like this
in nature. But man, the actual world is always surprising us.
(26:03):
So let's meet a species. Solenopsis invicta. It sounds pretty serious,
it sounds pretty pretty indomitable. It's like the it's like
the you know, the Roman Emperor species, And it kind
of is because that is the name of the red
imported fire ant, which is native South America. It has
spread everywhere from Australia to Asia, the United States. It's
(26:26):
all over the place now, and woe to us for
that fact. They were first introduced to the United States
sometime in the nineteen thirties or forties, and now they
are known as an invasive pest with hot needle venom
and a ferocious fighting response when their nests are disturbed.
In fact, in our episode about the biophelia hypothesis, we
talked about that great video of EO. Wilson trudging through
(26:48):
the woods until he finds a red fire ant nest
and shoving his hand into it so he can show
you how much it hurts. Oh, yes, this is this
wonderful footage. I love that he just he stirs them
up less and krawling hand lets them sting him in
almost like a religious moment. For Yeah, he's so happy
about it. If only people in general could find something
that they love as much as this man loves these
(27:10):
ants that are furiously pumping their venom into his body. Anyway,
another perhaps interesting thing about these fire ants they exist
in two sub populations. So they've got so they've got
this species, and then two subpopulations have very distinct ways
of making a living. One tolerates only one queen per
colony and the other has multiple queens per colony. Uh,
(27:34):
and those are known as the mono guy in versus
the polygone types. You know, one one queen multiple queens.
So in Lauren Keller and Kenneth g Ross published an
interesting report in Nature about Solenopsis invicta, and Keller and
Ross were studying red fire ants of the polygone variety,
that's the kind that has multiple queens. So within the
(27:57):
genome of these polyguine sol Anopsis invicta, there is a
gene locust called g P nine and a couple of
terms to explain real quick. In genetics, a locus is
just the location on a chromosome where you know you
can look to find something, where you know you can
look to find a gene or one of its alleles.
And allele's are variable forms of a gene appearing at
(28:21):
the same locus. So, for a simple example, at the
locusts q x one, you might contain a gene that
regulates the speed at which your toneails grow. And if
you have one allele at q x one, your toneails
grow fast, and if you've got a different allele at
q x one, your tone nails grow slow. Now back
to the fire ants. They've got this gene locust called
(28:42):
g P nine with two allele's big B and little B.
And because they have two sets of chromosomes. The ants
can have three different types of arrangements at g P nine.
They can have big B, big B, Big B little
B or little by little by. All right, now, if
you were to watch these colonies up close, where a
(29:03):
new queen reaches sexual maturity and starts trying to mate
and lay eggs, you notice something weird. Only the queens
with the two different alleles, the big B little be
jeans at g P nine live long enough to reproduce.
Why is that what happens to the others. So first,
it appears that queens with little be little bee die
(29:24):
very young of natural complications. This just appears to be
a lethal recessive combination. And we see this a lot
of times in nature where if you've got two copies
of this recessive gene, it's it's bad news for you
and it can lead to a genetic condition that kills you.
But what happens to the big B big B queens. Well,
Keller and Ross found out they get violently executed by
(29:47):
their own workers. The ants of the colony tear their
soul apart. So furthermore, they discovered that it was primarily
workers bearing the little bee allele that did the any
work of killing the queens without it. So if you've
got a queen that's big B big B, the workers
that have a little bee allele will surround it, bite
(30:10):
it and kill it because it is it's essentially in
some respects, it's like a foreign queen. It does not
share the same allegals as it does. Yeah, that's what
appears to be going on. But how how does that happen?
I mean, normally you wouldn't be able to look at
somebody and say you're missing one particular gene that I
(30:32):
have and I'm going to kill you. So what's going on?
So the worker ants with that little bijeene at g
P nine tend to violently massacre any potential queens that
don't carry the little bee gene at g P nine.
Uh So it sounds like we might have a slightly
modified version of the green beer gene on our hands.
But here's a question. How how do those workers know
(30:55):
when the new queen has the right a leal or not?
Here's a clue. The author's noticed that sometimes after a
worker ant took part in a mob executing a big
B big B queen, the worker aunt would then be
attacked by other ants in the colony. So you take
part in the mob, you kill that big Bi big
(31:15):
b queen, then you walk away. Then other worker ants
kill you and you know it. And there's no politics
in the insect world, so you know, it's not just
some sort of a situation where the assassin has to
absorb the blame for the regicide, right right, right, It's
not like the king slayer is now being you know,
talking to me, like, so what was going on? You
(31:36):
have to wonder was something rubbing off on the killer
worker And this led the authors to suspect the culprit
is pheromone based. So they tested this by rubbing worker
ants against two different types of queens, the big b
big be queens and the big Bee little bee queens,
and then releasing those workers to their colleagues, and sure enough,
(31:57):
the the other workers tended to a hack the ants
that have been rubbed against the doom big Bi big
Bee queens, but not against the queens with a copy
of the little be allele. So to know that we're
looking at an actual green beer gene, we've got to
remember the gene should be doing three things. It's got
to produce an externally detectable trade. It's got to detect
(32:18):
that trade and other individuals, and it's got to provide
preferential treatment to individuals bearing that trade. So it looks
like maybe maybe what's going on here is this ants
with the little bee gene at g P nine will
attack and kill anything that smells like a sexually mature
queen unless it also carries the chemical signature generated by
(32:41):
the little bee gene, which switches off that kill drive
in the workers. Interesting. Okay, so this looks like, if
these findings are correct, a genuine green beer gene found
in nature, there's this one gene or some incredibly tightly
linked group of genes going off the g P nine locusts.
(33:02):
That says, if the queen doesn't have this one gene
killer al Right, well, we're gonna take a quick break
and when we come back, we have some more possible
examples of the green beard gene going on, and we
will talk about the wood mouse and the sperm train.
(33:23):
All right, we're back. So, Robert, you promised before we
left that you were going to tell me about sperm trains. Yes,
Uh so I'm gonna gonna go ahead and back up
here a little bit for everybody before we get into
just you know, full on with the sperm train. If
you were like us, then you've probably read and viewed
a great deal of science content about sperm over the years. Uh.
(33:45):
This is a topic that pops up in nature documentaries,
science news articles, and seemingly endless academic papers. Well, the
sperm it kind of creates a microcosm of the whole
natural world, right, Yeah, it is because you know, it's
a situation where when when the sperm are competing against
each other to go after the goal that's happening on
the inside. On the outside, of course, we have all
(34:06):
these various uh mating competition scenarios that factor into our
nature documentaries, you know, where different males are competing uh
to mate with the female, or multiple males mating with
the female, what have you. Uh. So it's interestingly we
have kind of this outer war of mating war going on,
and then there is an intermating war as well. Because
(34:28):
we have all these examples of of sperm uh playing
a role in this outer war. We we learned, um,
you know, the violent details of copulation and how sometimes
they can deter females from acquiring additional males um. There's
also the interesting hypothesis regarding Kama kaze uh spermatozoa in
rats and humans, with the hypothetical primary function in these
(34:52):
particular sperm of incapacitating sperm of arrival male. It's kind
of like dog fighting sperm or It also makes me
think of say a miniature Star Wars space battle taking
place inside and that the egg is quite ironically the
death star maybe the life star. Well yeah, if you're
a sperm, you don't want to blow up the egg.
(35:13):
You want to join in harmony with the egg. Well yeah,
but but but you have that one individual sperm wants
to do it, and it's it's it's a race. It's
a competition life star like that. Yeah, now you kind
of grow used to this trend, right, there's competition, ruthless aggression.
Sperm is the life seeking missiles at war with their rivals.
Multiple matings resultant sperm competition and even mixed paternity. But
(35:36):
sperm are also competing against all of their their brethren. Uh.
And therefore it's a bit shocking when you realize that
there are cases of sperm cooperation. So most examples of
this occurs in the let's face it, freaky world of mosques,
as well as the the aforementioned politics free realm of insects.
(35:56):
But there's actually an example in the mammal realm as well,
as demonstrated in the two thousand two paper. And I
love this title, exceptional sperm cooperation in the wood mouse
exceptional A plus sperm cooperation. So the wood mouse this
is a you know, a Western European rodent. It's small,
but it has tremendous sperm output. The mice in general,
(36:20):
uh that they have rather large test these tests or
five percent of their body. And if we were if
this were the case with humans, to put that in perspective,
a male human would have seven points points seven pounds
or three point five ms of tests. So these uh,
the fact that they're over sexed, it would seem this
(36:41):
is helpful because they engage in quote scramble competition, uh
to mate polygamously with promiscuous females. As such, you would
expect a lot of sperm competition going on there. Race
to the life star. And this is where the train
comes in because the wood mouth sperm feature quote extremely
(37:03):
long apical hooks and they use these hooks to form
together into a store to sort of think of it
as a sperm vultron, or, as the paper puts it,
motile trains of spermatozoa comprising hundreds to several thousands of cells.
These trains these sort of you know hooked together, you know,
(37:25):
wheels of sperm. Uh. These trains allow the bound sperm
to travel at greater speeds up to fifty faster than
loan sperm out there going on their own. But as
they do that, they've got to be given a leg
up to these other sperm that they're in competition with.
That's the thing, because ultimately only one sperm can get
(37:46):
in there. But they're they're all working together. It's it
makes me think of these scenarios where a bunch of
villains team up, uh, and then they're all going to
turn in turn on each other at the end, but
for a little while they're working together, like a sinister
six situation. Right. I thought you were going to say
suicide squad. Well, I guess that's a similar example. They're
all villains, right, are they so untold? I I didn't
(38:08):
see it. I I tried to check it out on HBO,
uh to see what everyone was talking about and made
it made it just about like five minutes in. But
maybe it's a great film. I could be wrong. So
in these cases, the hook up occurs one to two
minutes after ejaculation, and that's when head to head or
tail tail to head hookups occur. So they have hooks
(38:29):
on their heads as well in this scenario. But again,
only one sperm may enter the life star. It's it's
it's like the scene with the you know, trying to
shoot the bolts into the death Star. Uh. So the
train starts to decouple about twenty to thirty minutes after forming,
and in doing this, many of the individual sperms seemed
to sacrifice themselves and uh and some might be even
(38:51):
marked for death ahead of time, or there might be
competition there at the end. So again, think of a
group of supervillains. They've they've worked together so far, but
after they kill the Batman or the Superman, they're just
gonna turn on each other. So how do the researchers
connect this to the idea of the green beer gene. Well,
this is what they say. Quote a green beer gene
might evoke such cellular cooperation, although other genetic mechanisms cannot
(39:17):
be excluded at this stage. A green beard is a
gene that recognizes copies of itself and other individuals and
directs benefits to those individuals. So the idea, here's the
green beer gene would be the deciding and factor with
which sperm you're going to team up with in this battle,
because you certainly are not gonna gonna want to hook
up with sperm from other uh individual mice that have
(39:41):
made it with this particular female. Right. Interesting, So so
they're saying this could be one explanation of the behavior
they're seeing here. Yeah, this is Life Race two thousand.
All the cars are heading out, but some of these
cars are realizing that they can work together and form
a train uh to to to out maneuver and and
uh and and outperform their competitors because some of the
(40:04):
cars have exact copies of the driver in each one. Yeah,
like multiple Frankenstein's that was a deep cut. I scared
somebody off there. Roger Corman's Death Rays two thousand, if
you want to want to get all of that, Okay,
So that's another So there really does appear to be
a green beer, you know, if the observations are correct,
there really does appear to be a green beer gene
(40:25):
working in the fire ants. Uh. It looks like green
beer jeans are a good candidate to explain what's going
on here in the sperm trains, but it's not a
sure thing. Other mechanisms might explain it. In two thousand
and eight, I should just mention quickly there was one
paper that seemed to identify a green beer gene that
was driving cooperation in yeast cells, and that that gene
(40:49):
was called f l O one. But just recently I
was reading about how there is apparently green beer gene
activity in slime molds. Our old friends. Oh yes, yeah, yeah,
this was pretty interesting. So to refresh slime molds, which
which I like to compare to science itself at times.
I think it's a good metaphor for it. Slime molds
(41:12):
are microbes that live as single celled organisms, but they
kind of vultron together into a great communal metal organism
that quests after food. It's a two vulturo on episode. Yeah. Uh,
and you know, there's some fabulous experiments that show the
sort of communal intelligence that it has, like a very
non non non human form of intelligence. So it's problem
(41:34):
solving ability. Yeah. Well, in March of this year, geneticists
from the Universities of Manchester and Bath discovered that these
individual cells are capable of choosing who they joined forces with.
So it's not just you know, every um slime mold
individual is gonna come together like they're gonna be a
(41:55):
little bit choosy and uh. And it seems that green
beer jeans factor into it. Oh okay, So you're a
slime mold cell and you've got this one gene that says,
if there's another slime slime mold cell that has this
same gene, join with them and conquer the maze. Okay, yeah,
it's so it's pretty straightforward in that regard that the
(42:17):
gene in question encodes a molecule on the surface of
a slime mold cell and it can bind to the
same molecule of another slime mold cell. Now, most my
slime molds strains have a unique version of the gene. Okay. Now,
there's a great deal of diversity in slime mold green
beer genes, according to the study, but individuals show a
(42:38):
preference for cells with like or similar green beer genes,
and the assembled whole the resulting you know, larger mental
organism slime mold. Um, it actually performs better. It does
better if it's formed of preferred partners as opposed to
you know, non preferred partners. As such, these beer genes
(43:00):
listening to govern in a particular specific cooperative behavior in
the slime molds. So the way it works is it
just makes you sticky for other slime mold cells that
have this same gene. Yeah, basically like on a very
it's it's kind of just like the real pro gloves. Yeah,
it's like the simplified version of why liking the same
(43:21):
band um binds you to somebody else. So to summarize
going off the paper here, Uh, the green beer genes
achieved the following in the slime mold. So they predict
partners specific patterns of cooperation by underlying variation in partner
specific protein protein binding strength and recognition specificity. Uh. They
(43:45):
also increase fitness because they help avoid potential costs of
cooperating with incompatible partners. And also they generate a homophilic
binding spectrum that allows individuals to identify appropriate partners with
whom to engage in cooperation. And its states that it
also serves to stabilize cooperation in the face of selective
(44:08):
pressure for the emergence of quote false bearded cheaters who
by providing information that can be used to differentiate compatible
from incompatible partners. So this is a new ripple. This
is a new ripple. So we started with this hypothetical
idea that Hamilton and Dawkins talked about, saying that it's
(44:28):
not necessarily going to be found in nature. It's just
one hypothetical thing that could work if it ever were
to arise. Now we're finding examples of it in nature.
The green beard gene, the gene that says, hey, I
see you have this gene too. I like you. I'm
going to treat you right. But now we see that
there are false beard pretenders. You could have a gene
(44:48):
that in fact signals the same thing as having the gene,
or something that could easily trick you into thinking they
have the gene but they don't have it. Well, you know,
I'm reminded of the slime mold moving through the maize
that you know, our scientific uh quest to understand the universe.
So anytime we find something new, there's always some new ripple,
some new complication, uh. And and and some new level
(45:11):
of the complexity of life. So what is the what
is the liking the same band equivalent of the false
spirited cheaters? Somebody who you think signals liking the same band,
but in fact they do not really like them. Is
that the the fake tool fans you were talking about
at the beginning, maybe, or maybe a better example would be,
(45:34):
like there might be a band that was really popular
and you dig them, somebody else doesn't. Really they're not
They're not a true fan. They just they're maybe a
little nostalgic for it. Or they remember listening to this
band in high school. But where have they been, you know,
the subsequent decades. So they've got the bumper sticker on
the back of their car. But if you started talking
(45:56):
to them, you would find that the compatibility you were
seeking is not really. It's all superficial, right, or maybe
it's Uh. It also reminds me I think it was
Kids in the Hall skit where somebody's trying to buy
a copy of The Door's Greatest Hits at the CD
store and this guy comes in Elections and was like, no,
you have to start with the first album, and then
you have to listen to it, like there's very specific
(46:18):
instructions about where you listen to it, how long you
listen to it, and then only then can you move
on to the second album, and you have to go
in order. So he's instructing him how to be a
true long term fan and not like a cheap skip
to the greatest hits fan. How to be a true
pretentious jerk. Do pretentious jerks glom onto each other in
the same way that Greenbeard slime mold cells do? I
(46:39):
don't know, or maybe I mean I guess they do.
But you could also argue that they don't have the
binding factor. They're just too pretentious about their their stuff.
They can't actually enjoy it with other people because they
have to be the they have to be the biggest
fan in the room. They have to be the smartest
fan in the room. But we're getting into the human
complexities here of of of sharing and things. I think
(46:59):
we've run more fild with our metaphors and we've gone
off the deep end. Anyway, picking up from our intro
to this episode, where we had to lay the context
about the discussion about altruism and biology and the idea
about the different levels of selection I've been thinking that
this would be daunting because it makes biologists uh ruffle
(47:20):
their feathers and get very upset. I think maybe in
the future we should try to do a big episode
or maybe a two partter on the levels of selection
debate in biology, like this big controversy over whether group
selection is a real thing or not, or whether whether
there's also arguments about the arguments, like whether the argument
(47:42):
is real or whether it's just semantic um and so
I think I think there's a lot of interesting stuff there,
but I know it's a big, thorny, controversial issue that
has a lot of uh petty sub issues. Well, no,
that could be fun. I mean, who knows. Maybe it's
a topic that it would be Uh it would be
sensible to bring in a guest to help us and
(48:05):
navigate all the controversies. Well, maybe we need to bring
to two guests, one that take each side. Ah, and
then we turned into a debate show, but we're not
we're not going to do that. Well anyway, if that's
something you would like to hear, maybe you should let
us know. Yeah, yeah, for sure. Hey, before we close
out here, Uh, this is one of the first episodes
(48:26):
that we're recording after the total solar eclipse here in
North America. Uh And, as previously stated, you went up
to Tennessee to to check it out, to be within
the line of totality, and and I went up to
Blue Ridge, Georgia in the North Georgia Mountains and observed
it as well. So what are your thoughts? It was?
(48:49):
It was amazing. I was trying to uh convince everyone
that we should go up to the path of totality,
and they were like, but hey, isn't it like totality
here in Atlanta. And I was trying to explain the
difference between like ninety nine point nine and is is
apparently huge. And I'm glad we went. I'm glad we
(49:10):
did it. It's I don't want to sound flip when
I say this, but it was a religious experience. I mean,
it was a really truly astonishing thing. I've never seen
anything like it before. It was amazing watching all the
different physical changes going on around us. As the totality approached.
There was this moment where it was probably about as
(49:30):
the sun was about seventy covered, maybe a little bit more,
that I started to notice that there was still still
the appearance of sunlight all around me. So it was
like a bright summer day, but suddenly there was I
didn't feel the heat anymore. The sunlight felt cool, and
I could stand in the direct sun and my skin
didn't have that that radiation reaction it normally does when
(49:51):
you're standing out in the direct sunlight. There. I don't
know that. The colors became so strange as it came on,
and then once the totality hit it was true what
I read in advance that said, you know, it can
feel like it's over in seconds. It totally did. I
was just standing there gaping at it, and then I
after almost no time at all, it was over. Yeah.
(50:13):
I was really impressed by it as well. I mean,
aside from just the the the actual spectacle of the
full eclipse, just seeing the ring there in the sky. Uh,
you know, all the subtle stuff was very in a
way unnerving, and and and and he felt like you
were kind of crossing over into, uh, you know, an
(50:33):
abnormal realm because that you had this sense that it
was it was dusk, but there was no sunset on
the horizon, you know, there was this uh this also,
I certainly observed the changes in the animals because I
was in the forest in the mountains, So the cicadas
all died down, and it suddenly the cicadas stopped making
(50:55):
their noises and the crickets started up. Yeah, I observed
that too. Up in Tennessee. We heard the nighttime insects
begin to whir to life. Another thing when we saw
moths as well, Like suddenly there were moths flying around.
So I got to see because I knew in advance
to look to the west, like we talked about in
our eclipse episode, there were some clouds in the sky
(51:19):
to the west of where we were, and I kept
my eyes focused to the west right as the last
of the Bailey's beads were fading, and as it was
coming on, and I saw the shadow pass over the
clouds to the west of us, and it was so
cool to see like that, we had white clouds and
then suddenly black straight over them. And of course everyone
experienced the drop in temperature, but we also witnessed what
(51:41):
I believe was, you know, weather changes because of that,
because the it was a little bit cloudy, and the
clouds were on the just teasing with us with the
possibility of obscuring the total eclipse, but it held off.
But then right after the eclipse occurred and was and
and and the moon was big getting to move out
of the way of getting away again. Uh, there was
(52:03):
this um suddenly a lot of cloud cover moved in
and then it almost immediately started raining. Yeah. I think
we had some strange weather the rest of the day.
How about your dog, Charlie? Was he there? No, we
left him at home. I we thought about bringing him,
but the place we were going was it was a
college campus up in up In, Tennessee, and we didn't
(52:25):
know how many people would be there, and we didn't
want him to get upset if there was a big crowd. Um,
so we we just left him at home and he
was fine. Well, Uh, my son came. He really enjoyed it.
It was just a great experience. So uh, And I
know I reached out on the Facebook on social media.
A number of our followers there, our listeners there, they
(52:46):
chimed in those that either experienced the partial or the
total eclipse. And certainly we'd love to hear from anybody
else who has particular observations about how the environment reacted
or or how you reacted to the total eclipse. Uh,
you know, we would love to hear your experience as well.
One last thought, photos don't do it justice. Yeah, absolutely not.
(53:09):
I mean I've seen tons of photos of past solar eclipses,
but it's not like seeing it in person for yourself.
So if you ever get a chance in the future,
if you want to, you know, if you're in South America,
or you want to fly to where one of those
total eclipses in upcoming years is coming, or if you're
in the United States and you just want to go
ahead and start planning for it's really worth it. It's
(53:31):
something unlike anything else you'll see in your life. All right, Hey,
In the meantime, waiting for the as you wait for
the next episode of Stuff to Blow your Mind to
come out, head on over to Stuff to Blow your
Mind dot com. That's where you'll find all the podcast episodes,
including our episode on the on the the the solar
eclipse then that came out in the last week or two.
(53:52):
Be sure to check that out. Also, you'll find links
out to all our various social media accounts such as Instagram, Twitter, Um, Tumbler,
and Facebook. Hey, and on Facebook, we have a group
now the discussion module. Be sure to check that out
because that's a great place to have more long form
form discussions with other listeners and UH and sometimes the
hosts as well. And you can also just bring up
(54:15):
like cool ideas, cool articles, et cetera, and there'll be
some some other like minded individuals to bounce that off of.
And hey, if you want to get in touch with
us directly, as always the old fashioned way, you can
email us at blow the Mind at how stuff works
dot com for more on this and thousands of other topics.
(54:44):
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