February 27, 2025 • 30 mins
Tom unpacks the complex definitions of life and challenges common misconceptions about living organisms, from mules and parasites to viruses. Listeners gain insights into the key characteristics that define life while exploring philosophical questions surrounding it.
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Tom (00:01):
Hello out there and welcome to another episode of Tom's
SciCast.
I'm your host, Tom Kennedy.
I know I've been gone a while,I've been busy and in fact next
week I'm actually leaving to goto Costa Rica with my buddy to
go find some sleeping lizardsand collect more data on them.
Well, since I've been gone,I've been doing a lot of work
actually.
I know I'm really diving intosome astrobiology and then I'm
(00:27):
hopefully going to publish somepapers on astrobiology.
Very excited about that and,yes, I will podcast that.
But as I've been doing someresearch and listening to lots
of other podcasts and readingbooks and reading up on the
whole field, I've realized thatthere's been a few
misconceptions out there and Igot to do something about this.
(00:49):
Right, I want to see if I candispel some of these
misconceptions, and the firstpaper I hope to publish on some
of these in March is actually atheory of life which I'm not
going to publish it quite yet asa podcast.
I'll wait till I actuallysubmit the paper.
But let's kind of jump intosome of these misconceptions and
(01:10):
of course, one of these has todo with what are living
organisms exactly, or what islife.
So my paper is going to be on,so I'm not going to jump into
all of it here.
But there's lots of definitionsout there on life.
If you took an intro to biologyyou may have gotten five
descriptive things about life,something about metabolism,
(01:32):
reproduction, evolution usingenergy.
If you took an AMP class, theirtextbook mentioned something
about moving and of coursethere's response to the
environment.
And if you're NASA, you call ita self-sustaining chemical
reaction capable of Darwinianevolution.
I kind of like that one, butthere's more to that.
(01:54):
But these definitions on somelevel are all problematic.
I mean, let's just take NASA'sdefinition, which I think is
actually pretty good as a simpledefinition.
It says a self-sustainingchemical reaction.
All right, I'm not exactly surewhat they mean by
self-sustaining.
I imagine it's somehowautocatalytic and can read the
(02:18):
environment right To take innutrients and information or
take in nutrients and energyfrom the environment and keep
going over time.
And if that's your system, well, it can't be an organism,
because organisms don't evolve.
An organism cannot evolvebecause we define evolution as a
change in allele frequencies.
(02:38):
It's the change in your DNA.
So a population that's thesmallest unit of evolution DNA.
So a population that's thesmallest unit of evolution.
So even NASA's definition theorganisms can't evolve.
So what is your system?
That is self-sustaining, thatis continually evolving through
natural selection.
I just thought I'd throw thatout there to get us warmed up
(02:59):
here Now listening to a fewpodcasts on astrobiology.
Of course, astrobiology ispre-paradigmatic, right, which
means there's not a reallyunderlying or overarching theme
or set of theories to unify thefield.
You go to physics you've gotrelativity, you've got Maxwell's
(03:19):
equations, you've got gravity,you've got relativity, you've
got quantum mechanics, but youhave these bases to unify the
field.
Biology has evolution bynatural selection, but
astrobiology is a little bitpreparative at it because we're
still trying to figure out whatlife is.
So all right.
(03:40):
So if something's live, ifthere's life, so what does life
do?
And of course I've alreadymentioned these things.
You know most people think thatlife reproduces, it evolves
over time.
There's some metabolism goingon, there's some
self-organization going on.
So invariably on these podcastslisten to some pretty
(04:00):
entertaining astrobiologists.
They would invariably ask aquestion like is a mule life?
Because a mule is sterile, itcannot reproduce.
Well, wait a second.
How about a person?
If they don't reproduce, arethey not life?
Of course mules are life,they're alive.
They're just a dead end of thatinformation driving that system
(04:22):
right.
There's still life.
They just can't reproduce.
The way I like to think of thisis a living organism is the
physical embodiment of life,right?
So life is a phenomenon, it's aprocess, it's doing these
things, a mule that's sterile,it's alive and it is part of
life.
(04:44):
Here's another misconceptionwhere somebody who hasn't
studied biology their whole lifemay make a simple mistake and
that's okay.
I mean, biology is complicatedand I'll tell you what I don't
get all of quantum physicseither, or relativity.
That stuff's pretty tough, it'svery mathematically driven and
I'm not that mathematicallyinclined I only went up through
(05:07):
differential equations incollege and so some of that
stuff escapes me.
But physicists often come tobiology and well, they don't get
some of the nuances justbecause biology really takes a
long time to understand it at abroad level.
And one of the interestingthings I've heard an
(05:28):
astrobiologist muse orcontemplate or throw out there
is they asked if parasites arealive.
And the reason why they askedif a parasite is alive is
because they made theobservation that many parasites
depend solely on a single host.
All right.
So the idea for these guys waslike well, maybe they're not
(05:51):
alive because they're like avirus.
A virus depends on a bacteriaor another cell.
Viruses depend on life.
I'll come back to that one in asecond because I know you guys
are ready to hear about theviruses.
But let me dispatch this thingreally quick about parasites.
Parasites are organisms.
They are made of cells.
Some parasites are as small asbacteria.
(06:13):
Some are eukaryotic cells, likePlasmodium falciparum that
causes malaria.
That's an intracellularparasite.
Malaria that's an intracellularparasite.
There are parasites that includemany, many types of worms,
tapeworms and liverworms and allthe flukes and trematodes and
nematodes so many differenttypes of parasitic worms.
(06:36):
They are organisms, they arecellular, they have cell
metabolism, they extractnutrients from their environment
and they reproduce, and some ofthem produce millions of eggs
over years.
And some of them are so highlyevolved like a tapeworm.
They don't have a mouth, theydon't need a mouth.
They're flat Hence flatworm andthey look like tape Hence
(06:59):
tapeworm and they absorb all thenutrients in your gut right
across their cuticle, rightacross their skin, right so they
don't even need a mouth.
They are just incrediblyspecialized animals or bacteria
or cells Right, so they'reincredibly specialized to live
in a very specific environmentwith very specific requirements.
(07:27):
Like some parasites can onlyattack one particular type of
host.
That's how specific some ofthese can get.
So they're totally alive, right, they're living, they're
metabolizing, they're they'rereproducing.
They're just highly derived,okay, okay now, um, I'll go
ahead and let's get to thisviruses.
There's a virus alive.
(07:48):
There's a camp that says, yes,viruses are alive.
The reason why some people saythat viruses are alive is that
they are able to reproduce, theyare able to evolve over time,
as we've seen with this littlecoronavirus.
And not only can they evolveover time, they also take over
(08:15):
the metabolism of cells to makemore viruses.
So some people say they'realive.
There's even more to that.
I'll come back to it.
There's another camp that saysno, they are not alive.
And the reason why is becausemost viruses are basically some
genetic programming, whetherit's RNA or DNA, encapsulated in
(08:37):
a protein coat.
And when that virus attacks acell, it unleashes that viral
software, that DNA or RNA, thatprogramming, to take over the
functioning of a cell andtherefore make more copies.
Now, I know that soundsparasitic.
The difference is a parasitehas cellular structure, it is
(09:00):
respiring, it is doingmetabolism, it is taking an
energy and it's doing it on itsown.
It's just extracting thisenergy from you or whatever
organism is infected.
A virus is reprogramming thecell based on genetic
information.
So in my mind, viruses aretypically not alive, they are
(09:21):
information.
They can be no more alive thanDNA.
Yeah, that's what I think Nowin biology.
One of the most beautifulthings about biology is that
it's messy, it's nuanced andthere's exceptions.
Yeah, there's exceptions outthere.
(09:41):
There are viruses that are huge.
They have genes for maybeseveral thousand different types
of proteins.
Some of them have rudimentarymetabolism.
Now, those particular virusesthat are very large, very
complex, maybe a hint ofmetabolism.
We can debate back and forth ofwhether or not they're alive or
(10:03):
not, and to me that's not quitethat important.
I would still say probablystill not alive because of the
lack of metabolism being drivenby information, but they're
definitely like kind of in thatgray area, or at least in my
mind they are.
Now here's the thing Virusesmay or may not be alive.
I'm going to say that they'renot alive, but they are part of
(10:26):
life.
So if you're out in space andyou find a space virus, guess
what you have to have Life.
Life has to be somewhere.
So viruses are derived fromlife, they are part of it, even
though they may not be living.
All right, I hope that worksout for everybody, okay.
(10:48):
Now, every now, now and then Iget some pretty good questions
from very insightful studentsthat you know they come up with
these really good questions andyou know you start defining life
based on these intro to biologybooks and a lot of them not a
lot, but a few.
Every now and then we'll say,hey, you know, what about
crystals, hurricanes, stars andplanets?
Are they alive?
(11:09):
And that's actually a prettyinteresting question, right?
Because in my classes I oftendefine life as a dissipative
structure, right?
So here's how a dissipativestructure works.
Imagine ice forming in yourfreezer.
Water is moving around randomly, all the individual molecules
are moving around randomly, andthen, as you remove heat, as you
(11:33):
remove energy from the water,there's not enough energy to
break those weak hydrogen bondsHolding the liquid water
together.
Those hydrogen bonds become setand ice crystals begin to form.
And when ice crystals begin toform, the water molecules go
from a state of high entropy tolow entropy as they become
(11:55):
organized.
Don't worry, we are notviolating any laws of
thermodynamics here.
This is a self-organizingdissipative system because what
happens is that, as the watermolecules arrange them into a
regular pattern.
When those hydrogen bonds areformed, it releases energy and
(12:16):
in fact it releases about sixkilojoules.
A mole for you know, foreverything of, for every mole of
water that's formed that'sabout 18 grams releases about
six kilojoules of energy.
So when ice is formed, it'sreleasing heat into the
environment.
That's why when you hit the dewpoint at night and water or ice
starts forming on the ground,nighttime temperatures often
(12:37):
stop declining so fast, becauseas the water condenses out of
the air, it releases energy, itreleases heat back into the
environment.
So ice is a self-organizeddissipative system.
It's a crystal.
And students have asked me hey,is that alive?
Because it's self-organizing?
And to me that's a reallyfantastic question.
Right?
The answer is they're not alive.
(12:59):
And the reason why is becausethings like a crystal, even
though they can reproduce, whatthey're not doing is
metabolizing.
They aren't taking ininformation from the environment
, reacting to it and doingmetabolism and releasing more
energy and, in fact, metabolismof life.
When a living thing takes inenergy from the environment and
(13:23):
uses information in his DNA toextract that energy from the
environment, it's much moreefficient than just pure abiotic
dissipation.
What I mean by that abioticdissipation is think of a
crystal forming, right?
Life is much more efficient atit.
But life is using information,right, to extract that energy
(13:45):
and create order at the level ofthe organism, right?
So that's why a crystal is notalive, even though it can
reproduce.
Hurricanes are also adissipative system.
They're created by energygradients and as hurricanes move
across the oceans, they aretransporting large amounts of
(14:06):
heat energy from the water to tonorthward areas.
And these hurricanesself-organize as well.
Stars and planets.
They form a circle, a ballright, a sphere, and as they
compact they're releasing energy.
And being in a sphere is a is astable structure that releases
energy.
So they are self-organized.
(14:27):
Minerals do the same thing aswell, but there's just no
coupling of information to thesemetabolic processes.
And people have pointed outthat.
You know.
The universe evolves.
Stars evolve, planets evolve,they do.
They do change over time.
Our star is changing over time.
Our planet is changing overtime.
Our planet is changing overtime.
(14:47):
It is evolving, but the waythey are evolving is not due to
changes in their information,this controlling their systems,
right.
They're just evolving todissipate more and more energy
and go toward equilibrium, right?
Okay, and then, oh, there'sfire.
Yeah, my inner Beavis just cameout.
(15:09):
I think a little bit there.
Fire, yes, yes, we used to stopstudying in college to go watch
Beavis and Butthead and I thinkI just dated myself.
Fire people say oh, you know,fire metabolizes, it breaks down
carbohydrates.
You know, fire metabolizes, itbreaks down carbohydrates.
(15:31):
You know the fuel of wood, andit releases energy into the
environment.
It can grow, it can reproduce.
The problem here is that fireis clearly not alive.
It does not self-organize.
Right, there's noself-organization.
There's no self-organization orrelease of entropy.
Fire is just this redox,reaction, reduction, oxidation.
(15:53):
Right, you're takingcarbohydrates and other things
inside the wood and you'rebasically making carbon dioxide
and water and some other thingsout of that and you're releasing
a ton of energy, but you aregetting absolutely no local
organization out of that.
And you're releasing a ton ofenergy, but you are getting
absolutely no local organizationout of that.
It is not a dissipativestructure at all.
And, yes, it does release moreenergy than life does, which is
(16:18):
using information to extractenergy and dissipate that into
the environment.
Okay, now that brings me to mynext point, and I don't think
that this is much of amisconception at all amongst
scientists, people studying theevolution of universe and life
in it.
But it sure, as a biologist,threw me for a loop, because
(16:42):
when you mentioned adaptation,as a biologist that has a very
precise meaning.
It basically means that apopulation is evolving in some
way to become better fit to itsenvironment so it can survive
and reproduce and pass on thosegenes to the next generation.
So an adaptation is part ofevolution, right?
(17:03):
You're changing to better fitto the environment and that is
driven by that filter of naturalselection, by changing the
information of your genetic code, of your genes.
Okay, so when I sawdissipation-driven adaptation, I
was like what, what does thatmean?
You know, dissipation-drivenadaptation?
(17:23):
So this isn't a misconceptionat all, this is just a
clarification and it took me awhile to figure this out as well
.
So, as I mentioned, things likecrystals, minerals, planets,
stars, hurricanes, these are alldissipative structures.
So what that means is they areself-organizing in a way that
(17:46):
releases energy to theenvironment.
They're increasing entropy.
I know, isn't it weird that theuniverse started off in low
entropy and is going toward highentropy?
But that pathway from lowentropy to high entropy, that's
where all the fun stuff happens,including life.
Okay, so what isdissipation-driven adaptation?
(18:07):
Yes, these things are adaptingin a way to become more stable.
So, as, like salt crystals formor water crystals form, they're
adapting in a way that theyrelease energy to the
environment.
And yet if it's a crystal, thatrepeating structure is
thermodynamically favorable, soit's going to last longer, right
(18:32):
, it's more stable.
But that adaptation is notdriven by algorithmic
information.
There's no, there's no code,there's no way of like okay,
crystal goes, okay, I need toput this molecule here, this
molecule here, this moleculehere.
We're going to use thismetabolic pathway to do like
okay, crystal goes, okay, I needto put this molecule here, this
molecule here, this moleculehere.
We're going to use thismetabolic pathway to do X, y and
Z.
No, these molecules are justarranging in the most stable
(18:53):
state they can and it's anadaptation in the sense that it
becomes more stable, notviolating any laws here, because
, like I said, it's dissipatingenergy.
So the dissipative structureitself is organizing because
that's more stable.
It's creating local order, butthe overall entropy of the
(19:13):
universe is is, uh, going up.
And then biological adaptationthat's providing some advantage
based on stored information.
Now for anybody out there thathas studied like information
theory oh man, that's kind ofblown my mind a little bit,
their way of defininginformation is very different
(19:36):
than the way you and I think ofinformation, but the way I'm
going to say information is wecan call it algorithmic
information.
So you've got a set ofinstructions that tell you what
to do under certaincircumstances.
Now, lastly, there's one morething that's always kind of
bothered me a little bit, and infact this is going to be the
(19:58):
basis of one of my next papersthat I hope to publish, maybe
later this spring.
I've got a trip to Costa Ricaand to and to colombia coming up
, so it's going to be a funspring.
This question that often comesup life as we know it or life as
we don't know it has becomequite popular now amongst
(20:19):
astrobiologists.
So as a biologist that studiedecology, evolution, physiology,
you know anatomy i've've lookedat biology from multiple scales
here I like to ask what do youmean?
Life as we don't know it, orwhat do you mean we have no idea
what alien life would look like?
(20:39):
That's a loaded question, right?
And it's also, I think peoplesay that in response to like, we
have to be open-minded aboutwhat life in the universe is
going to look like.
We only have a sample of one.
We do not know all thepossibilities out there and we
need to be very open-mindedabout what the potential of life
(21:03):
is out there in the universe.
Because, like I said, we hadthat N of one sample problem.
Right, we only got an exampleof one type of life.
That is very true and there issome humility in saying you know
, I don't know what life in theuniverse is going to look like,
but what kind of rubs me alittle bit.
The wrong way is, when peoplego, we have no idea what life
(21:27):
would look like elsewhere in theuniverse, and life on Earth is
not particularly useful forunderstanding life in the
universe.
I know, I've heard that and Ikind of take some issue here.
And here's why I think we canmake some predictions about
alien life or life in theuniverse in general.
Because if I say you know lifeis based on the natural laws of
(21:50):
the universe, right, we haveuniformitarianism.
The laws that operate on earthcan operate across the universe.
Those natural laws are going todrive convergent evolution.
Similar ecologies are going tolead to similar morphologies.
If you swim in water, you'regoing to look kind of like a
(22:11):
fish.
If you swim fast, you're goingto look more torpedo-like.
If you're going to have quickbursts of speed, you're going to
look more like a grouper withrounded wings, right, I would
imagine that life is going to bebilaterally symmetrical if it's
got a level of sophisticationclose to humans or animal life
on this planet.
So there's all kinds of naturallaws of the universe, like laws
(22:35):
of diffusion, fractal geometry,that can enable us to make
predictions about what lifemight look like.
To make predictions about whatlife might look like and to say
that life doesn't here on Earthis uninformative of life in the
universe.
I don't think that's right.
And here's another reason why.
(22:57):
Whether or not the Earth istotally unique is still out for
debate.
Right, it could be in the factthat it's got a moon, it's got
plate tectonics, which could bevery important for life.
But as we look out into theuniverse and we build a catalog
of planets, we do see Earth-likeplanets.
We see Earth-like planets inthe Goldilocks zone, where you
(23:19):
can have liquid water.
Now, life is definitelyprobably not limited to just the
Goldilocks zones.
We're going to hopefully findout about our ocean worlds and
the outer solar system ofEnceladus and Europa, but for
something like our planet, youneed this Goldilocks zone with
some rock water interface.
You're going to need ageologically active planet and
(23:41):
you know, life is going toprobably be based on carbon
chemistry and water and there'slots of reasons to believe that
and life is also probably goingto have a set of parameters that
is going to operate in.
Ph may not affect that verymuch, because we find life on
earth in almost every pH you canimagine.
(24:02):
But temperature matters.
You get too cold and thechemistry of life is going to
slow way, way, way, way downright Now.
That's not in itself superproblematic, except it becomes
harder to break the bonds andhave things moving around, right
.
So super cold becomesproblematic.
Let's go the other way,starting to get too hot.
(24:24):
I suspect that most life willnot exist beyond 150 degrees
Celsius.
Beyond those temperaturesthere's just too much kinetic
energy.
The molecules of life justcan't hold up.
They break apart.
So that's going to put a hardboundary on it.
All right, we already talkedabout needing water.
But also salinity might be aproblem too.
(24:47):
You need water for themolecules inside of cells to
move around and have thosechemical reactions.
As you add more and moreelectrolytes, you become saltier
and saltier, right.
The water loses water potential.
It doesn't move around as muchand all of those ions are gonna
start having problems.
(25:08):
They're gonna, you know, startattracting to all of your DNA or
whatever your informationstorage is.
Whatever molecules you're gonnahave, they're gonna start
affecting those chemistries alot.
So there's probably some hardlimits to salinity, probably
around 25 to 30 percent, maybe alittle bit higher or not, but
there are going to be limits tosalinity.
So those are some predictionsthat I think we can make.
(25:31):
We can also probably predictthat life in the universe is
going to be cellular.
The chemistries might bedifferent.
I still suspect they're allgoing to be based on carbon and
water, but maybe on titan we'llfind something different.
The reason why is, when we lookout in the universe, water is
everywhere, carbon is everywhere.
(25:52):
Guess what's everywhere elsetoo?
Silicon it's one of the mostabundant elements in our crust.
Okay, is life based on siliconon this planet?
No, and the reason why isbecause, unlike carbon, silicon
cannot make long chains.
It can't form complex moleculeslike carbon.
Can.
Carbon's in the Goldilocks zonehere.
(26:14):
So life?
That's why life is carbon-basedthere.
So, taking these firstprinciples, we can start to make
lots of predictions about life.
You want to live on land.
You got to deal with gravityand desiccation.
You want to grow big.
You probably have to have askeleton on the inside, an
endoskeleton like vertebrates,because if you have an
(26:36):
exoskeleton on a planet that'ssimilar size to earth, well, you
run into things like allometricscaling and you get bigger and
bigger and bigger.
The wall of your exoskeletongets thicker and thicker and
thicker.
At a very disproportionate ratewe would say that non-linear.
It gets thicker faster andyou're going to be.
There's a hard limit to how bigyou can get.
You'll probably need a closedcirculatory system if you want
(27:00):
to be big, because you got topump blood against gravity.
So, like I said, there's allkinds of things we can make
predictions about here.
You want to detect a light andthere's some things that can see
in the near infrared and thingsthat can see in the near
ultraviolet, but much beyond 700, you know, 730 nanometers gets
(27:22):
hard for life to detect becausethe that's infrared, by the way,
because that light, theelectromagnetic radiation, lacks
sufficient energy to, you know,cause a shape change in a
protein for you to detect it.
I mean feel it's heat, but wecan't see it very well as light
much beyond about 730 nanometersgo the other other way get up
(27:46):
into the ultraviolet and there'ssome birds and bees that can
see around 380, 350.
You get shorter than that andthe energy packs too much of a
punch right and you damage yourmolecules.
So, once again, no life willprobably detect light.
Okay, I'm really having funwith this and I could continue
(28:06):
on, but I'm actually gettingready to write a paper on this,
so I've actually I've got somemore information that I will
share once I get thatpublication out.
And uh, yeah, this has been fun.
So there it is.
There's some misconceptionsabout life.
One of them, not.
Some people have some very goodquestions, but you know, I
often hear our meals have somevery good questions, but you
know, I often hear our mulesalive and of course, they're
(28:28):
alive.
You know they're part of life.
Or viruses, alive or not?
Well, you know, probably not.
They're not dissipativestructure doing metabolism, you
know.
You know being controlled bysome form of information, um,
but they are a part of life,they're derived from life, right
, and then I don't think Italked about this.
I'm rambling a little bitbecause I forgot to write this
(28:49):
down.
Invariably, somebody might talkabout artificial life or
artificial intelligence, orartificial general intelligence
that might have the ability tobe self-aware or have
consciousness.
It can pass a Turing testability to be self-aware or have
(29:09):
consciousness, they can pass aTuring test, so to speak.
I think they can already dothat.
Or they may have agency.
Whether or not we considerartificial intelligence to be
alive or not, I think is more inthe realm of philosophers.
Once you get a cognition andagency and self-awareness, you
start asking questions.
Yeah, I, I think in some waysyou are alive.
(29:30):
The question is, it's adifferent type of life.
Uh, it's not organic life.
Like you know, I said, livingthings cells and organisms are
the living embodiment of theprocess of life.
Uh, but this ai, I think that'sgoing to be kind of in the
realm of philosophers.
But what I would say about thatis that, even if we consider AI
(29:54):
alive or not, it is still partof the planetary phenomena known
as life.
Okay, so, yeah, I got off tracka little bit there.
Yeah, I was kind of rambling alittle bit tonight and that's
okay.
I had some notes written down,but my brain is really thinking
(30:14):
about this, this theory of lifethat I hope to publish in a
couple of weeks.
Like I said, I got to get toCosta Rica first and whip this
paper intoelet.
Let my friends read it and makesure I'm not full of it, all
right.
Well, until next time.
This has been Tom Sykast, and Ipromise you this year will be
different.
I just bought a new microphone,a new preamp, and I'm really
(30:38):
looking forward to creating morepodcasts this year.
All right, I will post againsoon.
This is Tom Sykast.
Hello out there and welcome to another episode of Tom's
SciCast.
I'm your host, Tom Kennedy.
I know I've been gone a while,I've been busy and in fact next
week I'm actually leaving to goto Costa Rica with my buddy to
go find some sleeping lizardsand collect more data on them.
Well, since I've been gone,I've been doing a lot of work
actually.
I know I'm really diving intosome astrobiology and then I'm
(00:27):
hopefully going to publish somepapers on astrobiology.
Very excited about that and,yes, I will podcast that.
But as I've been doing someresearch and listening to lots
of other podcasts and readingbooks and reading up on the
whole field, I've realized thatthere's been a few
misconceptions out there and Igot to do something about this.
(00:49):
Right, I want to see if I candispel some of these
misconceptions, and the firstpaper I hope to publish on some
of these in March is actually atheory of life which I'm not
going to publish it quite yet asa podcast.
I'll wait till I actuallysubmit the paper.
But let's kind of jump intosome of these misconceptions and
(01:10):
of course, one of these has todo with what are living
organisms exactly, or what islife.
So my paper is going to be on,so I'm not going to jump into
all of it here.
But there's lots of definitionsout there on life.
If you took an intro to biologyyou may have gotten five
descriptive things about life,something about metabolism,
(01:32):
reproduction, evolution usingenergy.
If you took an AMP class, theirtextbook mentioned something
about moving and of coursethere's response to the
environment.
And if you're NASA, you call ita self-sustaining chemical
reaction capable of Darwinianevolution.
I kind of like that one, butthere's more to that.
(01:54):
But these definitions on somelevel are all problematic.
I mean, let's just take NASA'sdefinition, which I think is
actually pretty good as a simpledefinition.
It says a self-sustainingchemical reaction.
All right, I'm not exactly surewhat they mean by
self-sustaining.
I imagine it's somehowautocatalytic and can read the
(02:18):
environment right To take innutrients and information or
take in nutrients and energyfrom the environment and keep
going over time.
And if that's your system, well, it can't be an organism,
because organisms don't evolve.
An organism cannot evolvebecause we define evolution as a
change in allele frequencies.
(02:38):
It's the change in your DNA.
So a population that's thesmallest unit of evolution DNA.
So a population that's thesmallest unit of evolution.
So even NASA's definition theorganisms can't evolve.
So what is your system?
That is self-sustaining, thatis continually evolving through
natural selection.
I just thought I'd throw thatout there to get us warmed up
(02:59):
here Now listening to a fewpodcasts on astrobiology.
Of course, astrobiology ispre-paradigmatic, right, which
means there's not a reallyunderlying or overarching theme
or set of theories to unify thefield.
You go to physics you've gotrelativity, you've got Maxwell's
(03:19):
equations, you've got gravity,you've got relativity, you've
got quantum mechanics, but youhave these bases to unify the
field.
Biology has evolution bynatural selection, but
astrobiology is a little bitpreparative at it because we're
still trying to figure out whatlife is.
So all right.
(03:40):
So if something's live, ifthere's life, so what does life
do?
And of course I've alreadymentioned these things.
You know most people think thatlife reproduces, it evolves
over time.
There's some metabolism goingon, there's some
self-organization going on.
So invariably on these podcastslisten to some pretty
(04:00):
entertaining astrobiologists.
They would invariably ask aquestion like is a mule life?
Because a mule is sterile, itcannot reproduce.
Well, wait a second.
How about a person?
If they don't reproduce, arethey not life?
Of course mules are life,they're alive.
They're just a dead end of thatinformation driving that system
(04:22):
right.
There's still life.
They just can't reproduce.
The way I like to think of thisis a living organism is the
physical embodiment of life,right?
So life is a phenomenon, it's aprocess, it's doing these
things, a mule that's sterile,it's alive and it is part of
life.
(04:44):
Here's another misconceptionwhere somebody who hasn't
studied biology their whole lifemay make a simple mistake and
that's okay.
I mean, biology is complicatedand I'll tell you what I don't
get all of quantum physicseither, or relativity.
That stuff's pretty tough, it'svery mathematically driven and
I'm not that mathematicallyinclined I only went up through
(05:07):
differential equations incollege and so some of that
stuff escapes me.
But physicists often come tobiology and well, they don't get
some of the nuances justbecause biology really takes a
long time to understand it at abroad level.
And one of the interestingthings I've heard an
(05:28):
astrobiologist muse orcontemplate or throw out there
is they asked if parasites arealive.
And the reason why they askedif a parasite is alive is
because they made theobservation that many parasites
depend solely on a single host.
All right.
So the idea for these guys waslike well, maybe they're not
(05:51):
alive because they're like avirus.
A virus depends on a bacteriaor another cell.
Viruses depend on life.
I'll come back to that one in asecond because I know you guys
are ready to hear about theviruses.
But let me dispatch this thingreally quick about parasites.
Parasites are organisms.
They are made of cells.
Some parasites are as small asbacteria.
(06:13):
Some are eukaryotic cells, likePlasmodium falciparum that
causes malaria.
That's an intracellularparasite.
Malaria that's an intracellularparasite.
There are parasites that includemany, many types of worms,
tapeworms and liverworms and allthe flukes and trematodes and
nematodes so many differenttypes of parasitic worms.
(06:36):
They are organisms, they arecellular, they have cell
metabolism, they extractnutrients from their environment
and they reproduce, and some ofthem produce millions of eggs
over years.
And some of them are so highlyevolved like a tapeworm.
They don't have a mouth, theydon't need a mouth.
They're flat Hence flatworm andthey look like tape Hence
(06:59):
tapeworm and they absorb all thenutrients in your gut right
across their cuticle, rightacross their skin, right so they
don't even need a mouth.
They are just incrediblyspecialized animals or bacteria
or cells Right, so they'reincredibly specialized to live
in a very specific environmentwith very specific requirements.
(07:27):
Like some parasites can onlyattack one particular type of
host.
That's how specific some ofthese can get.
So they're totally alive, right, they're living, they're
metabolizing, they're they'rereproducing.
They're just highly derived,okay, okay now, um, I'll go
ahead and let's get to thisviruses.
There's a virus alive.
(07:48):
There's a camp that says, yes,viruses are alive.
The reason why some people saythat viruses are alive is that
they are able to reproduce, theyare able to evolve over time,
as we've seen with this littlecoronavirus.
And not only can they evolveover time, they also take over
(08:15):
the metabolism of cells to makemore viruses.
So some people say they'realive.
There's even more to that.
I'll come back to it.
There's another camp that saysno, they are not alive.
And the reason why is becausemost viruses are basically some
genetic programming, whetherit's RNA or DNA, encapsulated in
(08:37):
a protein coat.
And when that virus attacks acell, it unleashes that viral
software, that DNA or RNA, thatprogramming, to take over the
functioning of a cell andtherefore make more copies.
Now, I know that soundsparasitic.
The difference is a parasitehas cellular structure, it is
(09:00):
respiring, it is doingmetabolism, it is taking an
energy and it's doing it on itsown.
It's just extracting thisenergy from you or whatever
organism is infected.
A virus is reprogramming thecell based on genetic
information.
So in my mind, viruses aretypically not alive, they are
(09:21):
information.
They can be no more alive thanDNA.
Yeah, that's what I think Nowin biology.
One of the most beautifulthings about biology is that
it's messy, it's nuanced andthere's exceptions.
Yeah, there's exceptions outthere.
(09:41):
There are viruses that are huge.
They have genes for maybeseveral thousand different types
of proteins.
Some of them have rudimentarymetabolism.
Now, those particular virusesthat are very large, very
complex, maybe a hint ofmetabolism.
We can debate back and forth ofwhether or not they're alive or
(10:03):
not, and to me that's not quitethat important.
I would still say probablystill not alive because of the
lack of metabolism being drivenby information, but they're
definitely like kind of in thatgray area, or at least in my
mind they are.
Now here's the thing Virusesmay or may not be alive.
I'm going to say that they'renot alive, but they are part of
(10:26):
life.
So if you're out in space andyou find a space virus, guess
what you have to have Life.
Life has to be somewhere.
So viruses are derived fromlife, they are part of it, even
though they may not be living.
All right, I hope that worksout for everybody, okay.
(10:48):
Now, every now, now and then Iget some pretty good questions
from very insightful studentsthat you know they come up with
these really good questions andyou know you start defining life
based on these intro to biologybooks and a lot of them not a
lot, but a few.
Every now and then we'll say,hey, you know, what about
crystals, hurricanes, stars andplanets?
Are they alive?
(11:09):
And that's actually a prettyinteresting question, right?
Because in my classes I oftendefine life as a dissipative
structure, right?
So here's how a dissipativestructure works.
Imagine ice forming in yourfreezer.
Water is moving around randomly, all the individual molecules
are moving around randomly, andthen, as you remove heat, as you
(11:33):
remove energy from the water,there's not enough energy to
break those weak hydrogen bondsHolding the liquid water
together.
Those hydrogen bonds become setand ice crystals begin to form.
And when ice crystals begin toform, the water molecules go
from a state of high entropy tolow entropy as they become
(11:55):
organized.
Don't worry, we are notviolating any laws of
thermodynamics here.
This is a self-organizingdissipative system because what
happens is that, as the watermolecules arrange them into a
regular pattern.
When those hydrogen bonds areformed, it releases energy and
(12:16):
in fact it releases about sixkilojoules.
A mole for you know, foreverything of, for every mole of
water that's formed that'sabout 18 grams releases about
six kilojoules of energy.
So when ice is formed, it'sreleasing heat into the
environment.
That's why when you hit the dewpoint at night and water or ice
starts forming on the ground,nighttime temperatures often
(12:37):
stop declining so fast, becauseas the water condenses out of
the air, it releases energy, itreleases heat back into the
environment.
So ice is a self-organizeddissipative system.
It's a crystal.
And students have asked me hey,is that alive?
Because it's self-organizing?
And to me that's a reallyfantastic question.
Right?
The answer is they're not alive.
(12:59):
And the reason why is becausethings like a crystal, even
though they can reproduce, whatthey're not doing is
metabolizing.
They aren't taking ininformation from the environment
, reacting to it and doingmetabolism and releasing more
energy and, in fact, metabolismof life.
When a living thing takes inenergy from the environment and
(13:23):
uses information in his DNA toextract that energy from the
environment, it's much moreefficient than just pure abiotic
dissipation.
What I mean by that abioticdissipation is think of a
crystal forming, right?
Life is much more efficient atit.
But life is using information,right, to extract that energy
(13:45):
and create order at the level ofthe organism, right?
So that's why a crystal is notalive, even though it can
reproduce.
Hurricanes are also adissipative system.
They're created by energygradients and as hurricanes move
across the oceans, they aretransporting large amounts of
(14:06):
heat energy from the water to tonorthward areas.
And these hurricanesself-organize as well.
Stars and planets.
They form a circle, a ballright, a sphere, and as they
compact they're releasing energy.
And being in a sphere is a is astable structure that releases
energy.
So they are self-organized.
(14:27):
Minerals do the same thing aswell, but there's just no
coupling of information to thesemetabolic processes.
And people have pointed outthat.
You know.
The universe evolves.
Stars evolve, planets evolve,they do.
They do change over time.
Our star is changing over time.
Our planet is changing overtime.
Our planet is changing overtime.
(14:47):
It is evolving, but the waythey are evolving is not due to
changes in their information,this controlling their systems,
right.
They're just evolving todissipate more and more energy
and go toward equilibrium, right?
Okay, and then, oh, there'sfire.
Yeah, my inner Beavis just cameout.
(15:09):
I think a little bit there.
Fire, yes, yes, we used to stopstudying in college to go watch
Beavis and Butthead and I thinkI just dated myself.
Fire people say oh, you know,fire metabolizes, it breaks down
carbohydrates.
You know, fire metabolizes, itbreaks down carbohydrates.
(15:31):
You know the fuel of wood, andit releases energy into the
environment.
It can grow, it can reproduce.
The problem here is that fireis clearly not alive.
It does not self-organize.
Right, there's noself-organization.
There's no self-organization orrelease of entropy.
Fire is just this redox,reaction, reduction, oxidation.
(15:53):
Right, you're takingcarbohydrates and other things
inside the wood and you'rebasically making carbon dioxide
and water and some other thingsout of that and you're releasing
a ton of energy, but you aregetting absolutely no local
organization out of that.
And you're releasing a ton ofenergy, but you are getting
absolutely no local organizationout of that.
It is not a dissipativestructure at all.
And, yes, it does release moreenergy than life does, which is
(16:18):
using information to extractenergy and dissipate that into
the environment.
Okay, now that brings me to mynext point, and I don't think
that this is much of amisconception at all amongst
scientists, people studying theevolution of universe and life
in it.
But it sure, as a biologist,threw me for a loop, because
(16:42):
when you mentioned adaptation,as a biologist that has a very
precise meaning.
It basically means that apopulation is evolving in some
way to become better fit to itsenvironment so it can survive
and reproduce and pass on thosegenes to the next generation.
So an adaptation is part ofevolution, right?
(17:03):
You're changing to better fitto the environment and that is
driven by that filter of naturalselection, by changing the
information of your genetic code, of your genes.
Okay, so when I sawdissipation-driven adaptation, I
was like what, what does thatmean?
You know, dissipation-drivenadaptation?
(17:23):
So this isn't a misconceptionat all, this is just a
clarification and it took me awhile to figure this out as well
.
So, as I mentioned, things likecrystals, minerals, planets,
stars, hurricanes, these are alldissipative structures.
So what that means is they areself-organizing in a way that
(17:46):
releases energy to theenvironment.
They're increasing entropy.
I know, isn't it weird that theuniverse started off in low
entropy and is going toward highentropy?
But that pathway from lowentropy to high entropy, that's
where all the fun stuff happens,including life.
Okay, so what isdissipation-driven adaptation?
(18:07):
Yes, these things are adaptingin a way to become more stable.
So, as, like salt crystals formor water crystals form, they're
adapting in a way that theyrelease energy to the
environment.
And yet if it's a crystal, thatrepeating structure is
thermodynamically favorable, soit's going to last longer, right
(18:32):
, it's more stable.
But that adaptation is notdriven by algorithmic
information.
There's no, there's no code,there's no way of like okay,
crystal goes, okay, I need toput this molecule here, this
molecule here, this moleculehere.
We're going to use thismetabolic pathway to do like
okay, crystal goes, okay, I needto put this molecule here, this
molecule here, this moleculehere.
We're going to use thismetabolic pathway to do X, y and
Z.
No, these molecules are justarranging in the most stable
(18:53):
state they can and it's anadaptation in the sense that it
becomes more stable, notviolating any laws here, because
, like I said, it's dissipatingenergy.
So the dissipative structureitself is organizing because
that's more stable.
It's creating local order, butthe overall entropy of the
(19:13):
universe is is, uh, going up.
And then biological adaptationthat's providing some advantage
based on stored information.
Now for anybody out there thathas studied like information
theory oh man, that's kind ofblown my mind a little bit,
their way of defininginformation is very different
(19:36):
than the way you and I think ofinformation, but the way I'm
going to say information is wecan call it algorithmic
information.
So you've got a set ofinstructions that tell you what
to do under certaincircumstances.
Now, lastly, there's one morething that's always kind of
bothered me a little bit, and infact this is going to be the
(19:58):
basis of one of my next papersthat I hope to publish, maybe
later this spring.
I've got a trip to Costa Ricaand to and to colombia coming up
, so it's going to be a funspring.
This question that often comesup life as we know it or life as
we don't know it has becomequite popular now amongst
(20:19):
astrobiologists.
So as a biologist that studiedecology, evolution, physiology,
you know anatomy i've've lookedat biology from multiple scales
here I like to ask what do youmean?
Life as we don't know it, orwhat do you mean we have no idea
what alien life would look like?
(20:39):
That's a loaded question, right?
And it's also, I think peoplesay that in response to like, we
have to be open-minded aboutwhat life in the universe is
going to look like.
We only have a sample of one.
We do not know all thepossibilities out there and we
need to be very open-mindedabout what the potential of life
(21:03):
is out there in the universe.
Because, like I said, we hadthat N of one sample problem.
Right, we only got an exampleof one type of life.
That is very true and there issome humility in saying you know
, I don't know what life in theuniverse is going to look like,
but what kind of rubs me alittle bit.
The wrong way is, when peoplego, we have no idea what life
(21:27):
would look like elsewhere in theuniverse, and life on Earth is
not particularly useful forunderstanding life in the
universe.
I know, I've heard that and Ikind of take some issue here.
And here's why I think we canmake some predictions about
alien life or life in theuniverse in general.
Because if I say you know lifeis based on the natural laws of
(21:50):
the universe, right, we haveuniformitarianism.
The laws that operate on earthcan operate across the universe.
Those natural laws are going todrive convergent evolution.
Similar ecologies are going tolead to similar morphologies.
If you swim in water, you'regoing to look kind of like a
(22:11):
fish.
If you swim fast, you're goingto look more torpedo-like.
If you're going to have quickbursts of speed, you're going to
look more like a grouper withrounded wings, right, I would
imagine that life is going to bebilaterally symmetrical if it's
got a level of sophisticationclose to humans or animal life
on this planet.
So there's all kinds of naturallaws of the universe, like laws
(22:35):
of diffusion, fractal geometry,that can enable us to make
predictions about what lifemight look like.
To make predictions about whatlife might look like and to say
that life doesn't here on Earthis uninformative of life in the
universe.
I don't think that's right.
And here's another reason why.
(22:57):
Whether or not the Earth istotally unique is still out for
debate.
Right, it could be in the factthat it's got a moon, it's got
plate tectonics, which could bevery important for life.
But as we look out into theuniverse and we build a catalog
of planets, we do see Earth-likeplanets.
We see Earth-like planets inthe Goldilocks zone, where you
(23:19):
can have liquid water.
Now, life is definitelyprobably not limited to just the
Goldilocks zones.
We're going to hopefully findout about our ocean worlds and
the outer solar system ofEnceladus and Europa, but for
something like our planet, youneed this Goldilocks zone with
some rock water interface.
You're going to need ageologically active planet and
(23:41):
you know, life is going toprobably be based on carbon
chemistry and water and there'slots of reasons to believe that
and life is also probably goingto have a set of parameters that
is going to operate in.
Ph may not affect that verymuch, because we find life on
earth in almost every pH you canimagine.
(24:02):
But temperature matters.
You get too cold and thechemistry of life is going to
slow way, way, way, way downright Now.
That's not in itself superproblematic, except it becomes
harder to break the bonds andhave things moving around, right
.
So super cold becomesproblematic.
Let's go the other way,starting to get too hot.
(24:24):
I suspect that most life willnot exist beyond 150 degrees
Celsius.
Beyond those temperaturesthere's just too much kinetic
energy.
The molecules of life justcan't hold up.
They break apart.
So that's going to put a hardboundary on it.
All right, we already talkedabout needing water.
But also salinity might be aproblem too.
(24:47):
You need water for themolecules inside of cells to
move around and have thosechemical reactions.
As you add more and moreelectrolytes, you become saltier
and saltier, right.
The water loses water potential.
It doesn't move around as muchand all of those ions are gonna
start having problems.
(25:08):
They're gonna, you know, startattracting to all of your DNA or
whatever your informationstorage is.
Whatever molecules you're gonnahave, they're gonna start
affecting those chemistries alot.
So there's probably some hardlimits to salinity, probably
around 25 to 30 percent, maybe alittle bit higher or not, but
there are going to be limits tosalinity.
So those are some predictionsthat I think we can make.
(25:31):
We can also probably predictthat life in the universe is
going to be cellular.
The chemistries might bedifferent.
I still suspect they're allgoing to be based on carbon and
water, but maybe on titan we'llfind something different.
The reason why is, when we lookout in the universe, water is
everywhere, carbon is everywhere.
(25:52):
Guess what's everywhere elsetoo?
Silicon it's one of the mostabundant elements in our crust.
Okay, is life based on siliconon this planet?
No, and the reason why isbecause, unlike carbon, silicon
cannot make long chains.
It can't form complex moleculeslike carbon.
Can.
Carbon's in the Goldilocks zonehere.
(26:14):
So life?
That's why life is carbon-basedthere.
So, taking these firstprinciples, we can start to make
lots of predictions about life.
You want to live on land.
You got to deal with gravityand desiccation.
You want to grow big.
You probably have to have askeleton on the inside, an
endoskeleton like vertebrates,because if you have an
(26:36):
exoskeleton on a planet that'ssimilar size to earth, well, you
run into things like allometricscaling and you get bigger and
bigger and bigger.
The wall of your exoskeletongets thicker and thicker and
thicker.
At a very disproportionate ratewe would say that non-linear.
It gets thicker faster andyou're going to be.
There's a hard limit to how bigyou can get.
You'll probably need a closedcirculatory system if you want
(27:00):
to be big, because you got topump blood against gravity.
So, like I said, there's allkinds of things we can make
predictions about here.
You want to detect a light andthere's some things that can see
in the near infrared and thingsthat can see in the near
ultraviolet, but much beyond 700, you know, 730 nanometers gets
(27:22):
hard for life to detect becausethe that's infrared, by the way,
because that light, theelectromagnetic radiation, lacks
sufficient energy to, you know,cause a shape change in a
protein for you to detect it.
I mean feel it's heat, but wecan't see it very well as light
much beyond about 730 nanometersgo the other other way get up
(27:46):
into the ultraviolet and there'ssome birds and bees that can
see around 380, 350.
You get shorter than that andthe energy packs too much of a
punch right and you damage yourmolecules.
So, once again, no life willprobably detect light.
Okay, I'm really having funwith this and I could continue
(28:06):
on, but I'm actually gettingready to write a paper on this,
so I've actually I've got somemore information that I will
share once I get thatpublication out.
And uh, yeah, this has been fun.
So there it is.
There's some misconceptionsabout life.
One of them, not.
Some people have some very goodquestions, but you know, I
often hear our meals have somevery good questions, but you
know, I often hear our mulesalive and of course, they're
(28:28):
alive.
You know they're part of life.
Or viruses, alive or not?
Well, you know, probably not.
They're not dissipativestructure doing metabolism, you
know.
You know being controlled bysome form of information, um,
but they are a part of life,they're derived from life, right
, and then I don't think Italked about this.
I'm rambling a little bitbecause I forgot to write this
(28:49):
down.
Invariably, somebody might talkabout artificial life or
artificial intelligence, orartificial general intelligence
that might have the ability tobe self-aware or have
consciousness.
It can pass a Turing testability to be self-aware or have
(29:09):
consciousness, they can pass aTuring test, so to speak.
I think they can already dothat.
Or they may have agency.
Whether or not we considerartificial intelligence to be
alive or not, I think is more inthe realm of philosophers.
Once you get a cognition andagency and self-awareness, you
start asking questions.
Yeah, I, I think in some waysyou are alive.
(29:30):
The question is, it's adifferent type of life.
Uh, it's not organic life.
Like you know, I said, livingthings cells and organisms are
the living embodiment of theprocess of life.
Uh, but this ai, I think that'sgoing to be kind of in the
realm of philosophers.
But what I would say about thatis that, even if we consider AI
(29:54):
alive or not, it is still partof the planetary phenomena known
as life.
Okay, so, yeah, I got off tracka little bit there.
Yeah, I was kind of rambling alittle bit tonight and that's
okay.
I had some notes written down,but my brain is really thinking
(30:14):
about this, this theory of lifethat I hope to publish in a
couple of weeks.
Like I said, I got to get toCosta Rica first and whip this
paper intoelet.
Let my friends read it and makesure I'm not full of it, all
right.
Well, until next time.
This has been Tom Sykast, and Ipromise you this year will be
different.
I just bought a new microphone,a new preamp, and I'm really
(30:38):
looking forward to creating morepodcasts this year.
All right, I will post againsoon.
This is Tom Sykast.
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