September 21, 2011 • 25 mins
Why haven't males evolved to not have nipples? Many newborns lactate "witches milk" soon after birth. Can men lactate? Listen in as Cristen and Caroline tackle these questions and more in this episode.
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Speaker 1 (00:00):
Brought to you by the reinvented two thousand twelve Camray.
It's ready. Are you welcome to stuff mom never told you?
From house Stop works dot Com. Hello, and welcome to
the podcast. I'm Kristen and I'm Caroline. So today we
(00:21):
are talking about nipples, all right, just gonna put it
out there. Uh, and the question of why men have
them to begin with, because you know, with all the
we talked, we've talked about breastfeeding before, bras, Uh, it
doesn't seem necessary for men to have no, Yeah, they
seem pretty useless. Yeah, but um, yeah, they basically to
(00:44):
make a very quick answer for all of this. To
sum it up at the beginning, Yeah, men have nipples
because women have nipples and vice versa. And that is
almost a direct quote from Andrew M. Simon's biology professor
at Carlton University, who's talking to a scientific amount can
about this question. And yeah, they've males have them because
(01:05):
females have them, and they're not fastigial like you might
think too, which we will explain very shortly. Right, So
at the dawn of your conception, Um, when we are
these little amorphous a sexual blobs in the womb, embryos,
embryos or embryos. I like to think of it as blobs,
(01:27):
little sacks of cells. Um, we are actually made up
of a bunch of the same stuff, and it's not
until a little bit later in the development. As many
of you, I'm sure are aware, that we actually have
a sex determined whether we're male or female, and so
basically we we get a lot of the same stuff
and nipples just never fell off, right, um. And it
(01:50):
all has to do with the timeline of how are
twenty three pairs of chromosomes express themselves as the the
embryonic blob develops into a full, full blown fetus, full full,
full blown yes. Um, well, yeah, Well, the thing is
that nipples aren't a sex linked characteristic. Everybody gets them.
(02:14):
Cecil Atoms over at the Straight Dope said that they
are sexually neutral, and nipples develop around the third week,
whereas the bits and pieces pertaining to boys or girls
don't develop for another couple of weeks after that the
euro genital systems. Yep, but the thing is too in
those uh, those early weeks before the like you said,
(02:36):
the seventh week, when that um, the one pair of
chromosomes that determines your your biological sex expresses the all
the embryos have the exact same parts, and for that reason,
women actually will retain remnants of the vas deferens that
(02:58):
we you know that started building back in our embryo days. Yes,
that's our blob days. Yeah, um yeah. We all get
twenty three pairs of chromosomes, as you may have heard, um,
and one pair, just one pair, determines whether we're male
or female, and the other two supply our standard equipment. Um.
(03:19):
That one pair of sex chromosomes programs the rest for
maleness or femaleness. And before they kick in, we're equipped
with both sets of plumbing exactly right. And um. The
genes that are not sexually, the autosomes, those are the
ones that will express into nipples, but among other things,
(03:39):
of course, not just covered in nipples. Most of us
and this nipples developed after three or four weeks of conception.
And what happens is we first developed something called a
milk line. I hadn't heard about this before. I hadn't either,
And it's a ridge of tissue that runs from your
upper chest to the navel and then veers down towards
(03:59):
the girl oin and stops on the upper thigh and
it um. It basically is this line of tissue that
nipples developed from. And it's more than two. Okay, it
just so happens that as we develop only two typically
you know the bear we normally associate as as should
(04:20):
be there are the ones that remained. But that's not
always the case. Now this sort of maybe have to
rethink my entire world. I didn't realize that this this existed.
I mean, I've heard of people having extra nipples before,
but I thought that's weird. How does that happen? And
I didn't realize before I read the stuff about the
milk line that that's why. So it's not uncommon for
(04:41):
hints of nipples pat nipples passed to hang around disguised
as a freckle or a mole um. They're called super
numerary nipples. Did I did? I pronounced that supernume a
lot of um. And yeah, you might just think that
you have a really big mole on your boob area
(05:02):
or your chest, abdomen wherever it could be. It could
be a spare nipple, yeah, because that's why I I
do know someone with an extra yeah, but with a
tiny I mean, you can barely tell that they're they're nipples. Um,
and they're directly below where um, you know, his actual
(05:23):
nipples are. And uh yeah, I always thought that it
was an extra growth, but no, it just means that they,
you know, they had an overly developed milk ridge line,
which is why you wouldn't have one, you know, probably
hanging out right on top of your belly button there,
you know, it would be more in parallel line. But
(05:43):
typically mammals. Fun fact also about nipples is that usually
mammal mammalian nipples come in even numbers. Oh yeah, I
think so. We have two arms, two legs most of us.
There is one possem and I forget which which exact
type of possumatists that comes with thirteen nipples all in
a in a nice story. Oh yeah, there's one right
(06:04):
in the middle, like a baker's, doesn't you know. Yeah, Well,
anyway back to people. Um, the American Journal of Primatology,
well okay, well this is primatology. They were talking about monkeys,
but they talked about humans too, And in the American
Journal of Primatology in two thousand they said, uh, most
(06:24):
supernumerary nipples result from a failure to terminate mammary bud development.
So you know, it's not like they're hurting you, just
that you know, your body was like, I've got other
things to do. And it's linked to what it's something
called the hawks is gene It's all about gene expression.
And you know how how fully it uh, you know,
the genes will express themselves and either stop the the
(06:47):
milk ridge development or keep it going too long. Yeah,
the hawks genes set up the head to tail organization.
And the reason why supernumerary nipples are relevant in this
discussion of male nipple I want to say nippleage male. Uh.
The reason why it's relevant is because, according to the
(07:09):
European Journal Pediatrics, there is a higher prevalence of supernumerary
nipples on the left side of the body and in men. Yeah,
so you should be running to a mirror right now.
Those those freckles, You've got freckles on your abdomen. I'm
just saying it could be could be an extra set
from the the old milk line. Right. Um. Now, kind
(07:33):
of back to more of why men have nipples in
the first place. Um, Basically, there's this talk of genetic correlation.
The idea of two traits shared genetic basis right, because
going back to our conversation about UM, the chromosomes we have,
you know, women developed breasts because of that, you know
(07:56):
that twenty three pair of chromosomes, the double X. That
UM is linked to sexually dimorphic traits, which are basically,
you know, the obvious physical traits. You know, men grow up,
you know, developing penises, women developing v China's things like
that that separate UM males and females. But nipples are
(08:18):
not one of those things. It's a genetic correlation. And basically,
in order for men to from an evolutionary standpoint, for
men to not have nipples, it would have to be
um more beneficial for them reproductive ones to not have them, right,
it would have to be doing some damage or hurting
(08:39):
them in some way, or be more um evolutionarily advantageous.
There we go to not have them. And since basically
essentially it doesn't matter if men have nipples. So but
since it's a traite, a genetic trait that men and
women share, and it's so important for women to have nipples,
then it would almost be too much work for us
(09:01):
too for men to evolve losing nipples. Right, So it's
more that there is a lack of selection against them
rather than a specific selection for them. Right. And explaining
all of this to Scientific American, a mamalogist named Douglas
Long says, it's a lot more difficult to lose an
organ than to develop an organ. And he compared it
(09:24):
to the reason why we have to nails, like, we
don't necessarily need toenails at all to claw and dig trees.
You know, at least we have something to paint. Yes, exactly,
who doesn't need red fingernails for whatever reason? Um? He Actually,
Douglas Long did say something that I thought was funny
when I did more reading. He said, not one male
(09:45):
mammal has been shown to lactate, And then everything else
I read was like, oh, well, yeah, we've got these bats, yeah,
and goats and things. Um. Jared Diamond, he's an author
and physiologist. He pointed out in a nineteen any five
article for Discover magazine that the Dyak fruit bat in
Southeast Asia can spontaneously lactate, and that is one of
(10:08):
the only examples of a male mammal that has been
seen to lactate, just under no sort of laboratory um
conditions at all. Because there have been male goats and
I believe male cows that have lactated, but that's because
they were induced with hormone that's stimulated lactation. And one
(10:33):
one fun nipple fact stallions male horses they don't have
nipples at all. They don't neither do platypuses. Yeah, the platypus,
they were so gross. Oh I thought it was kind
of cool. Still Okay, it talks about how they don't
have nipples. They just sort of like leech milk. Yeah,
the milk just comes out of their pores and then
(10:54):
their little baby platypus puses look it up. They don't
like it, take it away. Um, okay, well back to again,
back to people, all right. So Jared Diamond in his
article also discussed actual male human lactation. Um, it's sort
(11:15):
of It can occur when the pituitary gland gets all upset,
and that can happen when you face starvation. And so
he pointed to survivors of Nazi concentration camps and Japanese
prisoner of war camps who had been starving and when
they got out, they experienced lactation when they began to recover, right,
(11:35):
And that's because the pituitary gland in the brain stimulates
the production of a hormone called prolactin. And when we
produced prolactin, it triggers alveoli in breast tissue to produce milk.
And the reason why those concentration camp prisoners in the
prisoners of war experienced spontaneous lactation was because when your
(12:00):
body recovers from starvation, your glands recover a lot faster
than your liver, which absorbs hormones. So basically they have
the spike in prolactin and lactation which can also happen
in newborn's right. Yeah, this is called witches milk. And
it's when you know the baby is first born, it's
(12:23):
still has a lot of its mother's estrogen pumping through it,
and so it can just spontaneously lactate when it's born,
and this can continue for a weaker So yeah, because
and that's just when you're pregnant, prolactin levels surged ten
times higher than normal and that can seep into the
placenta and you might give birth to a lactating baby. Yeah,
(12:45):
I'm just gonna adopt dogs. Um, but it's not just
pregnancy or starvation that can cause men to spontaneously lactate.
Diamond theorizes that some combination of manual nipple stimulation and
hormone injections may develop a father's latent potential to make milk.
And in Scientific American they touched on this issue in
(13:08):
again in two thousand seven, UH and they pointed out
that medical anthropologists Dana Raphael an into chronologist Robert Greenblatt
agreed that men couldn'tduce flactation by stimulating their nipples. So
I am never giving another titty twister to anyone. Well,
and that's because when um, you know, when when a
baby latches on to a nipple, it stimulates sees mechana
(13:33):
receptors in the brain that gets the whole pituitary glamb prolactin.
I'll be only process going. But that does not necessarily
mean that you know, if you were if you were
to give um, if you were to give a man
a baby and the baby was yes, and the bay
were to latch onto that male nipple, because it does
(13:53):
happen sometimes. Um, you know, babies just they see a
nipple and they will latch on if they're hungry. But
that doesn't necessarily mean that all of a sudden, you know,
the faucets will will turn on and and a mail
will just spontaneously lactate. It definitely takes um, takes a
little bit of time. There was one study, this was
(14:14):
out of Canada. They were looking at adoptive mothers who
had adopted infants and whether or not they could sort
of stimulate uh, lactation through using breast pumps over time
and um contact with the infant to get their bodies
producing the prolactin. And they were able to stimulate it
in about I think it was thirty of the mothers.
(14:36):
But it kind of just goes to show that a,
you know, women already have you and I have, even
with though we're not pregnant, have a third more prolactin
running through our bodies. Uh so we already have a
head start over men. And even with that, it's still
hard to to just automatically jump start lactation, right. Dr
(14:56):
Jack Newman, who's a breastfeeding expert, says, basically, know hormone
spy cast you occur in order to produce milk, and
that brings us back to the pituitary gland which we
said secretes prolactin, and he actually Dr Newman points out that, hey,
it could be a pituitary tumor just while you're while
you're lactating um. But there's a lot of other stuff.
(15:17):
There's medications like thorazine, which was a popular antipsychotic in
the mid twentieth century, which affected the pituitary gland and
cause a spike in prolactin production, and certain issues like
testosterone deficiencies with male hypogonadism can cause a condition called galactia,
which is basically spontaneous lactation like we keep um talking about.
(15:41):
And if you're curious as to whether or not the
milk that men can produce is similar to the milk
that women produce, as a matter of fact, in nine
study conducted at the University of Western Australia confirms, but
yes it is. It had very similar contents to um
female levels of protein, lactose, and electrolytes in this in
(16:04):
this man's milk. It's usually just it's not so much
the content of the milk but the volume. Even when
men do lactate, they're not you know, they're not filling
up baby bottles. A writer from Slate actually did a
little experiment. He wrote about his journey into male actation.
He bought a breast pump manual not I don't know, motorized,
(16:26):
the electric little lact ones I don't know, and m
he you know, he just didn't have any success and
he gave up. He I don't think he liked the
idea of having to pump his body full of furmans
and take a three hour three hour breaks. And right
he was like, I can either take these these medications
that will you know, mess with my pituitary grooland and
(16:47):
possibly made me kind of crazy and lactate. And he
tried to take um finn a Greek which is this
uh like a herbal supplement. You can get it um
any natural food store that's supposed to do a similar thing,
like a lot of um, you know, like maybe like
neonatal uh. Herbal supplements will contain Finn agreed to help
stimulate lactation. And he was taking it like three times
(17:10):
a day, drinking fun of Greek tea and yeah, nothing,
nothing happened. And he determined that maybe it was the
fact that he didn't have an infant. I mean, he's
a single guy and he didn't have any any little
life depending on him and his like patition, and it
was interesting, like um. Charles Darwin, not not too surprisingly,
(17:32):
was fascinated by this this uh this whole male nipple conundrum,
and in the Descent of Man he posited that men
used to evolutionary or evolutionary ancestors. Men and women used
to uh suckle our young and it was only once
our litters got smaller to where it could be managed
(17:54):
at breastfeeding could be managed by just one of the
caregivers than men gradually stopped breastfeeding. But we still just have,
you know, they still just have the remnants because like
I said, it's not um. Male nipples are not vestigial
because they do contain um, breast tissue, the blood, vessels, nerves, alveoli.
(18:16):
They can you know, men can lactate, yes, and they
do and they do in Central Africa, the the Aca tribe.
I think that's a prous it um. The Guardian and
two thousand five reported on American anthropologist Barry Hewlett who
lived with this tribe and studied them, and he discovered
that the men nurse their infants when the mothers are
(18:39):
you know, away doing whatever. And part of this is
their whole culture is so fascinating to to us as
Westerners because all of their roles are completely fluid. They
have no problem trading off cooking, hunting, caring, caring for
the babies. He even pointed out, um that the men
would you know, strap the babies to their sides and
go down to the equivalent, but the tribal equivalent of
(19:01):
the bar, and hang out with their buddies with the baby.
It wasn't you know, it wasn't weird because they don't
view children as burdens something to you know, waste resources
or whatever, take up resources. I guess I should say, um,
they look at children as a blessing and so everybody
wants to pitch in and take care of the babies,
(19:23):
including the dads who have been known to la date. Well.
It's also interesting because you know, the women are away
from the household because they're seen as just as adequate
hunters and gatherers, you know, in this in this culture
as the men are. And according to the anthropologists, he
said that men are with their infants forty seven percent
(19:43):
of the time, which he by his calculations, was basically
the most dedicated fatherhood of any culture on the planet. Um.
Which is kind of fascinating that that these men would
um possibly be lack hating more than say, fathers in America,
which don't spend as much time with their children. So UM,
(20:06):
so buck up, guys, just if if you spend a
little more time with your family, maybe you too could
breast face Well, I mean, it's just it's a It's
an interesting example because Jared Diamond, who wrote that Discover
magazine article that you were talking about earlier, uh, says
that the evolutionary conditions that would favor male lactation would include, UM,
a litter of infants that constitute a big burden to nourish,
(20:29):
so you know, you would need um more more hands
on deck, monogamous male and female pairers, high confidence of
males in their paternity, and hormone preparation of fathers for
eventual lactation while their mate is still pregnant. They expect
to do that. And it sounds like to some degree
maybe this pygmy group in Central Africa, UM, I don't know,
(20:51):
maybe perhaps those those conditions are more ripe in the
less gender segregated society. They don't see it as weird.
If the women can do what the men can do
it and vice versa. Yeah, and because guys, have you
got the equipment and you might actually have more nipples
than we do on the left side of your body.
I'm so glad I know about milk ridges now to
(21:12):
not really though I don't really I didn't want I
didn't really want to know it. What fascinating nipples. Anyway,
with that, Carolina is going to have to go through
a little bit of a therapy from all of this
male lactation research. Um. And of course now we would
like specifically letters from men who pops possibly lactated. Is
(21:37):
there anyone out my gosh that would be okay, that
would be fascinated actually to actually hear from one of
you guys. I mean it's like especially fathers out there,
who have you know, dealt with because it seems like
this issue is a lot more pertinent for for dads
who have wondered like, well could I, you know, could
I help my milady out and with the breastfeeding duties?
Well you maybe maybe maybe let's not talk to some
(21:59):
the AKA people in Central Central Africa maybe have some
tips and in the meantime, you can email us at
Mom's stuff at how stuff works dot com. And we
got a couple of emails to read right now. So
I have an email here from Marie in our in
response for episode on women in science. She says, I'm
(22:20):
a third year grad student in microbiology immunology research, and
I'm wondering about the cultural influence on women in the workplace.
A huge proportion of research labs, at least in the biomedfield,
is international. Many of them are women. We have a
Japanese female post doc and a Chinese female research associate,
but I haven't exactly counted the proportion. Are there other
(22:41):
countries that still discourage women in science? In my own experience,
I've never felt at all any discouragement to go into
sciences because of being a woman. On the contrary, many
of my science teachers were women. I hear all this
talk about gender bias, but I've never seen it in action.
Of course, the biomedical sciences are different from other fields.
I've read somewhere that it's engineering and compute your sciences
that are the most skewed, And yes, she is right.
(23:03):
Engineering has ze lowest proportion of female students least in
higher education. So thank you for your input. Marie and
I have an email from Lorian. This is in response
to our pregnancy test podcast and my enthusiasm for the
self exam. The pelvic self excuse yeah um, she said.
(23:26):
There is a birth control method called the Fertility Awareness
Method or FAM, which uses basil, body temperature, cervical fluid,
and the position and openness of your service to chart
when you're ovulating. It's very easy once you learn, and
takes really only seconds a day to take your temperature,
note what your cervical fluid is doing, or to check
your service. If you're trying to conceive, you can concentrate
(23:49):
your efforts, and if you're trying to avoid pregnancy, you
can avoid the fertile window. There is a wonderful book
called Taking Charge of Your Fertility that talks about it
in detail. I didn't do a pelvic selfing ZAMBA because
I was charting my cycle. I was able to get
my first positive test nine days after ovulation, which was
quite early. My midwife was so confident in my days
after seeing my chart, we opted not to do an
(24:11):
early dating ultrasound. It's really a neat method and has
empowered me and knowledge of my body utili awareness. I
need to look more into that. Uh. And of course
our email is mom Stuff at how stuff works dot
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(24:33):
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(24:58):
brought to you by the reinvented two thousand love Camery.
It's ready, are you
Brought to you by the reinvented two thousand twelve Camray.
It's ready. Are you welcome to stuff mom never told you?
From house Stop works dot Com. Hello, and welcome to
the podcast. I'm Kristen and I'm Caroline. So today we
(00:21):
are talking about nipples, all right, just gonna put it
out there. Uh, and the question of why men have
them to begin with, because you know, with all the
we talked, we've talked about breastfeeding before, bras, Uh, it
doesn't seem necessary for men to have no, Yeah, they
seem pretty useless. Yeah, but um, yeah, they basically to
(00:44):
make a very quick answer for all of this. To
sum it up at the beginning, Yeah, men have nipples
because women have nipples and vice versa. And that is
almost a direct quote from Andrew M. Simon's biology professor
at Carlton University, who's talking to a scientific amount can
about this question. And yeah, they've males have them because
(01:05):
females have them, and they're not fastigial like you might
think too, which we will explain very shortly. Right, So
at the dawn of your conception, Um, when we are
these little amorphous a sexual blobs in the womb, embryos,
embryos or embryos. I like to think of it as blobs,
(01:27):
little sacks of cells. Um, we are actually made up
of a bunch of the same stuff, and it's not
until a little bit later in the development. As many
of you, I'm sure are aware, that we actually have
a sex determined whether we're male or female, and so
basically we we get a lot of the same stuff
and nipples just never fell off, right, um. And it
(01:50):
all has to do with the timeline of how are
twenty three pairs of chromosomes express themselves as the the
embryonic blob develops into a full, full blown fetus, full full,
full blown yes. Um, well, yeah, Well, the thing is
that nipples aren't a sex linked characteristic. Everybody gets them.
(02:14):
Cecil Atoms over at the Straight Dope said that they
are sexually neutral, and nipples develop around the third week,
whereas the bits and pieces pertaining to boys or girls
don't develop for another couple of weeks after that the
euro genital systems. Yep, but the thing is too in
those uh, those early weeks before the like you said,
(02:36):
the seventh week, when that um, the one pair of
chromosomes that determines your your biological sex expresses the all
the embryos have the exact same parts, and for that reason,
women actually will retain remnants of the vas deferens that
(02:58):
we you know that started building back in our embryo days. Yes,
that's our blob days. Yeah, um yeah. We all get
twenty three pairs of chromosomes, as you may have heard, um,
and one pair, just one pair, determines whether we're male
or female, and the other two supply our standard equipment. Um.
(03:19):
That one pair of sex chromosomes programs the rest for
maleness or femaleness. And before they kick in, we're equipped
with both sets of plumbing exactly right. And um. The
genes that are not sexually, the autosomes, those are the
ones that will express into nipples, but among other things,
(03:39):
of course, not just covered in nipples. Most of us
and this nipples developed after three or four weeks of conception.
And what happens is we first developed something called a
milk line. I hadn't heard about this before. I hadn't either,
And it's a ridge of tissue that runs from your
upper chest to the navel and then veers down towards
(03:59):
the girl oin and stops on the upper thigh and
it um. It basically is this line of tissue that
nipples developed from. And it's more than two. Okay, it
just so happens that as we develop only two typically
you know the bear we normally associate as as should
(04:20):
be there are the ones that remained. But that's not
always the case. Now this sort of maybe have to
rethink my entire world. I didn't realize that this this existed.
I mean, I've heard of people having extra nipples before,
but I thought that's weird. How does that happen? And
I didn't realize before I read the stuff about the
milk line that that's why. So it's not uncommon for
(04:41):
hints of nipples pat nipples passed to hang around disguised
as a freckle or a mole um. They're called super
numerary nipples. Did I did? I pronounced that supernume a
lot of um. And yeah, you might just think that
you have a really big mole on your boob area
(05:02):
or your chest, abdomen wherever it could be. It could
be a spare nipple, yeah, because that's why I I
do know someone with an extra yeah, but with a
tiny I mean, you can barely tell that they're they're nipples. Um,
and they're directly below where um, you know, his actual
(05:23):
nipples are. And uh yeah, I always thought that it
was an extra growth, but no, it just means that they,
you know, they had an overly developed milk ridge line,
which is why you wouldn't have one, you know, probably
hanging out right on top of your belly button there,
you know, it would be more in parallel line. But
(05:43):
typically mammals. Fun fact also about nipples is that usually
mammal mammalian nipples come in even numbers. Oh yeah, I
think so. We have two arms, two legs most of us.
There is one possem and I forget which which exact
type of possumatists that comes with thirteen nipples all in
a in a nice story. Oh yeah, there's one right
(06:04):
in the middle, like a baker's, doesn't you know. Yeah, Well,
anyway back to people. Um, the American Journal of Primatology,
well okay, well this is primatology. They were talking about monkeys,
but they talked about humans too, And in the American
Journal of Primatology in two thousand they said, uh, most
(06:24):
supernumerary nipples result from a failure to terminate mammary bud development.
So you know, it's not like they're hurting you, just
that you know, your body was like, I've got other
things to do. And it's linked to what it's something
called the hawks is gene It's all about gene expression.
And you know how how fully it uh, you know,
the genes will express themselves and either stop the the
(06:47):
milk ridge development or keep it going too long. Yeah,
the hawks genes set up the head to tail organization.
And the reason why supernumerary nipples are relevant in this
discussion of male nipple I want to say nippleage male. Uh.
The reason why it's relevant is because, according to the
(07:09):
European Journal Pediatrics, there is a higher prevalence of supernumerary
nipples on the left side of the body and in men. Yeah,
so you should be running to a mirror right now.
Those those freckles, You've got freckles on your abdomen. I'm
just saying it could be could be an extra set
from the the old milk line. Right. Um. Now, kind
(07:33):
of back to more of why men have nipples in
the first place. Um, Basically, there's this talk of genetic correlation.
The idea of two traits shared genetic basis right, because
going back to our conversation about UM, the chromosomes we have,
you know, women developed breasts because of that, you know
(07:56):
that twenty three pair of chromosomes, the double X. That
UM is linked to sexually dimorphic traits, which are basically,
you know, the obvious physical traits. You know, men grow up,
you know, developing penises, women developing v China's things like
that that separate UM males and females. But nipples are
(08:18):
not one of those things. It's a genetic correlation. And basically,
in order for men to from an evolutionary standpoint, for
men to not have nipples, it would have to be
um more beneficial for them reproductive ones to not have them, right,
it would have to be doing some damage or hurting
(08:39):
them in some way, or be more um evolutionarily advantageous.
There we go to not have them. And since basically
essentially it doesn't matter if men have nipples. So but
since it's a traite, a genetic trait that men and
women share, and it's so important for women to have nipples,
then it would almost be too much work for us
(09:01):
too for men to evolve losing nipples. Right, So it's
more that there is a lack of selection against them
rather than a specific selection for them. Right. And explaining
all of this to Scientific American, a mamalogist named Douglas
Long says, it's a lot more difficult to lose an
organ than to develop an organ. And he compared it
(09:24):
to the reason why we have to nails, like, we
don't necessarily need toenails at all to claw and dig trees.
You know, at least we have something to paint. Yes, exactly,
who doesn't need red fingernails for whatever reason? Um? He Actually,
Douglas Long did say something that I thought was funny
when I did more reading. He said, not one male
(09:45):
mammal has been shown to lactate, And then everything else
I read was like, oh, well, yeah, we've got these bats, yeah,
and goats and things. Um. Jared Diamond, he's an author
and physiologist. He pointed out in a nineteen any five
article for Discover magazine that the Dyak fruit bat in
Southeast Asia can spontaneously lactate, and that is one of
(10:08):
the only examples of a male mammal that has been
seen to lactate, just under no sort of laboratory um
conditions at all. Because there have been male goats and
I believe male cows that have lactated, but that's because
they were induced with hormone that's stimulated lactation. And one
(10:33):
one fun nipple fact stallions male horses they don't have
nipples at all. They don't neither do platypuses. Yeah, the platypus,
they were so gross. Oh I thought it was kind
of cool. Still Okay, it talks about how they don't
have nipples. They just sort of like leech milk. Yeah,
the milk just comes out of their pores and then
(10:54):
their little baby platypus puses look it up. They don't
like it, take it away. Um, okay, well back to again,
back to people, all right. So Jared Diamond in his
article also discussed actual male human lactation. Um, it's sort
(11:15):
of It can occur when the pituitary gland gets all upset,
and that can happen when you face starvation. And so
he pointed to survivors of Nazi concentration camps and Japanese
prisoner of war camps who had been starving and when
they got out, they experienced lactation when they began to recover, right,
(11:35):
And that's because the pituitary gland in the brain stimulates
the production of a hormone called prolactin. And when we
produced prolactin, it triggers alveoli in breast tissue to produce milk.
And the reason why those concentration camp prisoners in the
prisoners of war experienced spontaneous lactation was because when your
(12:00):
body recovers from starvation, your glands recover a lot faster
than your liver, which absorbs hormones. So basically they have
the spike in prolactin and lactation which can also happen
in newborn's right. Yeah, this is called witches milk. And
it's when you know the baby is first born, it's
(12:23):
still has a lot of its mother's estrogen pumping through it,
and so it can just spontaneously lactate when it's born,
and this can continue for a weaker So yeah, because
and that's just when you're pregnant, prolactin levels surged ten
times higher than normal and that can seep into the
placenta and you might give birth to a lactating baby. Yeah,
(12:45):
I'm just gonna adopt dogs. Um, but it's not just
pregnancy or starvation that can cause men to spontaneously lactate.
Diamond theorizes that some combination of manual nipple stimulation and
hormone injections may develop a father's latent potential to make milk.
And in Scientific American they touched on this issue in
(13:08):
again in two thousand seven, UH and they pointed out
that medical anthropologists Dana Raphael an into chronologist Robert Greenblatt
agreed that men couldn'tduce flactation by stimulating their nipples. So
I am never giving another titty twister to anyone. Well,
and that's because when um, you know, when when a
baby latches on to a nipple, it stimulates sees mechana
(13:33):
receptors in the brain that gets the whole pituitary glamb prolactin.
I'll be only process going. But that does not necessarily
mean that you know, if you were if you were
to give um, if you were to give a man
a baby and the baby was yes, and the bay
were to latch onto that male nipple, because it does
(13:53):
happen sometimes. Um, you know, babies just they see a
nipple and they will latch on if they're hungry. But
that doesn't necessarily mean that all of a sudden, you know,
the faucets will will turn on and and a mail
will just spontaneously lactate. It definitely takes um, takes a
little bit of time. There was one study, this was
(14:14):
out of Canada. They were looking at adoptive mothers who
had adopted infants and whether or not they could sort
of stimulate uh, lactation through using breast pumps over time
and um contact with the infant to get their bodies
producing the prolactin. And they were able to stimulate it
in about I think it was thirty of the mothers.
(14:36):
But it kind of just goes to show that a,
you know, women already have you and I have, even
with though we're not pregnant, have a third more prolactin
running through our bodies. Uh so we already have a
head start over men. And even with that, it's still
hard to to just automatically jump start lactation, right. Dr
(14:56):
Jack Newman, who's a breastfeeding expert, says, basically, know hormone
spy cast you occur in order to produce milk, and
that brings us back to the pituitary gland which we
said secretes prolactin, and he actually Dr Newman points out that, hey,
it could be a pituitary tumor just while you're while
you're lactating um. But there's a lot of other stuff.
(15:17):
There's medications like thorazine, which was a popular antipsychotic in
the mid twentieth century, which affected the pituitary gland and
cause a spike in prolactin production, and certain issues like
testosterone deficiencies with male hypogonadism can cause a condition called galactia,
which is basically spontaneous lactation like we keep um talking about.
(15:41):
And if you're curious as to whether or not the
milk that men can produce is similar to the milk
that women produce, as a matter of fact, in nine
study conducted at the University of Western Australia confirms, but
yes it is. It had very similar contents to um
female levels of protein, lactose, and electrolytes in this in
(16:04):
this man's milk. It's usually just it's not so much
the content of the milk but the volume. Even when
men do lactate, they're not you know, they're not filling
up baby bottles. A writer from Slate actually did a
little experiment. He wrote about his journey into male actation.
He bought a breast pump manual not I don't know, motorized,
(16:26):
the electric little lact ones I don't know, and m
he you know, he just didn't have any success and
he gave up. He I don't think he liked the
idea of having to pump his body full of furmans
and take a three hour three hour breaks. And right
he was like, I can either take these these medications
that will you know, mess with my pituitary grooland and
(16:47):
possibly made me kind of crazy and lactate. And he
tried to take um finn a Greek which is this
uh like a herbal supplement. You can get it um
any natural food store that's supposed to do a similar thing,
like a lot of um, you know, like maybe like
neonatal uh. Herbal supplements will contain Finn agreed to help
stimulate lactation. And he was taking it like three times
(17:10):
a day, drinking fun of Greek tea and yeah, nothing,
nothing happened. And he determined that maybe it was the
fact that he didn't have an infant. I mean, he's
a single guy and he didn't have any any little
life depending on him and his like patition, and it
was interesting, like um. Charles Darwin, not not too surprisingly,
(17:32):
was fascinated by this this uh this whole male nipple conundrum,
and in the Descent of Man he posited that men
used to evolutionary or evolutionary ancestors. Men and women used
to uh suckle our young and it was only once
our litters got smaller to where it could be managed
(17:54):
at breastfeeding could be managed by just one of the
caregivers than men gradually stopped breastfeeding. But we still just have,
you know, they still just have the remnants because like
I said, it's not um. Male nipples are not vestigial
because they do contain um, breast tissue, the blood, vessels, nerves, alveoli.
(18:16):
They can you know, men can lactate, yes, and they
do and they do in Central Africa, the the Aca tribe.
I think that's a prous it um. The Guardian and
two thousand five reported on American anthropologist Barry Hewlett who
lived with this tribe and studied them, and he discovered
that the men nurse their infants when the mothers are
(18:39):
you know, away doing whatever. And part of this is
their whole culture is so fascinating to to us as
Westerners because all of their roles are completely fluid. They
have no problem trading off cooking, hunting, caring, caring for
the babies. He even pointed out, um that the men
would you know, strap the babies to their sides and
go down to the equivalent, but the tribal equivalent of
(19:01):
the bar, and hang out with their buddies with the baby.
It wasn't you know, it wasn't weird because they don't
view children as burdens something to you know, waste resources
or whatever, take up resources. I guess I should say, um,
they look at children as a blessing and so everybody
wants to pitch in and take care of the babies,
(19:23):
including the dads who have been known to la date. Well.
It's also interesting because you know, the women are away
from the household because they're seen as just as adequate
hunters and gatherers, you know, in this in this culture
as the men are. And according to the anthropologists, he
said that men are with their infants forty seven percent
(19:43):
of the time, which he by his calculations, was basically
the most dedicated fatherhood of any culture on the planet. Um.
Which is kind of fascinating that that these men would
um possibly be lack hating more than say, fathers in America,
which don't spend as much time with their children. So UM,
(20:06):
so buck up, guys, just if if you spend a
little more time with your family, maybe you too could
breast face Well, I mean, it's just it's a It's
an interesting example because Jared Diamond, who wrote that Discover
magazine article that you were talking about earlier, uh, says
that the evolutionary conditions that would favor male lactation would include, UM,
a litter of infants that constitute a big burden to nourish,
(20:29):
so you know, you would need um more more hands
on deck, monogamous male and female pairers, high confidence of
males in their paternity, and hormone preparation of fathers for
eventual lactation while their mate is still pregnant. They expect
to do that. And it sounds like to some degree
maybe this pygmy group in Central Africa, UM, I don't know,
(20:51):
maybe perhaps those those conditions are more ripe in the
less gender segregated society. They don't see it as weird.
If the women can do what the men can do
it and vice versa. Yeah, and because guys, have you
got the equipment and you might actually have more nipples
than we do on the left side of your body.
I'm so glad I know about milk ridges now to
(21:12):
not really though I don't really I didn't want I
didn't really want to know it. What fascinating nipples. Anyway,
with that, Carolina is going to have to go through
a little bit of a therapy from all of this
male lactation research. Um. And of course now we would
like specifically letters from men who pops possibly lactated. Is
(21:37):
there anyone out my gosh that would be okay, that
would be fascinated actually to actually hear from one of
you guys. I mean it's like especially fathers out there,
who have you know, dealt with because it seems like
this issue is a lot more pertinent for for dads
who have wondered like, well could I, you know, could
I help my milady out and with the breastfeeding duties?
Well you maybe maybe maybe let's not talk to some
(21:59):
the AKA people in Central Central Africa maybe have some
tips and in the meantime, you can email us at
Mom's stuff at how stuff works dot com. And we
got a couple of emails to read right now. So
I have an email here from Marie in our in
response for episode on women in science. She says, I'm
(22:20):
a third year grad student in microbiology immunology research, and
I'm wondering about the cultural influence on women in the workplace.
A huge proportion of research labs, at least in the biomedfield,
is international. Many of them are women. We have a
Japanese female post doc and a Chinese female research associate,
but I haven't exactly counted the proportion. Are there other
(22:41):
countries that still discourage women in science? In my own experience,
I've never felt at all any discouragement to go into
sciences because of being a woman. On the contrary, many
of my science teachers were women. I hear all this
talk about gender bias, but I've never seen it in action.
Of course, the biomedical sciences are different from other fields.
I've read somewhere that it's engineering and compute your sciences
that are the most skewed, And yes, she is right.
(23:03):
Engineering has ze lowest proportion of female students least in
higher education. So thank you for your input. Marie and
I have an email from Lorian. This is in response
to our pregnancy test podcast and my enthusiasm for the
self exam. The pelvic self excuse yeah um, she said.
(23:26):
There is a birth control method called the Fertility Awareness
Method or FAM, which uses basil, body temperature, cervical fluid,
and the position and openness of your service to chart
when you're ovulating. It's very easy once you learn, and
takes really only seconds a day to take your temperature,
note what your cervical fluid is doing, or to check
your service. If you're trying to conceive, you can concentrate
(23:49):
your efforts, and if you're trying to avoid pregnancy, you
can avoid the fertile window. There is a wonderful book
called Taking Charge of Your Fertility that talks about it
in detail. I didn't do a pelvic selfing ZAMBA because
I was charting my cycle. I was able to get
my first positive test nine days after ovulation, which was
quite early. My midwife was so confident in my days
after seeing my chart, we opted not to do an
(24:11):
early dating ultrasound. It's really a neat method and has
empowered me and knowledge of my body utili awareness. I
need to look more into that. Uh. And of course
our email is mom Stuff at how stuff works dot
com and you can find us over on Facebook, follow
us on Twitter at mom Stuff Podcast, and check out
our blog during the week, It's stuff Mom Never told
(24:33):
You from how Stuff Works dot com. Be sure to
check out our new video podcast, Stuff from the Future.
Join how Stuff Work staff as we explore the most
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(24:58):
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