Live Like a Girl with Dr. Mindy Pelz - Menopause's Role in Human Evolution: The Grandmother Hypothesis with Kristen Hawkes

Episode Date: February 3, 2025

Kristen Hawkes' "Grandmother Hypothesis" provides a fascinating perspective on human evolution, menopause, and the unique social structures of humans. This theory posits that the long post-reproductive lifespan of women evolved because grandmothers played a critical role in supporting their descendants. By helping care for grandchildren and providing resources like food, grandmothers enhanced the survival and reproductive success of their families, which indirectly passed on their genes favouring longevity and cooperative behaviour. These contributions are thought to have driven distinct human traits, including increased brain size and social complexity, by encouraging intergenerational support and skill-sharing To view full show notes, more information on our guests, resources mentioned in the episode, discount codes, transcripts, and more, visit https://drmindypelz.com/ep273 Kristen Hawkes PhD MS BA examines foraging and social strategies among hunter-gatherers to shed light on human evolution. Her work includes three projects focused on life history evolution, aging in captive chimpanzees, and understanding fire's effects on foraging payoffs, all informed by ethnographic studies of the Ache in Paraguay and the Hadza in Tanzania. Observations suggest that men's hunting primarily serves status competition rather than provisioning, while grandmothers play a crucial role in supporting their grandchildren, especially when mothers have more children. This aligns with the grandmother hypothesis, which explains human longevity and highlights differences between humans and chimpanzees, such as longer lifespans despite similar fertility rates and a male-biased sex ratio. Mathematical modeling underscores the impact of grandmothering on post-menopausal longevity, shorter birth intervals, and social behavior. Kristen Hawkes continues to collaborate on data collection and analysis to enhance understanding of ancestral foraging strategies and aging in captive chimpanzees. Check out our fasting membership at resetacademy.drmindypelz.com. Please note our medical disclaimer.

On this episode of The Resetter podcast, we dive into the grandmother hypothesis with the queen anthropologist herself, Kristen Hawks. Now, if you've been listening to me for a while, I have been obsessed on this hypothesis. It was first brought to my attention by Lisa Moscone back in the spring of 2024 when I interviewed her here. And what I've learned since then of studying the grandmother hypothesis is that there is that there is an evolutionary reason why female humans live so long in our post-reproductive years. The grandmother hypothesis says that the purpose of the grandmother was multifaceted, but the biggest

piece is that we were necessary. We are necessary for the survival of our species. We forged for food. We took care of the young back in the primal days. And that, there was a purpose to us living so long in these reproductive years. And Kristen is going to talk about that here. What's exciting about bringing you Kristen Hawks is that she has actually spent a majority of her career, not just understanding this hypothesis, but also witnessing it in the Hadza tribe. So the Hadza tribe is a tribe in Tanzania that displays this grandmother hypothesis in action. And so I got to ask her firsthand, like, tell me what you saw because she witnessed these beautiful, this beautiful tribe.

What did you see there as far as the hierarchy of men versus women? And what did you see about the necessity of women, of the grandmother and the post-reproductive woman in the survival of the tribe itself? So I'm getting it directly from the resource who has witnessed this, which should be hopefully enlightening to you all. I loved this conversation. I also, at the end of it, was really interesting because when you dive into the grandmother hypothesis, you hear a lot about the only other mammal that lives as long as we live are orca whales. And she talks a little bit about what she understands around the grandmother in an orca whale pod mixed with what she saw in the

the Hads of tribes. So this is a deep conversation. It is all built around evolutionary biology. But most importantly, why I wanted to bring Kristen to you is that nothing that the human body does is by mistake. Everything we are experiencing, whether it's through our bodies or mind, has some kind of primal connection. And when we look at menopause, the reason that we live so long is because we can take the energy we were using for reproduction, and now we can use it for other parts of our life. Specifically, we use it for fitness, we use it for cognition, and we use it for social development, as you will hear in this episode. So I'm so excited that we hunted Kristen down. I'm so excited to bring this conversation,

to you. It is deep. It is definitely one that is through the lens of an anthropologist, but most importantly, if you're a postmenopausal woman, what I want you to know is that the back half of your life has an evolutionary explanation, and Kristen is about to bring it to you. So Kristen Hawks, hope you enjoy it as much as I loved talking with her. Welcome to the Resetter podcast. Welcome to the Resetter This podcast is all about empowering you to believe in yourself again. If you have a passion for learning, if you're looking to be in control of your health and take your power back, this is the podcast for you. So let's start here. Just, you know, for my audience, can you explain what the grandmother hypothesis is so we can get everybody up to speed on that?

my temptation is to say that the usual textbook story of us is the hunting paternal provisioning hypothesis, that what happened with these climate swings that actually started in the myocene and these very dry periods and then these swings in ancient Africa were breaking up the forest and that had effects on the plants that were doing well and the animals that were doing well. So there was all kinds of response to this. And a population that's ancestral both to us and to genus Pan. So that's chimpanzees and bonobos. Some of those guys who then became our ancestors were drawn into the resources outside the forest.

Now, in the forest where chimpanzees still live today, and same way with gorillas, same way with orangutans, all the great apes, the babies can already feed themselves while they're nursing. Mom is carrying them along. She's feeding herself. They are starting to feed themselves within their first year. And we now have quantitative data showing the number of foraging bouts of these chimpanzee infants. by the time they reach their first birthday is essentially the same that they'll continue until they're weaned, and then mom will have another baby and they're entirely independent feeders.

But the population that was drawn to these other resources, there were pay-off foods that gave you a really high return if you were big enough, but the little wouldn't do it. And that is what's set up. I mean, there could have been a lot of extinctions around Tristan. But you are mom and here is the infant. Then if it can't feed itself, then that is a problem for you. It will mean, oh, whoa, I can't have another one yet because I need to subsidize this one. But because the subsidies are not milk, it can be somebody else. And the older females whose fertility was ending, they're still big.

Their return rates are high. And we actually have data from these wonderful old hathsha grandmothers who are right. Oh, ladies and their return rights are the same. Still, they are big enough and strong enough with these foods. And that means that their productivity, their economically, productivity and subsidize the fertility of the childbearing ages still. And so that means these two things then get favored by selection. Increased longevity, postmenopausal longevity, and shorter birth intervals.

And those two things co-evolved down the generations. And because we hung our grandmother hypothesis on these models trying to explain, the broad variation in mammal life histories, you know, you think mouse and elephant, there's so much variation, you know, the ones that take a long time to grow up and are big and then they live a long time and have babies at a slow rate like elephants. And then the ones that, boy, they really go fast and they have as many babies as they can because they're going to die. Well, I was so influenced by a theoretical biologist who had built models to explain that variation. And actually, our life history seems so, wait a minute, if you look at the relationship

between adult mortality and age at maturity, which would be first birth, and when we're talking about this ape, when we're talking about people, humans, yeah, humans who are foraging for a living. So the mortality regime is different than the one. we live under, you know, no scientific medicine, no public health. Right. What is the case is that the relationship between adult mortality and age at maturity in us is right where it ought to be in that model. And that was puzzling because in the model, through adulthood,

females are continuing to produce offspring. Well, wait a minute. How can we fit that model? And yet, childbearing ends in us. And now we have these data showing it's the same thing in chimpanzees. If they live long enough, before 50, fertility is over. They're going through menopause two. That is an ancestral condition.

But they're aging way faster. And they don't usually make it to those ages. Right. Yes, right. And what happened in us was, there was a fitness payoff for aging more slowly because by subsidizing those grandchildren, you ended up having way more descendants. And that's how natural so it works, right? And so seeing that this model, Eric Chanoff's mammal model, that wait a minute, we fit for that,

it ought to mean, if we're right, then we would not fit for the other invariant, as he called it. We ought to weigh higher rates of baby production. And that's exactly the case when we have the demographic data to show it. And so there we were with an explanation, but it was only the females. And it was then by beginning to recognize and take on board, this is such an important part of the story. All of us, and this is true for sexual reproducers generally, all sexually reproducing things, including plants, if they're sexual reproducers, right? And including chrymaphrodites, there are all kinds of cool organisms that do things really differently, but are sexual reproducers, And if so, then everybody has one mother and one father, and they get half their genes from mom, half from dad.

And every one of us and every individual in sexually reproducing taxa, it takes one haploid sex cell, joining with another haploid sex cell to produce that cell, that zygote, that's the beginning of a new end. individual. So half of it comes from dad, half of it comes from mom. That's labeled in general in evolutionary biology, the Fisher condition that has all these consequences because it means half the genes in future generations come through males, half comes through females. And selection is working on everybody. And the various compromises that ensue from that are fascinating. And so once and this was well you know I again it's hard for me not to tell the long story of how right right no you've been deep in the work let me let me just say one thing in what I because I've listened to

thousands of your podcasts I've been studying your work and what I what I just heard in what you just said is that we have been so closely compared to chimpanzees and that where we start to see that we vary from chimpanzees is when we look at menopause. And part of how I even got to your work is I kept asking myself, what's the purpose of menopause? There's a reason we live 42% of our life post-reproductive. Exactly. And every person I asked that to, nobody could give me an answer until I found your work. And what I'm hearing and what you just said is chimpanzees, the young, are able to feed themselves very quickly. And post-reproductive, my understanding from your work is chimpanzees die within like three years

or more after they're reproductive. But that doesn't happen to us because the grandmother is so important for the survival of the species that we had to go 42.5% of our life post-reproductive because it was the grandmother that has kept our species alive. and that separates us from our chimpanzee friends. Right. Is that right? Lots of it is.

I mean, somebody like me is going to say, survival of the species is not the way to try to think about things because selection is all about competition within the species, right? Ah, yeah, okay. Which ones do better, and that's what changes things over time. You know, I mean, Darwin, it's amazing what he saw when he had so few tools. and, you know, astonishing. That's cool.

I mentioned R.A. Fisher. So the combination of Mendelian inheritance and natural selection, it just gave us all these incredible tools to explain what's going on. But what Jane Goodall did when she was really getting to know those chimpanzees at Gombe, she said, I'd put the beginning of old age at about 33 because what she saw, was that the rate of aging was faster in these chimpanzees than it is in us. So it's not as the females live to the end of their fertility and then they die. No, they are dying at a higher rate. So it's actually very few of them who live through the end of their fertility, very few who live to and through

menopause. But now we have these really cool data from this chimpanzee study site in Uganda and Gogo, where a few females are still alive and therefore the hormonal signature of menopause in these females looks just like this eight. Like us. Wow. We had, we thought that was the case from the data that we could pull together. And now it's really been confirmed. Now we're starting to see a little different. So one of the things. So one of the things. I've seen in your work, and I also have gone back and looked at, you know, Margaret Mead and like her menopausal postmenopausal zest is that what I think is not being highlighted enough, I feel like the conversation around menopause has been, you know, that we slow down. But when I look at the

grandmother hypothesis and I look at Margaret Mead's postmenopausal zest, there's a redistribution of energy that actually gets used for our good. And my understanding, correct me if I'm wrong, is that it falls into three categories, which is fitness, cognition, and social. So what is it that we are getting, so as women, when we're not putting that energy towards reproduction, that energy goes to another resource.

Can you talk a little bit about that? Well, you know, again, the way I would teach this and try to explain to people who haven't obsessed about this as long as I have, is that what light histories in general are all about is these allocation tradeoffs. You know, how much goes into this thing, because more going into that means there's less into this other thing. And so that division between somatic maintenance, repair, and growth. So building this organism, then keeping it repaired,

and maintained, that takes the allocation of whatever is available, has to go, if, well, how much goes there, trades off against how much goes into what's called current reproduction. And so the tradeoffs there, well, first of all, it's going to determine whether you should continue to grow bigger before you mature. And then I can say, well, I selection would favor that. Sometimes it depends on adult mortality. I mean, those are the best models we have. But what is the case that the more that the future pays off in fitness, the more there's an advantage to be around to get the payoff. And that means direction favors slower aging, more into somatic maintenance and repair and less into current reproduction. And that's the history.

of our somatic versus current reproductive allocation. So more goes into, well, first making us bigger, we're bigger. Yeah. Before we stop growing and mature. And then actually, we put less into current reproduction. Others are contributing. Grandmother is right. Right.

And so I put less. as a mom and move on to have another. And so all kinds of things follow from that as well. And I, you know, this is why I keep saying, how did it take me so long to see how these other pieces of what characterizes us are connected to exactly that suite of changes in life history? Because it's not only, because we get half our genes from males, half from females. And so this in slower aging applies not only to females, but to males as well.

And we're mammals. And so in mammals generally, not just in us, females get all of the cells that are going to turn into OVA very early in life. This finite seed. And then it just depletes, you know, cell death as we go on. Right. But, you know, apparently we lose. half of them before we're born in us. Yes, I've heard that, yes.

Keep losing them before we start to menstruate, continue to lose them. If we're pregnant and lactating, we're still losing them anyway. That is continuing to go on until if you live long enough, then you no longer cycle because you're not getting the suite of hormonal changes that would run a cycle. Right. But in mammal males, they continue. to produce new sperm through adulthood. And that has these huge consequences

that with the increasing fraction of post-menopausal females, there are also all these old males who are still fertile and therefore competing with the younger guys for patronities, and the only place they're going to get them, is where there are going to be,

babies, right? So. Right. Yes. There is crucial in two ways. One is then you have way more males competing and that has consequences for the strategies of a male mating competition, which all kinds of, I mean, you can see this across the living world in birds. It's so visible.

But anyway, all the modeling that shows when you have this male bias. sex ratio in the fertile ages, then the strategy that wins for males is to claim a female and defend her against the other males. And that is a way in which we can account for this pairing habit that characterizes us and distinguishes us from the other living shapes, from chimpanzees and bonobos and so on, right? So we, they do not do that. It is something you see in human populations everywhere. And then the age structure of that, the old guys competing with the young guys. So the old guys who are ahead in developing their reputations and so on, then they dominate the young guys. So we get all of

these features that are characterized recurrent features, the patriarchy recurrent features are I was just going to say, like, the more I listen to you, the more I'm like, and the wise, I believe that it's the wise female elder that it needs to be the hero of the culture right now. Because what I just heard is that even when men age, they're still because of their reproductive status, they don't have this major shift that women get. And so it, and if you tie, I don't know if you've ever heard Lisa Mascone, but Lisa Mascone is a neuroscientist that says that when we go through menopause and we lose estrogen, that the brain reorganizes itself, that the neurons that we needed to keep ourselves in people pleasing

and keep ourselves looking, you know, attractive to the culture get pruned away. and new neurons come online that give us more of a social lens. And when I look at her research with your research, I'm like, wait a second, hello, the menopausal woman is the evolutionary heroine here. She, instead of tossing us aside, people should be embracing us because of if you just looked at our design, we are incredibly needed for the culture. So that's how I see what you just said is that we are in a category as postmenopausal women. We are in a category of our own because of this evolutionary design that we are built upon.

We are. We are in a category of our own, but it is the case in sociocracies like ours, the tendency that, oh, wait a minute, I don't want my gray hair to show. Right. All of that kind of thing that goes with living in a socio-ecology where youth is absolutely considered to be so important. Yes. And especially when it comes to females. And so all of the things that characterize this tendency to want to still be considered sexually attractive, all of those things. all of those things are a part of the socio-ecology we live in and the life history that has characterized this animal.

And it is the reason that we have, well, all kinds of both pros and cons. Because one of the things that goes with this, not only the male strategies, which initially I did not, I mean, I thought these were two interests of mine. What's going on with male strategies and the life history stuff? And I thought separate lines of research. And boy, in the last few years I've seen, no, those things are so connected. We're in a category of our own. Yeah. Well, but the two things are so linked to the grandmother hypothesis can't explain what the boys are up to.

Yeah. And the other thing I mentioned, this is a different angle on brains, but that's the, thing that goes with our slower development is also this slower neurogenesis, which results in the much bigger brain. But here are babies in our radiation that are maturing more slowly. So as I was saying, these chimpanzee babies are already, before they're one, they can do all this stuff. And where one-year-old, you know, human babies, I'm just a baby. but because the life history shift includes this earlier weaning, and that's so crucial to why the slower aging and the post-manipausal longevity was favored,

because there were then more grandchildren and therefore more copies in the future, the babies who are developing so slowly and now mom is having a, another one, and yet I am not able to even come close to think about feeding myself. And therefore, and this is where Sarah Hurdy had laid this in front of us almost a quarter of a century ago, and yet making this connection. And I have been so influenced by her in so many ways, but connecting these pieces, you know, it's still, why did it take so long? But so selection on babies to make the social relationship more important than anything.

And the thing about human babies is this social precociousness, smiling, trying to, you know, somebody. Am I not so? Yeah. That is the mirror. And the mirror neurons, like, yeah, there is definitely a draw to the adults around you as a human baby. Absolutely. And trying somebody, be sure to invest in me. Mom, what about me? Yeah. Stuff, which is not going on in the other apes. That's not an issue.

Right. Interesting. Was how selection on that social engagement, the importance of it, that it's a survival was a survival strategy in these ancestral populations. for babies. And as a consequence, selection for all this social stuff when motorically everything is so slow. And that results in this early wiring of our brains to make the social relationships take priority of it and end up with what I are doing right here. So there's apatom. Or, can we connect? Can you see what I'm talking about? Yeah. You get what I'm, when you're doing, same to me. That's close with this life history. That started, yeah. So, okay, so go back, if we go back to, I call it cave life, go back to the primal days, when the hunters went off,

it was it mostly the men that went or was it older, you know, teenage girls, like, or was it primarily the men that went off to make the big animal kill? It's, it's primarily the men. And one of the things. So when I first was doing ethnography with people who know how to do that, who forage for a living, but that was the story of us, the hunting hypothesis, a paternal provisioning hypothesis, famously brilliantly synthesizing what everybody thought they knew in the last century about both foraging, you know, people who were foraging for a living and the other apes. And this story that, Well, if you look in other primates, you see mom and infant, and it might have a social relationship with the older one.

And then what happens in us is dad is there to bring home the bacon and to subsidize his wife and kids. And that explanation for nuclear families was it still in the textbooks. But the data so clearly show that is not what happens. And our research has provided this quantitative data showing that, boy, when you go for those big animals, if you're successful, it is a bonanza. Everybody is so excited about it. We'll take advantage of it. But you fail almost every day.

So when you're successful, it's huge. but if the kids have to eat every day, that is not going to do it. And what turns out to be crucial? And our, again, our Hotsah data quantitatively showing this. And James Woodburn, who had started as an ethnographer with these foragers in northern Tanzania, these hodzah folks in the 50s, he had actually written about all this and talked about how well, the women and children go off and feed themselves. And then the men, they go off individually and get plant foods to feed themselves.

And then they really go to work. And then they are competing with each other to show that they can get these big animals. And everybody knows who the really good hunters are. And the guys who are the really good hunters, well, nobody wants to cross them. They want to make sure that they are somebody who would be an ally. And so all of these reputation things that are hugely important for the males that have consequences for whether or not they can make this claim on a female. And the other guys will say, okay, I see.

You got, you know, right, I'm back. Right. Oh, they're like a cave hero now. They're like, I came back with the kill. I get to feed, and I get the woman, I get the fertile woman. And my, my, I'm collaborator on this project, Nick Lurton Jones, whose demography, you know, it takes so long because to really get the numbers on these things. Right.

But now we have those data showing that the guys who have reputations as, as better hunters, they end up with, well, first of all, when their, when their current wife, is her fertility is ending, well, then, you know, they get another one. And then the tendency is for the guys who are better hunters to spend more of their life sleeping with a woman, right? Right. Being married. And they end up more surviving descendants, not because their kids eat better, but because they have more kids. So all of them come together. Interesting. Stamography, showing that the survival, so Nick, now we had the weights data showing that, well, first of all, these old ladies who were so amazing and seeing their return rates for this very energetically expensive thing of digging these U.S.Os was essentially the same as the younger women.

But they spent more time at that. And so then we could see, because people let us weigh them. I mean, they were wonderful. And so we were waiting. This is the Hadza. This is the Hadza tribe you're talking about. That's right. And we were weighing. I wish we'd done it more often. But anyway, we were doing that. And people were, you know, letting us do that. And so then we could actually see that how well the kids were growing. So this is, remember the other apes where they're already feeding themselves. Well, the little kids are trying, but they're too little. And it turns out that the growth rates of the little kids was core. related with how much their mother worked until she had a new baby. And then that disappeared and it was grandma.

And so that very tradeoff between what the subsidies coming from the older females meant for having another baby sooner because then the older one is not completely left in the lurch, right? now that kid will be subsidized. So all of these things that shifted in the life history go with that adjustment to depending on foods that the little kids can't get. And the standard story is it's all about hunting the big animals. Well, hunting the animals is important, but it is not what feeds of the kids. Yes, right. What the women are doing. And Woodburn had described this in 50s. And yet, you know,

you know, still that hunting paternal provisioning hypothesis. It's still the one that continues to be favored. Let me tell you a couple of interesting conversations I've had that back up your hypothesis in different ways. So what I hear you saying, and this is what I've, that supposedly what three percent of the time the men came back with some kind of big animal kill, which meant that somebody else had to be giving, providing food for the mom who's pregnant and the little kids. And that was the grandmother. And then the grandmother, what she was able to gather was tubers and plants that she

could pull out of the ground to bring it back to feed the mom and the kids and probably feed the male hunters when they didn't come back with a kill. So she was providing sustenance for the tribe because the big kill wasn't happening all the time. So let's start with that. Is that accurate that it was the grandmother that was keeping everybody alive? What our data show, and again, this is what Woodburn also described to the hansa, is actually the women and kids, including pregnant women and little kids, they go off together. But it is the way in which the productivity of these resources means they're getting a high return rate. And they eat. at the site where they get it, and they actually end up bringing,

as the Woodburn's language was, after they've fulfilled their hunger, if there's any left, then they bring it back to camp. But not to feed the men, it is just as likely to be eaten by the women and kids. And the men go off individually, periodically, and they know how to dig tubers. They were little kids.

and they are feeding themselves on these other reliable plant resources, and as Woodburn said, and our data showed this too, that when a guy goes off to supposedly go for a big animal, that's his real target. But if he happens to kill a small animal, he's very likely to cook it and eat it right there and not take it. Right there. He doesn't share it. Right. So what is it, what is it about the grandmother then in this because it's her brain, her ability, because she doesn't have all the energy going to reproduction, that she becomes pivotal in this food foraging system

that was a make or break moment for our evolutionary or what I call our primal friends. So what was it about her that was so pivotal to nourishing? Like what is it in her that allows her to have that extra zest to be able to find food for the tribe. Well, you might find other people who will have ideas about that. The way I think of this, and, you know, again, the women I was watching do all this, is this is what you do sort of, wow, starting.

I mean, it was the, what would we call these girls who haven't had a baby yet? And they're actually there, but they're, you know, beginning. to cycle maybe, but actually age at first birth in these faraging populations is about 19. You know, it's not, we don't have. And it's not because they're not having sex. Right. When they are ovulating and they are, chances are they'll get pregnant. But it's girls in those nubile ages who actually, their rates are lower and it seems

to be that they're paying less attention to the work. And often they're holding the baby. You're off in there. If a woman is distracted. Persing a baby, you know, then she'll have the baby. And she doesn't stop foraging, but she's not getting as much. And that is associated with how her ween kids are not then, depending on her. It is the work of the grandmothers.

But here is the picture, you know, from my experience, which is that the women are together and this kind of food is one in which you don't have the feeding competition that can happen with transies where females actually try to stay away from other females because, you know, somebody else who's trying to eat the same soft fruits and leaves is competing. Right. But when you are going for things like these U.S.Os, then actually digging next to somebody can raise your rates because you start and you're just, you know, you have a digging stick and you're just, Yeah.

...being there until actually gotten into, started to dig a hole. And because of the way these plants grow, you have a whole bunch of tubers, you know, like potatoes. So somebody digging right next to you means your rate, you know, it's the sigmoidal thing where initially it's low. And then it can really go up and it can go up faster if you and somebody else are digging next to each other. and the way in which things went on when we were, you know, people were so wonderful, timing everything and weighing everything, was that you would, you dig a batch and then look it together and everybody eats there. Together. Yeah. Everybody's there.

And the little kids are there and they're taking advantage of the fact that there is this pile of. Yeah, the fact that there is this pile of food. And so that's how they are consuming it. And what's happening with women is as their fertility is ending, then they are continuing, given we have evolved to be aging more slowly. They are still big and strong and still putting stuff into the piles, but they're not putting any new little mouths and stomachs. Right. It is their continuum addition to what's available that allows the younger females to then have another baby sooner.

So that's how it looks. So the Hadza tribe that you, that is our modern day version of the grandmother hypothesis, when you, when you watch them, was the grandmother considered purposeful? Was she considered to be really important to the tribe? Was she lifted up? Was there some kind of societal, like, honoring of her that we don't typically do in our modern day world? I would say the answer to that is no, although hudso are very feisty. So, and, and, but I would say it is the case, you know, I just, I think of times when, particularly a few women would really, when there was some kind of hoo-haha going on, be in the

argument. But no, I would not say that there's any sense in which old women are revered. Interesting. So one of the things that when I really dove into looking at the grandmother hypothesis, the way I looked at that was that the culture needed the grandmother. She was pivotal for the whole tribal experience and for generations to continue on. If you juxtapose that to what we do to postmenopausal women now, our society tosses women aside. And one of the things I want to redefine with aging is that actually if women understood that in their postmenopausal years, if they understood their brain, if they understood this regeneration of energy that they were getting back, that they would see the importance that they had in the postmenopausal years.

But our society doesn't look at that. So I am curious if things like Alzheimer's and dementia, if that happens or this obsession with anti-aging that so many women have, if that is happening because we feel like we're going to be tossed aside by our culture. Whereas if you look at the Hadza, you look at our primal friends, that wasn't the case. You just move to the next evolution, evolutionary need for the tribe. Do you have any feeling on that in how it compares to how we handle menopause today? Well, I think the way we look at it today, I completely agree is, you know, I mean, I think it's really sort of creepy when I see, you know, older women who've had all this work and, you know,

I would think they are 12 and, you know, I just, whoa, I wish that isn't what was going on. But I understand it. And all kinds of contexts in which the stuff that you need is actually controlled mostly by males, then finding ways to connect to male is a way to this stuff, well, that you will need for your kids. And so the whole pattern of the kind of sexual division of labor in, in, quote, traditional societies that says, you know, men go forth and bring home what then feeds the domestic worker

that is mom. Well, in foraging societies, women are providing the crucial resources that are reliable and provide what the kids need. And again, it is not unusual in human societies to mark menarche, you know, that there are various kind of ceremonial things around that. Yeah. But the general pattern, and there actually are a bunch of feminist ethnographers who would be, I mean, this is so interesting because I think the biology explains what they're talking about, but for the most part they would say, no, didn't get the biology out of here, or this is just culture, and do not, et cetera, but who have talked about, well, actually the role sex plays in the politics of what we call egalitarian societies, and egalitarian, they complain, and these are

people who say, you talk about this society, I study and call it egalitarian. It is not egalitarian, that the relative position of men versus women is really different. And there is a lot of sexual talk around everything that goes on politically. And the main thing men fight over is women and being dissed because so this coming back to this thing that I was talking about where men competing for their reputation the older guys are always ahead and then dominating the younger guys and you know there are all kinds of ethnographic examples of what the old men do to the young men to keep them in line that that's all part of the same story wow so when I hear that I'm like is feminism ever going to stick in a culture where we

are, have this evolutionary design built within us where the man has got this status and is bringing home the bacon and the woman is the one trying to attract him. Like, when I hear you talk, I'm like, wait a second, whatever could happen in our human life that would make us equal is almost going against our evolutionary biology. And I hate to say that. What do you think of that? I have this amazing student who, after the election, said, oh, this is, it's so horrifying to have been right. But I, we just thought again the resurgence of patriarchy. I mean, it is, and look around the world. It's so I, it's around the world.

It continually repairs sometimes in just these really virulent forms, right? But it is also the case that there are places where it is not the case that the old man can do to the young men. And, you know, so all these complicated conflicts of interest and tradeoffs, they depend and they take different shape in different socioecologies. And I focus especially on the ones that are pre-holocene because that's how we got to be animal. But the thing about recognizing that it's actually midlife menopause that in a sense is where a patriarchy comes from. You know, realize that that's, it's so important. It's just the center of so many things. You know, it's the thing about the socially precocious babies.

That is a consequence of mom moving on and having another baby while you still can't. do anything. And boy, if you don't get somebody, mom come back and somebody, then that's curtains. And so that's that's the kind of thing that Sarah Hurdy was like a hierarchy. So, so when when we look at the grandmother in these tribal situations, one of the things that I noticed, and so, you know, my world has been fasting. And I've taught millions of people how to fast. And the person that does the best with fasting is the post-menopausal woman. And when I brought this to Lisa Mascone's attention, she said yes, because after estrogen goes down, our brains become less sensitive to glucose. So when I go back and look at the grandmother hypothesis, I'm curious if as the grandmother was

grabbing these tubers, what did she feed the children and the fertile women first and then whatever was left over, she ate, which forced her to have to go longer periods without food. Do we have any sense of her frequency of eating back in those days? Well, again, in my experience, what happens is everybody's eating as much as they can, and it's only what isn't that goes back. And one of the reasons the big animals are such a big deal is people come to the kill site and eat their enormous amounts. but it's so enormous that there's still a lot left.

And so that comes back to camp. And these are all things we have measured because of, you know, questions like this, what the hell is going on? But when it comes to eating every day, you know, again, to simplify that what the adult men are doing in our experience with the Hodzahn, again, this is what Woodburn described,

working decades earlier. So that the men go off and they don't have acquire all these reliable things and feed themselves. And again, if they get a small animal, that's no big deal. They just cook it and take it right. And if they're all, then, you know, they'll bring it back. But that might just as easily go to the other men as it goes to any of the women and kids, you know, as Woodburn said. But the real deal is to try to be one of the guys who hits a big one. And everybody knows who it was. But what you get for having, done that is the credit, you don't have any special right to the meat. Everybody, you know,

this is the meat. I'm one of the people. Where's my? And this is another thing about, about Hadsda etiquette, you know, is very insistent. People, where's mine? So the notion that, that, and I think we do know in some kinds of sociocologies where mom is responsible for the hot meal and then dad eats first, and, you know, there are places where that is the pattern. But a guy who's just had so many good ideas, and I think he's right about so many things, but wrong about this, Richard Rangham, who actually, what we know about chimpanzees,

a lot of it's where, you know, Richard is responsible for it, and his setting up this field site, Kanye War is so important, and his students and so on. But he actually has said in a book that men can afford to go, often do risky things because when they come home, there will be, you know, the little lady will have a hook. Boy, that's a lot.

Those story from my experience with foragers, that is not what goes on with the hodzah and not what goes on with the Aceh. And so that notion. Interesting. So the, the, and again, in my experience, it is not the case that older women eat last because the women and children are all eating. together. So it's not, okay, great. And not, you know, again, they are not feeding the men. The men are feeding themselves. Feeding themselves. Yeah. And on, you know, on the reliable resources. So the big

deal is there are certain kinds of things that are reliable. If you go for it, you won't fail. And, and of course, that's crucial if unlike the other eight babies who can, the kinds of things that that everybody's eating, that mom is eating and feeding herself as she carries you along while she's nursing you. Those are things you can manage. And it's also the case that this life history shift to slower development. So what those infants, their motor capacities, are more developed at ages than our babies because, again, this life history has slowed, development, which has had this consequence for the size of our brains and the size of the neocortex and all of that, you know, begins to tie in to this life history. And again, my,

my, you know, memory is always dangerous, right? But when I think of, you know, my, my, my followers with, with hudso women, that in fact, you know, as, as tubers are pulled up the fire, after pretty short time on the fire. And often these are everybody's youth sharing the same fire. And then, you know, the pieces are, everybody, you know, reaches out for a piece. And the little kids get in there. There's no hierarchy to that then. Everybody's eating what they can eat.

Yeah. So when you were looking at the HUDs, the grandmother, as far as her fitness level, like if we look at the Western culture, there's this. understanding that as we age, we're going to, our fitness level is going to go down. But I'm also curious that's because we're sitting all the time and we're not having to be so purposeful with our bodies. What did you see in those grandmothers as far as their capability of fitness that we might gleam some insight as to how we were designed our fitness was supposed to be in those postmenopausal years? Right. Well, this is where language gets in the way,

right? Because there's fitness in the sense of physical condition, right? and then sense of gene copies in the future, right? And those are not the same thing at all. And actually, some really interesting data has come out recently on this aspect of things, comparing energetic expenditure between actually hodza folks and, you know, North American couch potatoes. And so this is Hanser's work and showing that actually when it comes to total energy expenditure, it's not so different if you control for age and sex.

And so the issue about American obesity is all that food. And as Herman says, you know, hodz food is not that good. So I disagree with them. I like potatoes. But we are obsessed with all kinds of delicious things, and you can hardly go to any kind of social gathering without being invited to have something. And then we celebrate with big feasts

that include a lot of fancy stuff. And are the women in the Hads of Tribe as they age? I mean, they're still very physically active, is what I hear. They are. Absolutely. Absolutely. But again, this is the thing, you know, the contrast, big contrast, well, across the primates

that if you're a monkey, adult mortality is higher, you mature early enough not to die before you have kids, and you end up being smaller and so on. But if we just look at the great apes and that, so this hominid now, now we're all in the same hominid family, us and genus Pan, so that's chimpanzees and guineas and bonobos, gorillas, orangutans. We're all hominids, and hominids are the biggest, have the greatest longevity of all the primates, and they have the longest birth intervals.

Well, we have even greater longevity and mature even later, and we have much earlier, much shorter birth spacing. And that was a grandmother's fingerprints, says, you know, at the event that the thing that has favored the postmenopausal longevity, the slower aging generally, because remember Jane Goodall saying, you know, I have 33 is the beginning of old age, and I see all of these ways in which it gets difficult to climb trees, and then, you know, you're subject to the insults that are going to kill you. You get to be old and rarely outlive your fertility if you're a chimpanzee. But what happened in us is if you make it to adulthood, and of course, they're unfortunately, Fortunately, there are some human populations where that's tricky and make it to adulthood.

But once you do, the chances of outliving your fertility if you're female are way better than chance. You are going to outlive menopause. If you're male, you will keep producing sperm. And that sets up all these other things about male stress. Yeah. Would you say that one of the challenges right now with menopause, I mean, menopause is having a moment and we're talking about it, like we said, do you feel like we're living, menopausal women are living at a little bit of an evolutionary mismatch to our design between the way we're treated

by the culture, to the type of food that we're eating, to this understanding that, oh, you're, you know, as you get older, you should be slowing down. Is there some kind of evolutionary mismatch that we are not connecting with when it comes to our post-menopausal years? Well, I think I had a paper in 2003, so that's a long time ago. Anyway, what I was underlining in that paper, I think it was grandmothers and the evolution of human longevity, was how even we tend to think of retirement age of 65, right? And that is well-past menopause, right?

So recognize aging is. is absolutely, well, do we recognize it? That one of the misunderstandings, and I always try to hit this with students, it's so easy for people who know stuff, I wish I knew, you know, who really know all kinds of stuff, really smart, to think that life expectancy is a measure

of whether there are any old people. Because life expectancy, as a demographic parameter, is the average lifespan of everybody born at the same. time. And if you have a population where there's a lot of infant and juvenile mortality, then you have all those really short spans that go into the average and make it really bring it down. All right. Yep. Well said. In these faraging populations, is at birth is well less than 40. and yet, if we actually look at the age structure, about a third of the adult females are past their fertility.

So it's so easy to get confused by the demographic numbers, even George Williams, who was so influential as an evolutionary biologist to me, a very important paper in 1957 about senescence, about aging, and why it varies so much of the living world. I mean, it's a huge contribution, really brilliant. But having laid out the theory, then he said there should be no post-fertile lifespan, life in the normal lifespan of any kind of animal that's characterized by what I've been talking about. And then having said that, he said, oh, yeah, what about menopause?

He was writing in 1957 where everybody thought menopause was unique to us, but we didn't have any of the data we now have on the other apes, where we didn't have any of this demography from people living under mortality regimes of hunting and gathering. And what he did was, brilliant scientists that he was, he tried to, were there any old people in the past? And he used what paleodomographers were saying at the time. They were using these skeletal assemblages and trying to age them from the Upper Paleolithic

and actually the Mesolithic and saying there weren't. And that has all been blown up. They were, you cannot do what they were doing correctly. And so the recognition that actually a life history like ours is very old, that Gina's homo, I mean, the thing that I'm. trying to really underline this thing about committing to the kinds of foods that the babies can't feed themselves on is just a huge game changer. And that is what means then Gienis Homo gets into all these places in the temperate old world and gets big. Interesting. Because of that.

Yeah. Yeah. And that's grandmother affects. Right. Yes. That's right there. What about the orca whales? We hear that they are the only, yeah, where do they fit into this? So interesting. I mean, those cetaceans in general are just fascinating because they have these enormous brains. But it's just so difficult to, you know, to really study them. But, well, actually, interesting that you mentioned that because it's really a pretty nifty paper by, I think Ellis was the first author. This was maybe a year ago or so.

And the person who had the comment on the paper is somebody who I think knows on what stuff that I know. And I was surprised to hear her use Williams as the source of the grandmother hypothesis because that's a thing. One of the few things he got wrong, but he got that wrong. But yeah, no, the orcas are actually the orcas, the big mystery for me with the orcas. and we're finding out interesting new stuff all the time, but there's so much we can't because it's all underwater, you know, it's just occasionally when it's possible to see this. But the way they build their life tables is worrying,

and the mystery from a life history theory theory theory theory perspective is because they are sexual reproducers, so one father, one mother, and so all the genes are shared by both males and females. and yet their age-specific survival curves make it look like the males are all dead at the age that the fertility ends. And then there are all these older females. And yet it's the, quote, really big males that are getting most of the paternities. And so that sets up a real riddle because that should mean selection would favor that those guys would survive

because way more companies are going into future. So, yeah, and so many interesting questions about the workers. And there are a couple of other taxo where people think they have post-fertile females surviving. You know, they have a really interesting social organization the arcas do where everybody stays home and where, you know, males go off and compete to mate with females elsewhere. And then they come back home. And the sisters are fertilized by males from elsewhere. And every once in a while, there's just an amazing sort of anecdote that people record about orcas.

This was off the coast of California where it just happened that the orca watchers were out there. And they saw this male going after a female who had a really new baby and one that was a little older. and he was trying to kill her. So this infanticide thing we know is a thing in primates. So our leader that is, and the whole issue around female counter strategies, given that males can be dangerous, then you better fuck them all because if they have a chance of being a day, then they won't kill it. So I love Sarah Hurdy's calling that being assiduously maternal.

I forget she's so good about that. But here is the orcas in which here's this guy trying to get the baby and he fails. And then there's another attempt. And it turns out that his wingman in this attempt is his mom, who is there helping him knock off the baby to get the next paternity. So, yeah, no, there's so much. So we may not want to compare ourselves to Orrin. of whales. That's what I just heard in that. But bonobos, you know, so another, another closest living relative, we have chimpanzees and bonobos. And bonobos, it turns out they're way more similar

than, anyway, well, I could just go on and on. But anyway, in bonobos, female alliances really play an important role. And it turns out that the paternity skew is even higher in bonobos than it is and chimpanzees, some males getting a larger fraction of the paternities. And the way in which some males get especially many is if their mom is high ranking. So, you know, mom. Interesting. Wow. It gets complicated. So to, yeah, to finish this up, what you, you know, the grandmother hypothesis has been getting more and more attention as menopause is coming in being, in being able to be something we can chat about now. What are you hoping your work with the grandmother hypothesis? What are you hoping that will do to the current menopausal conversation?

What are your insights in how that can help those of us that are navigating our aging years now in this post-reproductive state? What can we learn from this hypothesis? Well, I think the more we know about human life history and how it shapes all of these features of us. I mean, the obvious question is, so what, if you know that, here we are. Right. But among the things that go with being this kind of ape are some things that we really value and cherish. I mean, like this. Am I making sense to you?

Do you? I mean, this is for us talking to somebody. Yeah. And you're really connecting is just such a delight. But it also can be associated with, as you're growing up, how is it that we do that? And I want to, yeah, am I going to fit in here? And what should I? And so learning how to do it right means, okay, that's our way.

Them, they don't do it our way. And we get this really scary, us versus them, antagonistic, dangerous to each other and the planet as part of our capacities and tendencies as this age. And understanding what's going on doesn't make it go away. But one of the things that maybe it can do is make us more charitable toward each other. Yeah. I mean, great. And that's how I fell in love with your hypothesis because I was like, wait, here's the purpose.

there is a purposeful reason we spend so many years in the post-metaposal years. And that's what I... Absolutely. This has evolved because it meant there were more descendant copies of this. It succeeded against, which is why back again to natural selection being this competition within a taxon, you know, rather than for the good of the species because it's, all of that is going on all the time, you know, which, given the current circumstances, which variants tend up doing better and then there are more copies of them and then the whole thing shifts in.

Right. Yeah. Yeah. Well, and a colleague of mine, I guess, at Utah, although she's in psychology, Lisa Diamond, her focus in her research has been sexual fluidity. She started out being especially interested in women, but then started studying it in men and finding there's a lot of sexual fluidity in everybody. But she and her co-author, postdocking with her, whose name I'm forgetting for a minute,

but I will think of that. They have recently made the argument that, based on and actually done the analyses of data sets in which they can control for all kinds of things that might affect aspects of health status. and what they find is when you control for all of those things, you still find that stigmatized minorities, gender minorities, racial minorities, that still you see the health disparities. And their hypothesis is it's the stress that goes with the absence of social safety.

and what I have suggested the Lisa, and since she hasn't done it, I'm suggesting it myself in print, extending that hypothesis to there is what's called the health survival paradox. Do you know about that? No, I don't. That in all kinds of contexts, what you see is that men, well, actually, it starts way earlier that boys, I mean, and then I could talk about, it's a whole other topic I don't want to get into, but anyway, that mortality is higher in males than in females throughout. And yet, females are sicker.

So that's the health survival paradox. And extending Lisa's hypothesis about the stress associated with concern about social safety, Given all the things I've been saying about me or 40, you never know. And I'm talking to a colleague of mine said, you know, if it's ever an evening somewhere and people have come to a lecture hall and then you are talking about stuff like this, just ask the audience if women walking alone to their car in dark are way more worried than if they're with someone. somebody else or if a man is walking to his car. And there are, again, there are all kinds of data.

People studied a lot of this stuff a while ago, and it went out of fashion. But the advantages of having a bodyguard mean that there may be things going on among the males where claiming proprietary, I don't know, ownership of this woman is in his fitness interest. But, and actually this is a thing Nick has said about, in a paper of ours about divorce rates among the hodzah, that actually given the fact that what women are doing, the work they do is so important to the welfare of their kids, that being able to say, see my wedding ring? You know, you don't have wedding rings, but don't hassle me. See, I'm, I'm, it makes her safe. with that guy and therefore leave me alone. Fascinating. It's so fascinating. I mean, my, what I learned in teaching the world about intermittent fasting was that when we go back to

evolutionary biology, we find a lot of the answers to the health challenges we're having today. I completely agree. I mean, that is, you know, for me, I started out as a garden variety cultural anthropologist and it was only, you know, a series of love. lucky breaks where I was led to, wow, go back to evolutionary biology and just discover the powerful tools. I mean, I, you know, wow, we can explain age. We can explain these. Yes. That is so. Yes. And it is very exciting. You know, be one surprise after another. No kidding. We can explain that too. Right. Exactly. So maybe we'll talk again, but I've really, really look forward to seeing where you end up going with all of this. I mean, thank you.

Yes. Oh, yeah. No, I just, you know, when I watched the world heal using fasting, it really got me thinking there's a reason the body does everything and we have to pull it out of the modern context and get it back into this evolutionary state to truly understand it. So, so thank you. I mean, this is, I've been, I've been listening to your podcast. I've been reading your papers. I mean, I've been stalking you and you're not even aware of it. And yeah, I will keep you posted on the next book and I will reach out. But thank you for your work. You know, it's really, it's beautiful to see it being highlighted. Thank you for yours. Yeah. The communication skills are so crucial. So agree. For being effective communicator. Thank you so much for joining me in today's episode. I love

bringing thoughtful discussions about all things health to you. If you enjoyed it, we'd love to know about it, so please leave us a review, share it with your friends, and let me know what your biggest takeaway is.