September 08, 2025

582. Our Ancestral Eves: How the Female Body Shaped Human Evolution feat. Cat Bohannon

1 hour 5 minutes

What does the female body itself contribute to the story of human survival and development, and how does it differ from other animals and specifically, other mammals? These contributions include but are not limited unique attributes for gestation, childbirth, and lactation.

Cat Bohannon is a researcher, scholar, and the author of the book Eve: How the Female Body Drove 200 Million Years of Human Evolution.

Greg and Cat discuss the significant role of the female body in human evolution. Cat shares the origins of her interdisciplinary approach to writing the book. Their conversation explores the evolutionary importance of maternal and infant health, the implications of sex differences in biology, the historical intersections of gynecology and sexism, and the deeply ingrained cultural norms around reproduction. Their discussion also touches on the origins of patriarchy and the impact of modern medical advancements on child-rearing and fertility trends.

*unSILOed Podcast is produced by University FM.*

Episode Quotes:

The deep story of mammals is reproductive investment

06:13: “Eve,” [the book] in so many ways, was just—it's like a giant thought experiment, right? Like, okay, what if we do take this seriously? What if we say, what if sex differences do matter? What does the current science say about where they might and what that might implicate? And how does that change the story of ocean? You know, because like the big story, like you say, of mammalian evolution is reproduction. It's reproduction. I mean, it's cool that some little bit of a quasi-reptilian jaw broke off and now we have inner ear bones, but that's not a really interesting story in evolution. You know what I mean? 06:53: You know, that's not the deep story of mammals. The deep story of mammals is reproductive investment.

Why are female bodies always regulated across cultures?

59:52: We seem to, in every human culture, create rules that regulate access to female bodies. One way or another, we may have a subset of rules that are more liberal—that is distinct to our culture. We may have a set of rules that are more what we would call conservative or more controlling. That is distinct to our culture. It just depends on which culture you are in. What we all do have is these damn rules.

Lactation is a two-way communication system

55:40: We have to think of lactation then as this kind of two-way communication platform between the maternal body and the offspring's body, right? So whether that kid's getting stressed and there's more cortisol in its saliva, or whether the mothers experiencing a stressful environment, then they are effectively biochemically communicating that to one another through that bi-directional transfer point of the damn nipple, which is one incredibly cool. There's nothing like that in the animal world. Two. Oh, okay. So then we have to think of lactation as a thing that's more than simple caretaking. It's actually a major foundational thing that happens in mammals that have nipples.

Why women store special fats in their hips and butt

45:28: One of the things that is really interesting is that on the maternal body, different fat depots seem to have slightly different chops... [45:48] So this gluteal femoral fat, that is your upper thighs, your hips, and your butt — those fat deposits seem to specially store different kinds of stuff. There are these long-chain fatty acids, LCFAs — long-chain polyunsaturated fatty acids. Our bodies are not good at making them from different parts. [46:26] For females, we mostly seem to store them in our butts. We start storing them in childhood, and then we keep going, and it turns out they do seem to be really important for building baby brains and baby retinas, which, by most accounts, are just an extension of your brain anyway.

Show Links:

Recommended Resources: