On Humans is back from the break!

To mark the summer heat, here is a two-part series on how climate has shaped the human story. In next week's episodes, we will explore the role of water and weather in the origins of European colonialism. But today, we start by crawling deeper into the past: to the origins of humanity itself.

In this episode, Yale professor Jessica Thompson helps us navigate one of the most influential ideas in human evolution: that an ancient climate change pushed our ancestors out of the jungle, onto the savanna, and eventually toward big brains, meat-eating, and tool use.

This is a captivating story. It has been mentioned many times on the show. But do the details hold up?

What follows is a sweeping account of human origins, which nuances — but does not reject — the grand arc explored in The Origins of Humankind series. This is a story about a climate that has never remained steady. It serves as a poignant reminder of the weather's power to shape human destiny. But it’s also a story about human resilience and our capacity, from the very beginning, to defy the iron laws of ecology. Enjoy!

Thoughts about the episode? Share them at OnHumans.Substack.com⁠. You'll also find a bunch of links to dig deeper.

SUPPORT THE SHOW

You can pledge your support at Patreon.com/OnHumans⁠

MENTIONED SCHOLARS

Richard Wrangham (guest in summer 2023)

Sarah Blaffer Hrdy (guest in Spring 2024)

KEYWORDS

Human evolution | Human origins | Paleoanthropology | Human biology | Climate change | Miocene | Pleistocene | Brain evolution | Brain energetics | Deep history | Anthropology | Archaeology | Austrolopithecins | Genus homo | Bipedalism | Evolution of apes | Missing link | Tsetse flies |

Binary thinking is out of fashion. But what about biological sex?

Whatever we might say about diversity and fluidity, the ideas of “male” and “female” seem essential in biology. I’ve taught the subject. I’ve drawn bees and flowers, with arrows from anthers to ovaries. I’ve used the terms “dad cell” and “mother cell” while doing so. I don’t know how I could have done it any differently.

And maybe that’s just fine. Human sex cells are binary: sperm and egg. But here’s the twist: humans aren’t sex cells. Humans are animals. And animals aren’t so easily grouped. XY chromosomes don’t always produce a penis. And when we turn to hormones, brains, and behaviours, the picture gets even messier.

Or so argues Princeton Professor Agustín Fuentes, a leading expert on human biology. His new book, Sex Is a Spectrum, came out this week. It makes the case that biology no longer supports a sharp separation between the male and the female.

I approached this topic with a mix of curiosity and scepticism. And while I'm still unsure of what to make of the conclusion, I do not regret the conversation one bit. We had a great chat, ranging from hermaphroditic worms to sex-changing fish, and from gender stereotypes to intersex humans. At times, I pushed back. But I learned a lot throughout the conversation. I hope you do, too.

Thoughts about Fuentes’s argument? Or my takes? Share them at onhumans.substack.com. You'll also find more links to dig deeper.

Support the show: patreon.com/onhumans

MENTIONS

Agustín Fuentes: Sex is a Spectrum; Creative Spark; Race, Monogamy, and Other Lies They Told You

Yuval Noah Harari: Sapiens, A Brief History of Humankind

Jared Diamond: Guns, Germs, and Steel

Steven Pinker: How the Mind Works

Sara Blaffer Hrdy: Father Time (see episode in April 2023)

KEYWORDS

Biological sex | gametes | chromosomes | intersex | hermaphrodite | sex determination | sexual dimorphism | sex-changing fish | clownfish biology | evolutionary biology | human evolution | Agustín Fuentes | anthropology of sex | reproductive biology | nonbinary biology | developmental biology | sex differences | male and female | sex in animals | sex in humans | genetics of sex | human biology | science of sex | sex vs gender | c. elegans sex | 5-alpha-reductase type 2 deficiency (5α-R2D) | PCOS (Polycystic Ovary Syndrome) |

And so it ends! In the final episode of The Origins of Humankind, we explore the aftermath of the story so far—the story of how one peculiar species, Homo sapiens, evolved, spread, and outlived its relatives.

Guiding us through this final chapter is Johannes Krause once again. Together, we uncover the emerging picture of the global spread of farming, pastoralism, and other key ingredients of modernity. Along the way, we explore some of the central questions of history—from the origins of inequality to the surprisingly pivotal role played by the peoples of the Eurasian steppe. (Yes, Mongols will make an appearance! But the story of the steppe goes much deeper...)

As always, we end with my guest’s reflections on humanity.

Enjoy!

LINKS

More material: ⁠⁠⁠⁠OnHumans.Substack.com/Origins⁠⁠⁠⁠

Support the show: ⁠⁠⁠⁠Patreon.com/OnHumans⁠⁠⁠⁠

Free lectures on human origins: ⁠⁠⁠⁠CARTA⁠⁠⁠⁠

Krause's books: ⁠⁠A Short History of Humanity⁠⁠; ⁠⁠Hubris: The Rise and Fall of Humanity⁠⁠

ABOUT THE SERIES

The ⁠⁠Origins of Humankind ⁠⁠is produced by On Humans and UC San Diego's Centre for Academic Research and Training in Anthropogeny (⁠⁠CARTA⁠⁠). Other guests include Chris Stringer, Dean Falk, and Tim Coulson.

KEYWORDS

Anthropology | Biology | Human evolution | Human origins | Homo sapiens | Agriculture | Ancient DNA | Climate changes | Pleistocene | Holocene | Archaeology | Neolithic | Yamnaya | Bell Beakers | Proto Indo-Europeans | Ötzi Ice Man | Gunpowder Empires | Bantu-expansion | Austranesian expansion | Sami poeple | Y-chromosome bottleneck |