On Humans

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 male and female. Whether you agree with Fuentes or not, it’s an argument worth taking seriously.We had a great conversation, 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/onhumansMENTIONSAgustín Fuentes: Sex is a Spectrum; Creative Spark; Race, Monogamy, and Other Lies They Told YouYuval Noah Harari: Sapiens, A Brief History of HumankindJared Diamond: Guns, Germs, and Steel Steven Pinker: How the Mind WorksSara 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) | 

Johannes Krause, Director of the Max Planck Institute of Evolutionary Anthropology, dives into humanity's journey from early Homo sapiens to modern civilization. He discusses the transformative Neolithic Revolution, the genetic interactions with Neanderthals, and the complexities of ancient heritages. Krause highlights the influence of horse-riding cultures from the Eurasian steppe on empires and the dichotomy of human expansion versus sustainability. His reflections on our evolutionary path challenge us to consider our future on this planet.

Johannes Krause, a leading expert from the Max Planck Institute for Evolutionary Anthropology, dives into the transformative science of ancient DNA. He explores the wild Ice Age world where Homo sapiens coexisted with Neanderthals and Denisovans. Topics include how climate changes shaped our ancestors' success, the intriguing genetic legacies we share, and the mysterious fate of Neanderthals. With a sprinkle of fantastical island tales and the complexities of human migration, Krause challenges conventional wisdom about our origins and evolution.

Join Chris Stringer, a leading paleoanthropologist at London's Natural History Museum, as he digs into the origins of our species. He unpacks the evolution of the genus Homo, including the surprising interbreeding with Neanderthals. Stringer also explores how diet shaped our expanding brains and the unique prolonged childhoods of Homo sapiens. Intriguingly, he discusses the significance of brow ridges in social signaling and how climate changes have shaped human development over millennia, drawing connections to modern environmental issues.

In this engaging discussion, Dean Falk, a Distinguished Professor of Anthropology and expert on human brain evolution, dives into our evolutionary journey after separating from chimpanzees. She explores the concept of the Botanic Age, where early humans began using botanical tools. Falk highlights the transition to bipedalism that shaped our ancestors and how it intertwined with the origins of language and music. Additionally, she challenges traditional views on brain evolution, suggesting cognitive development began before the Stone Age, offering fresh insights into what makes us uniquely human.

Tim Coulson, Head of Biology at the University of Oxford and author of "A Universal History of Us," takes listeners on a compelling journey through the origins of life on Earth. He discusses how meteors influenced early life, the role of climate change in human evolution, and the profound impacts of the Great Oxidation Event. Coulson also explores the fascinating transition of life from sea to land and how our ancestors thrived alongside dinosaurs. His reflections highlight the remarkable journey of humanity and encourage curiosity about our existence.

Where do we come from? How did we get here? What kind of creature are we?The science of human origins has made great progress in answering these timeless questions. From carbon isotopes to ancient DNA extraction, we now have unprecedented tools to explore our past. But with all this detail, it’s easy to miss the forest from the trees.To fill this gap, On Humans has partnered with CARTA — a UC San Diego-based research unit on human origins. Together, we have designed a five-episode journey to dig deep into the new science of the origins of humankind. Together, these episodes explore the emerging science of how we became the puzzling and wonderful creatures we are today. The series begins tomorrow. Subscribe now free episode and written summaries at:Onhumans.Substack.com/OriginsSERIES OVERVIEW#1 The Big PictureThe series begins with a sweeping take on the history of life on Earth, from the origin of life to the rise of humans.Key questions: What is life? Who were our ancestors during the dinosaurs? What led to the rise of primates? And what kind of a primate are we?Your guide: Tim Coulson is the Head of the Department of Biology at the University of Oxford. He recently released a breathtaking overview of the history of life and the universe titled A Universal History of Us.When: March 25th#2 An Unusual ApeIn episode two, we follow the first steps on the human line, exploring how abandoning life in the trees paved the way for many of our human oddities.Key questions: Why was upright posture so important? What did it do to parents and children? When did the brains of our ancestors start to show human oddities?Your guide: Dean Falk, a leading expert on brain evolution at the University of Florida. She recently published a book titled A Botanic Age, looking at human evolution behind the Stone Age.When: April 2nd#3 What Is a Human?The stage has been set. The third episode tackles human evolution head-on, focusing on the new scientific discoveries about the genus Homo.Key questions: What is a human? Why did we evolve? And how do modern humans differ from Neanderthals or other extinct humans?Your guide: Chris Stringer is an iconic figure in the field, best known for his groundbreaking work towards the widely accepted Out of Africa -theory of human evolution. His career at London’s Natural History Museum stretches across five decades.When: April 9th#4-5: The Story of Sapiens (In Two Parts)The series finishes with two episodes on the story of Homo sapiens, using the magic of ancient DNA to tell a genuinely global history of our species.Key question: How did migrations shape the human story? Why are we the only humans left? And how did humans spread worldwide, first as hunters and gatherers, then as farmers and shepherds?Your guide: In 2010, Johannes Krause became the first person to discover a new species of humans by DNA alone. Co-author of Hubris, and A Short History of Humanity, he is the Director of the Max Planck Institute of Evolutionary Anthropology.When: March 16th & 23rdSUBSCRIBE ⁠Onhumans.Substack.com/Origins⁠

Bishnupriya Gupta, a professor of economics and author, delves into India's post-colonial journey. The discussion highlights the deep-seated legacy of British colonialism and its impact on modern education and economic structures. Gupta contrasts India's economic progress with East Asian nations, uncovering the successes and challenges of its democracy. Key topics include the role of historical educational policies and the divergence in economic strategies between India and countries like South Korea. Insights into inequality and future expectations further enrich this compelling narrative.

Bishnupriya Gupta, a renowned economics professor at the University of Warwick and author of 'An Economic History of India,' dives into the origins of modern India. She discusses the stark differences in living standards between India and England in 1600, highlighting the detrimental impacts of British colonial policies on the Indian economy. Gupta examines the Great Famines of Bengal, revealing British negligence, and critiques both imperial apologists and Indian nationalists. She also connects Mahatma Gandhi's education to India's lag behind East Asia in the 20th century.

Angarika Deb, a cognitive anthropologist at Central European University, dives deep into the origins of gender inequality. She challenges the biological determinism of patriarchy, illustrating that hunter-gatherer societies often showcased gender equality, unlike their agricultural counterparts. Deb explores the unique dynamics of the Bayaka and Akta tribes, revealing egalitarian labor distributions. With thought-provoking examples, she urges listeners to reconsider societal structures and the potential for equitable relationships across cultures.