On Humans

You decided to start reading this. But could you have chosen otherwise?

In this short epilogue to this fall's brain science -series, Oxford biologist Tim Coulson gives his defense of free will.

(The episode is an unheard clip from the conversation with Tim Coulson, originally recorded as part of the Origins of Humankind -series in March 2025. )

LINKS

For highlights, longer quotes, and references, see my essay at OnHumans.Substack.com.

Tim Coulson's book is called The Universal History of Us (in the UK) and The Science of Why We Exist (in the US).

For more episodes on the human brain, check ⁠⁠OnHumans.Substack.com/Brain⁠⁠

Want to support the show? Join the club at ⁠⁠Patreon.com/OnHumans⁠⁠

MENTIONS

Names: Albert Einstein | Niels Bohr

Terms and concepts: free will | many worlds -interpretation vs the Copenhaguen interpretation of quantum mechanics | Brownian motion | Quantum biology | stochasticity vs determinism | neural integration vs complexity | chance & necessity | philosophy | physics | biology | neuroscience

Science has learned much about the brain. But how well do we understand this organ of the mind? Are we even close to cracking the neural code? Is a groundbreaking theory of consciousness just around the corner?

In this final episode of the brain science -series, Matthew Cobb takes us on a tour of the story of neuroscience. We meet many colourful characters, but this is not just a history for history’s sake. More importantly, this is a reflection on the increasingly clear limits that brain science is coming up against — limits often left invisible behind the thirst for stories about new discoveries. 

Enjoy!

FACT CHECKING

Contrary to the precise phrasing in the episode, a handful of new psychiatric drugs have entered the market recently. The general observation remains well-supported.

If you spot an error in this or other episodes, please reach out on ⁠⁠Substack⁠⁠ or via ⁠⁠email⁠⁠.

LINKS

Matthew Cobb’s book is ⁠The Idea of the Brain: The Past and Future of Neuroscience ⁠

For more episodes on the human brain, check ⁠OnHumans.Substack.com/Brain⁠

Want to support the show? Join the club at ⁠Patreon.com/OnHumans⁠

MENTIONS

Names: Matthew Cobb | Galen | Aristotle | Andreas Vesalius | William Harvey | William Shakespeare | Queen Victoria | Karl Marx | Pierre Paul Broca | René Descartes | Eve Marder | David Marr | Francis Crick | Geoffrey Hinton | John Hopfield | Warren McCulloch | Walter Pitts | John von Neumann | Alan Turing | Kenneth Craik | Sir John Eccles | Elon Musk | Nicolaus Copernicus | Galileo Galilei

Terms and concepts: recurrent laryngeal nerve | phrenology | localization of function | strokes/aphasia | Broca’s area | plasticity | hemispheric lateralization | corpus callosum | split-brain | consciousness | anesthesia (halothane, etc.) | drugs & neuromodulators | SSRIs | serotonin | dopamine | psychedelics | obster stomatogastric ganglion | three-body-problem | EEG “brainwaves” (gamma, theta, etc.) | David Marr’s levels | neural code | PDP / connectionism | backpropagation | LLMs (e.g. ChatGPT, DeepSeek) | biological plausibility vs engineering | von Neumann architecture | McCulloch–Pitts logical neurons | neural correlates of consciousness (NCC) | “Jennifer Aniston” cells | single-unit recording | connectomics | Human Brain Project | cochlear implants | BCI / robotic arm control | tetraplegia | problem of consciousness | enactive cognition

Dopamine. Serotonin. Endorphins. We have all heard these terms. And these are not just scientific curiosities. Few are those who have never wondered if their brain chemicals are "just off balance".

So how accurate are the popular theories about these mythic molecules?

To guide us through the topic, I'm joined by Judy Grisel—an ex-addict and a world-leading neuroscientist of addiction.

We will discuss all the main elements of brain chemistry by using drugs and addictions as a window into the topic. Towards the end, we also search for ways to better help those who struggle with addiction.

As always, we finish with my guest's reflection on humanity.

DIG DEEPER

This episode is part 4 of this autumn's brain science series. See more

at ⁠⁠OnHumans.Substack.com⁠/brain⁠⁠

Judy Grisel’s book is Never Enough: The Neuroscience and Experience of Addiction

Want to support the show? Join the club at Patreon.com/OnHumans.

FACT-CHECKING

No major mistakes have been found so far.
As a minor note, the SSRI study we mention in healthy volunteers primarily assessed cognitive processing (reinforcement learning/sensitivity) rather than self-reported “emotional flattening”; however, general blunting of emotional responses in healthy participants has been reported by earlier researchers.

If you spot an error in this or other episodes, please reach out on Substack or via email.

KEYWORDS

Names mentioned: Kent Berridge | Mark Lewis | Barbara Sahakian | Trevor Robbins

Technical concepts: dopamine | wanting vs liking | serotonin (5/HT) | serotonin receptor 2A | selective serotonin uptake inhibitors SSRIs | GABA vs glutamate | endorphins | endocannabinoids | alcohol | cocaine | MDMA | psychedelics | behavioral addictions (e.g. porn) | runner's high | cannabis / THC | neurogenesis & pruning | brain plasticity | SSRIs | MDMA (SERT reversal) | emotional blunting | opponent-process theory (A→B) | addiction as disease vs learned state | meaning, motivation, recovery

Our brains can feel remote and abstract. Hidden behind Latin names and textbook diagrams, they rarely feel as personal to us as our hearts and stomachs.

In this episode, neurologist and author Pria Anand helps us get a little more intimate with that grey, wrinkly seat of our consciousness.

Together we explore both the structural architecture and the musical synchronies of the brain. We travel across the left and the right brain, "listen" to the meaning of different brain waves, and discuss some of the most perplexing examples from the annals of neuroscience. What emerges is not just an intimate journey through the organ that makes us who we are, but also an exploration on the meaning of pain, identity, and storytelling.

As always, we finish with my guest's reflection on humanity.

DIG DEEPER

This episode is part 3 of this autumn's brain science series. See more

at ⁠⁠OnHumans.Substack.com⁠/Brain⁠⁠

📖 Dr Anand's new book is The Mind Electric: A Neurologist on the Strangeness and Wonder of Our Brains

Want to support the show? Join the club at Patreon.com/OnHumans

FACT CHECKING

No major mistakes have been found so far.

As a small correction, the patient with conflicting career goals did not, when asked, want to be an "architect", but a "draftsman". See "A Divided Mind" by Joseph LeDoux and colleagues (free PDF).

If you find a mistake in this or other episodes, you reach out directly to at Substack.com/OnHumans or via email.

KEYWORDS

Names mentioned: Michael Gazzaniga | Joseph LeDoux | Patient P.S. | Henry Molaison (H.M.) | William Halsted | Julius Caesar | Fyodor Dostoevsky | Dr. Strangelove | Matthew Cobb | Suzana Herculano-Houzel

Terms and concepts discussed: neurology | neuropsychology | brain damage | lesions | REM sleep (rapid eye movement) | paradoxical sleep | REM atonia | narcolepsy | sleep apnea | Parkinson’s disease | dementia | slow-wave sleep | EEG (electroencephalography) | brain oscillations | alpha waves | theta waves | seizure | epilepsy | focal seizure | generalized tonic-clonic seizure | aura | déjà vu | phantom smell (olfactory hallucination) | corpus callosum | callosotomy | anterior cerebral artery | cerebral aneurysm | hemispatial neglect | apraxia | alien hand (anarchic hand) | visual cortex | language dominance (left hemisphere) | thalamus | somatosensory cortex | limbic system | hippocampus | mesial temporal lobe | anterior temporal lobectomy | anterograde amnesia | retrograde amnesia | Korsakoff dementia (Wernicke–Korsakoff) | transient global amnesia | posterior cortical atrophy | aphasia | confabulation | nociception | lidocaine | dissociative anesthetic | epidural anesthesia | spinal anesthesia | paralytic (neuromuscular blocker) | neocortex | cortex | brainstem | cerebellum | cerebellar lesion | ataxic dysarthria | folia (cerebellar) | trunk (elephant, motor control) | Buddha’s “two arrows” parable

Here is a simple story about the origins of the human brain: All primate brains are dense with neurons—they are the supercomputers of the animal world. What's more, the human brain is just what you’d expect from a primate of our size: big, packed with neurons, but no more special than that. It's the chimps and gorillas who are special: without cooked food, their brains lacked the fuel to keep up with the growing body.

Or so argued Suzana Herculano-Houzel, my guest in last week's episode.

In today's episode, paleo-neurologist Dean Falk explains why she thinks this is only part of the story.

I'll let her tell you why.

Enjoy!

DIG DEEPER

This episode is part 2 of this autumn's brain science series. See more

at OnHumans.Substack.com⁠/Brain

See also last spring's episode with Dean Falk on toolmaking and childhoods, as part of the Origins of Humankind -series.

SUPPORT THE SHOW

OnHumans.Patreon.com

MENTIONS AND KEYWORDS

Scholars

Charles Darwin | Dietrich Stout | Robin Dunbar | Katarina Semenderfi | Weiwei Men | Joseph Ledoux | Jane Goodall

Technical terms

Endocasts | Sulci and gyri | Broca's area | Brodmann Area 10, also known as BA10 and the frontal pole | Acheulean hand axe technology

Keywords

Brain science | Neuroscience | Neurology | Paleoneurology | Evolutionary Anthropology | Comparative Anatomy | Cognitive Archaeology | Origins of Consciousness

I'm excited to announce that On Humans is launching a new series this fall! This one will explore the wonders of the human brain. The new episodes will drop throughout September and early October.

To set the stage, we will revisit a conversation with neuroscientist Suzana Herculano-Houzel, newly re-edited and remastered. It’s the simplest and most elegant story I’ve heard about how our brains came to be — and it sets the stage for the debates to follow.

Enjoy!

DIG DEEPER

Herculano-Houzel's book is called The Human Advantage.

Check out the series page at OnHumans.Substack.com/Brain

For more on human evolution, see the full series on the Origins of Humankind.

SUPPORT THE SHOW

You can pledge your support at ⁠⁠⁠⁠Patreon.com/OnHumans⁠⁠⁠⁠⁠

KEYWORDS 

Human evolution | Brain evolution | Neuroscience | Biology | Anthropology | Cerebral Cortex | Neuron counting | Comparative neurology | Comparative biology | Comparative anatomy | Harry Jerrison | Paleoanthropology | Human origins |

Why did the great powers of Asia stagnate whilst Europe was rising? This question—often called the Great Divergence—is one of the most defining questions of modern history.

Few case studies illuminate this question as well as the contrast between Britain and India. Did colonialism make Britain rich and India poor? Or was Britain’s rise already underway before conquest? And what does all this tell us about the everyday experiences of the people of on two sides of the divide?

This episode is a live recording from the British Academy, where I was invited to speak at the launch of Bishnupriya Gupta’s An Economic History of India. I was honoured to give this talk on this exceptionally rich topic, speaking after some of the leading experts of India's history.

How did I do?

Share your thoughts in the comments at OnHumans.Substack.com.

Enjoy!

DIG DEEPER

Read: See my article on the ⁠"Origins of Modern India⁠⁠". Complement with "Origins of Modern China" from last fall.

Listen: Check out the two-part "⁠What About India?⁠" series from this February. Complement with the episode with Professor Tirthankar Roy this July.

SUPPORT THE SHOW

You can pledge your support at ⁠⁠⁠Patreon.com/OnHumans⁠⁠⁠⁠

KEYWORDS 

Big history | Economic History | Why the West | Gunpowder empires | Mughals | Colonialism | Imperialism | British East India Company | European colonialism | History of Colonialism | Geographical Determinism | Environmental Determinism | Political History | Fiscal History | Great Divergence | Western Dominance | Early Modern History | Kenneth Pomerantz | Steven Broadberry

Climate. Weathers. History.

Here's an encore episode to wrap up the mini-series on these themes!

This episode on the puzzling origins of farming is one of my all-time favourites on the show. I thought it was a good time to put it out again.

You can also read my essay on the topic ⁠here⁠.

Enjoy!

~

ORIGINAL SHOW NOTES

Agriculture changed everything. Traditionally, this “Neolithic Revolution” was celebrated for opening the gates of civilisation. Recently, it has been compared to the original sin. But whatever our take on agriculture, we should be puzzled by one thing: Why did our ancestors start to farm in the first place?

It's not like early farmers had improved lives. Quite the opposite, they worked harder and suffered from worse health. So why did so early farmers stick to it? And why did farming spread so far and wide?

⁠Andrea Matranga⁠ thinks he has the answer. 

An economic historian at the University of Torino, Matranga links agriculture to climate change. This is not a new idea — not as such. After all, agriculture developed in lockstep with the end of Ice Ages. For years, this vague link has formed my own pet-theory on the matter.

But I never paused to reflect on the obvious problem with it. There was never an “Ice Age” in Sudan. Why didn’t humans just farm there? 

Matranga has the answer to this and many other puzzles. And surprisingly, his answer is linked to the movements of Jupiter. I will let him tell you why.

We begin this episode covering some previous theories on the origins of agriculture. Next, we dissect Matranga's theory and the evidence for it. Towards the end, we talk about the spread of farming — peaceful and violent — and note a neglected downside to the hunter-gatherer lifestyle. As always, we finish with my guest’s reflection on humanity.

LINKS

You can find my summary of Matranga's theory with links to academic articles at ⁠⁠⁠⁠OnHumans.Substack.com⁠⁠⁠⁠.

Do you like On Humans? Join the group of patrons at ⁠⁠Patreon.com/OnHumans⁠⁠!

MENTIONS

Names

V. Gordon Childe | Jared Diamond | Mo Yan | Alain Testart | Robert J. Braidwood | Milutin Milanković | Feng He | James Scott | Richard B. Lee | Irven Devore

Terms

Neolithic | Holocene | Pleistocene | Consumption smoothing | Malthusian limit | Milankovitch cycles

Ethnic groups

Natuffians | Pacific Northwestern hunter-gatherers

Keywords

Anthropology | Archaeology | Big History | Economic History | Agricultural Revolution | Neolithic Revolution | Homo Sapiens | Sapiens | Climate change | Paleoclimatology | Seasonality | Origins of Agriculture | Neolithic Revolution | Climate Change | Hunter-Gatherers | Human Civilization | Population Growth | Sedentary Lifestyle | Subsistence Farming | Evolutionary Adaptation | State Violence | Agricultural Coercion | Ancient DNA

Before they built empires, the Europeans built ports.

Across Africa and Asia, European sailors arrived as merchants. They traded and negotiated. They defended their interests—sometimes with cannon fire. But they were not trying to govern a foreign land.

Yet things changed.

Why?

Historian Tirthankar Roy has a bold new answer.

Roy is a professor at the London School of Economics, where he teaches a renowned course on the economic history of colonialism.

His most recent book isThe Origins of Colonialism. And in it, Roy explains that we cannot understand the origins of European Empires in Asia and Africa by simply zooming into the actions of Europeans. We must understand what happened to the elites of the lands being conquered. And more often than not, that had to do with the rains, rivers, and access to water.

In this episode, Roy explains how his theory sheds light on the rise of the British Empire in India. Along the way, we also sketch many broader ideas about the story of global colonialism, from Chinese ports to the conquest of Burma and from the water problems of Mumbai to the rubber plantations of Congo.

Enjoy!

This is part two of this summer’s mini-series on the way climate has shaped the human story. Curious to hear more? Head to last week’s episode on how an ancient climate change paved the way for the very origins of humanity!

Thoughts about Roy’s points? Or mine? Voice them at OnHumans.Substack.com! (Episode page uploaded within an hour of the episode drop.)

SUPPORT THE SHOW

You can pledge your support at ⁠Patreon.com/OnHumans⁠⁠

DIG DEEPER

Check out also the two-part "What About India?" series from this February!

KEYWORDS 

Colonialism | Imperialism | British East India Company | European colonialism | Africa | Asia | India | China | History of Colonialism | Geographical Determinism | Environmental Determinism | Political History | Military History | Fiscal History | Great Divergence | Western Dominance | Early Modern History

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 |