80,000 Hours Podcast

In many ways, humanity seems to have become more humane and inclusive over time. While there’s still a lot of progress to be made, campaigns to give people of different genders, races, sexualities, ethnicities, beliefs, and abilities equal treatment and rights have had significant success.
It’s tempting to believe this was inevitable — that the arc of history “bends toward justice,” and that as humans get richer, we’ll make even more moral progress.
But today's guest Christopher Brown — a professor of history at Columbia University and specialist in the abolitionist movement and the British Empire during the 18th and 19th centuries — believes the story of how slavery became unacceptable suggests moral progress is far from inevitable.
Rebroadcast: This episode was originally aired in February 2023.
Links to learn more, video, and full transcript: https://80k.link/CLB
While most of us today feel that the abolition of slavery was sure to happen sooner or later as humans became richer and more educated, Christopher doesn't believe any of the arguments for that conclusion pass muster. If he's right, a counterfactual history where slavery remains widespread in 2023 isn't so far-fetched.
As Christopher lays out in his two key books, Moral Capital: Foundations of British Abolitionism and Arming Slaves: From Classical Times to the Modern Age, slavery has been ubiquitous throughout history. Slavery of some form was fundamental in Classical Greece, the Roman Empire, in much of the Islamic civilisation, in South Asia, and in parts of early modern East Asia, Korea, China.
It was justified on all sorts of grounds that sound mad to us today. But according to Christopher, while there’s evidence that slavery was questioned in many of these civilisations, and periodically attacked by slaves themselves, there was no enduring or successful moral advocacy against slavery until the British abolitionist movement of the 1700s.
That movement first conquered Britain and its empire, then eventually the whole world. But the fact that there's only a single time in history that a persistent effort to ban slavery got off the ground is a big clue that opposition to slavery was a contingent matter: if abolition had been inevitable, we’d expect to see multiple independent abolitionist movements thoroughly history, providing redundancy should any one of them fail.
Christopher argues that this rarity is primarily down to the enormous economic and cultural incentives to deny the moral repugnancy of slavery, and crush opposition to it with violence wherever necessary.
Mere awareness is insufficient to guarantee a movement will arise to fix a problem. Humanity continues to allow many severe injustices to persist, despite being aware of them. So why is it so hard to imagine we might have done the same with forced labour?
In this episode, Christopher describes the unique and peculiar set of political, social and religious circumstances that gave rise to the only successful and lasting anti-slavery movement in human history. These circumstances were sufficiently improbable that Christopher believes there are very nearby worlds where abolitionism might never have taken off.
Christopher and host Rob Wiblin also discuss:
Various instantiations of slavery throughout human history
Signs of antislavery sentiment before the 17th century
The role of the Quakers in early British abolitionist movement
The importance of individual “heroes” in the abolitionist movement
Arguments against the idea that the abolition of slavery was contingent
Whether there have ever been any major moral shifts that were inevitable
Chapters:
Rob's intro (00:00:00)
Cold open (00:01:45)
Who's Christopher Brown? (00:03:00)
Was abolitionism inevitable? (00:08:53)
The history of slavery (00:14:35)
Signs of antislavery sentiment before the 17th century (00:19:24)
Quakers (00:32:37)
Attitudes to slavery in other religions (00:44:37)
Quaker advocacy (00:56:28)
Inevitability and contingency (01:06:29)
Moral revolution (01:16:39)
The importance of specific individuals (01:29:23)
Later stages of the antislavery movement (01:41:33)
Economic theory of abolition (01:55:27)
Influence of knowledge work and education (02:12:15)
Moral foundations theory (02:20:43)
Figuring out how contingent events are (02:32:42)
Least bad argument for why abolition was inevitable (02:41:45)
Were any major moral shifts inevitable? (02:47:29)
Producer: Keiran Harris
Audio mastering: Milo McGuire
Transcriptions: Katy Moore

When James Smith first heard about mirror bacteria, he was sceptical. But within two weeks, he’d dropped everything to work on it full time, considering it the worst biothreat that he’d seen described. What convinced him?
Mirror bacteria would be constructed entirely from molecules that are the mirror images of their naturally occurring counterparts. This seemingly trivial difference creates a fundamental break in the tree of life. For billions of years, the mechanisms underlying immune systems and keeping natural populations of microorganisms in check have evolved to recognise threats by their molecular shape — like a hand fitting into a matching glove.
Learn more, video, and full transcript: https://80k.info/js26
Mirror bacteria would upend that assumption, creating two enormous problems:
Many critical immune pathways would likely fail to activate, creating risks of fatal infection across many species.
Mirror bacteria could have substantial resistance to natural predators: for example, they would be essentially immune to the viruses that currently keep bacteria populations in check. That could help them spread and become irreversibly entrenched across diverse ecosystems.
Unlike ordinary pathogens, which are typically species-specific, mirror bacteria’s reversed molecular structure means they could potentially infect humans, livestock, wildlife, and plants simultaneously. The same fundamental problem — reversed molecular structure breaking immune recognition — could affect most immune systems across the tree of life. People, animals, and plants could be infected from any contaminated soil, dust, or species.
The discovery of these risks came as a surprise. The December 2024 Science paper that brought international attention to mirror life was coauthored by 38 leading scientists, including two Nobel Prize winners and several who had previously wanted to create mirror organisms.
James is now the director of the Mirror Biology Dialogues Fund, which supports conversations among scientists and other experts about how these risks might be addressed. Scientists tracking the field think that mirror bacteria might be feasible in 10–30 years, or possibly sooner. But scientists have already created substantial components of the cellular machinery needed for mirror life. We can regulate precursor technologies to mirror life before they become technically feasible — but only if we act before the research crosses critical thresholds. Once certain capabilities exist, we can’t undo that knowledge.
Addressing these risks could actually be very tractable: unlike other technologies where massive potential benefits accompany catastrophic risks, mirror life appears to offer minimal advantages beyond academic interest.
Nonetheless, James notes that fewer than 10 people currently work full-time on mirror life risks and governance. This is an extraordinary opportunity for researchers in biosecurity, synthetic biology, immunology, policy, and many other fields to help solve an entirely preventable catastrophe — James even believes the issue is on par with AI safety as a priority for some people, depending on their skill set.
The Mirror Biology Dialogues Fund is hiring!
Deputy director: https://80k.info/mbdfdd
Operations lead: https://80k.info/mbdfops
Expression of interest for other roles: https://80k.info/mbdfeoi
This episode was recorded on November 5-6, 2025.
Chapters:
Cold open (00:00:00)
Who's James Smith? (00:00:49)
Why is mirror life so dangerous? (00:01:12)
Mirror life and the human immune system (00:15:40)
Nonhuman animals will also be at risk (00:28:25)
Will plants be susceptible to mirror bacteria? (00:34:57)
Mirror bacteria's effect on ecosystems (00:39:34)
How close are we to making mirror bacteria? (00:52:16)
Policies for governing mirror life research (01:06:39)
Countermeasures if mirror bacteria are released into the world (01:22:06)
Why hasn't mirror life evolved on its own? (01:28:37)
Why wouldn't antibodies or antibiotics save us from mirror bacteria? (01:31:52)
Will the environment be toxic to mirror life? (01:39:21)
Are there too many uncertainties to act now? (01:44:18)
The potential benefits of mirror molecules and mirror life (01:46:55)
Might we encounter mirror life in space? (01:52:44)
Sounding the alarms about mirror life: the backstory (01:54:55)
How to get involved (02:02:44)
Video and audio editing: Dominic Armstrong, Milo McGuire, Luke Monsour, and Simon Monsour
Music: CORBIT
Camera operators: Jeremy Chevillotte and Alex Miles
Coordination, transcripts, and web: Katy Moore

What’s the opposite of cancer? If you answered “cure,” “antidote,” or “antivenom” — you’ve obviously been reading the antonym section at www.merriam-webster.com/thesaurus/cancer.
But today’s guest Athena Aktipis says that the opposite of cancer is us: it's having a functional multicellular body that’s cooperating effectively in order to make that multicellular body function.
If, like us, you found her answer far more satisfying than the dictionary, maybe you could consider closing your dozens of merriam-webster.com tabs, and start listening to this podcast instead.
Rebroadcast: this episode was originally released in January 2023.
Links to learn more, video, and full transcript: https://80k.link/AA
As Athena explains in her book The Cheating Cell, what we see with cancer is a breakdown in each of the foundations of cooperation that allowed multicellularity to arise:
 Cells will proliferate when they shouldn't.
 Cells won't die when they should.
 Cells won't engage in the kind of division of labour that they should.
 Cells won’t do the jobs that they're supposed to do.
 Cells will monopolise resources.
 And cells will trash the environment.
When we think about animals in the wild, or even bacteria living inside our cells, we understand that they're facing evolutionary pressures to figure out how they can replicate more; how they can get more resources; and how they can avoid predators — like lions, or antibiotics.
We don’t normally think of individual cells as acting as if they have their own interests like this. But cancer cells are actually facing similar kinds of evolutionary pressures within our bodies, with one major difference: they replicate much, much faster.
Incredibly, the opportunity for evolution by natural selection to operate just over the course of cancer progression is easily faster than all of the evolutionary time that we have had as humans since Homo sapiens came about.
Here’s a quote from Athena:
“So you have to shift your thinking to be like: the body is a world with all these different ecosystems in it, and the cells are existing on a time scale where, if we're going to map it onto anything like what we experience, a day is at least 10 years for them, right? So it's a very, very different way of thinking.”
You can find compelling examples of cooperation and conflict all over the universe, so Rob and Athena don’t stop with cancer. They also discuss:
Cheating within cells themselves
Cooperation in human societies as they exist today — and perhaps in the future, between civilisations spread across different planets or stars
Whether it’s too out-there to think of humans as engaging in cancerous behaviour
Why elephants get deadly cancers less often than humans, despite having way more cells
When a cell should commit suicide
The strategy of deliberately not treating cancer aggressively
Superhuman cooperation
And at the end of the episode, they cover Athena’s new book Everything is Fine! How to Thrive in the Apocalypse, including:
Staying happy while thinking about the apocalypse
Practical steps to prepare for the apocalypse
And whether a zombie apocalypse is already happening among Tasmanian devils
Chapters:
Rob's intro (00:00:00)
The interview begins (00:02:22)
Cooperation (00:06:12)
Cancer (00:09:52)
How multicellular life survives (00:20:10)
Why our anti-contagious-cancer mechanisms are so successful (00:32:34)
Why elephants get deadly cancers less often than humans (00:48:50)
Life extension (01:02:00)
Honour among cancer thieves (01:06:21)
When a cell should commit suicide (01:14:00)
When the human body deliberately produces tumours (01:19:58)
Surprising approaches for managing cancer (01:25:47)
Analogies to human cooperation (01:39:32)
Applying the "not treating cancer aggressively" strategy to real life (01:55:29)
Humanity on Earth, and Earth in the universe (02:01:53)
Superhuman cooperation (02:08:51)
Cheating within cells (02:15:17)
Father's genes vs. mother's genes (02:26:18)
Everything is Fine: How to Thrive in the Apocalypse (02:40:13)
Do we really live in an era of unusual risk? (02:54:53)
Staying happy while thinking about the apocalypse (02:58:50)
Overrated worries about the apocalypse (03:13:11)
The zombie apocalypse (03:22:35)

Producer: Keiran Harris
Audio mastering: Milo McGuire
Transcriptions: Katy Moore

John McWhorter is a linguistics professor at Columbia University specialising in research on creole languages. He's also a content-producing machine, never afraid to give his frank opinion on anything and everything. On top of his academic work, he's written 22 books, produced five online university courses, hosts one and a half podcasts, and now writes a regular New York Times op-ed column.
Rebroadcast: this episode was originally released in December 2022.
YouTube video version: https://youtu.be/MEd7TT_nMJE
Links to learn more, video, and full transcript: https://80k.link/JM

We ask him what we think are the most important things everyone ought to know about linguistics, including:
Can you communicate faster in some languages than others, or is there some constraint that prevents that?
Does learning a second or third language make you smarter or not?
Can a language decay and get worse at communicating what people want to say?
If children aren't taught a language, how many generations does it take them to invent a fully fledged one of their own?
Did Shakespeare write in a foreign language, and if so, should we translate his plays?
How much does language really shape the way we think?
Are creoles the best languages in the world — languages that ideally we would all speak?
What would be the optimal number of languages globally?
Does trying to save dying languages do their speakers a favour, or is it more of an imposition?
Should we bother to teach foreign languages in UK and US schools?
Is it possible to save the important cultural aspects embedded in a dying language without saving the language itself?
Will AI models speak a language of their own in the future, one that humans can't understand but which better serves the tradeoffs AI models need to make?
We’ve also added John’s talk “Why the World Looks the Same in Any Language” to the end of this episode. So stick around after the credits!
Chapters:
Rob's intro (00:00:00)
Who's John McWhorter? (00:05:02)
Does learning another language make you smarter? (00:05:54)
Updating Shakespeare (00:07:52)
Should we bother teaching foreign languages in school? (00:12:09)
Language loss (00:16:05)
The optimal number of languages for humanity (00:27:57)
Do we reason about the world using language and words? (00:31:22)
Can we communicate meaningful information more quickly in some languages? (00:35:04)
Creole languages (00:38:48)
AI and the future of language (00:50:45)
Should we keep ums and ahs in The 80,000 Hours Podcast? (00:59:10)
Why the World Looks the Same in Any Language (01:02:07)
Producer: Keiran Harris
Audio mastering: Ben Cordell and Simon Monsour
Video editing: Ryan Kessler and Simon Monsour
Transcriptions: Katy Moore

It’s that magical time of year once again — highlightapalooza! Stick around for one top bit from each episode we recorded this year, including:
Kyle Fish explaining how Anthropic’s AI Claude descends into spiritual woo when left to talk to itself
Ian Dunt on why the unelected House of Lords is by far the best part of the British government
Sam Bowman’s strategy to get NIMBYs to love it when things get built next to their houses
Buck Shlegeris on how to get an AI model that wants to seize control to accidentally help you foil its plans
…as well as 18 other top observations and arguments from the past year of the show.
Links to learn more, video, and full transcript: https://80k.info/best25
It's been another year of living through history, whether we asked for it or not. Luisa and Rob will be back in 2026 to help you make sense of whatever comes next — as Earth continues its indifferent journey through the cosmos, now accompanied by AI systems that can summarise our meetings and generate adequate birthday messages for colleagues we barely know.
Chapters:
Cold open (00:00:00)
Rob's intro (00:02:35)
Helen Toner on whether we're racing China to build AGI (00:03:43)
Hugh White on what he'd say to Americans (00:06:09)
Buck Shlegeris on convincing AI models they've already escaped (00:12:09)
Paul Scharre on a personal experience in Afghanistan that influenced his views on autonomous weapons (00:15:10)
Ian Dunt on how unelected septuagenarians are the heroes of UK governance (00:19:06)
Beth Barnes on AI companies being locally reasonable, but globally reckless (00:24:27)
Tyler Whitmer on one thing the California and Delaware attorneys general forced on the OpenAI for-profit as part of their restructure (00:28:02)
Toby Ord on whether rich people will get access to AGI first (00:30:13)
Andrew Snyder-Beattie on how the worst biorisks are defence dominant (00:34:24)
Eileen Yam on the most eye-watering gaps in opinions about AI between experts and the US public (00:39:41)
Will MacAskill on what a century of history crammed into a decade might feel like (00:44:07)
Kyle Fish on what happens when two instances of Claude are left to interact with each other (00:49:08)
Sam Bowman on where the Not In My Back Yard movement actually has a point (00:56:29)
Neel Nanda on how mechanistic interpretability is trying to be the biology of AI (01:03:12)
Tom Davidson on the potential to install secret AI loyalties at a very early stage (01:07:19)
Luisa and Rob discussing how medicine doesn't take the health burden of pregnancy seriously enough (01:10:53)
Marius Hobbhahn on why scheming is a very natural path for AI models — and people (01:16:23)
Holden Karnofsky on lessons for AI regulation drawn from successful farm animal welfare advocacy (01:21:29)
Allan Dafoe on how AGI is an inescapable idea but one we have to define well (01:26:19)
Ryan Greenblatt on the most likely ways for AI to take over (01:29:35)
Updates Daniel Kokotajlo has made to his forecasts since writing and publishing the AI 2027 scenario (01:32:47)
Dean Ball on why regulation invites path dependency, and that's a major problem (01:37:21)

Video and audio editing: Dominic Armstrong, Milo McGuire, Luke Monsour, and Simon Monsour
Music: CORBIT
Coordination, transcripts, and web: Katy Moore