What was the most important transition in human history, the thing that most drastically altered our species' way of life? David Reich's lab has found evidence pointing to a new answer.
— Dwarkesh Patel (@dwarkesh_sp) May 9, 2026
There are two standard candidates:
1. The shift from hunting and gathering to farming, around… pic.twitter.com/649RdS9Bl4
Interesting. I would think that the recent explosion of tech would be a similar driver, but it’s happening too fast to affect natural selection.
So we stopped selecting for intelligence 2000 years ago. Seems about right.
Everyone’s an expert about something but I’d argue that the understanding of germ theory and development of antibiotics is a stronger influence – perhaps not in a positive direction.
I think that’s more a reversal of the bronze age changes. My take is look at the selection events. For the Bronze Age that would be disease and collapse of organized societies. For example, there are multiple historic plagues that wiped out large percentages of people. This would have been worse during the Bronze Age, because a lot of these diseases came out for the first time, spread over new trade routes and infecting vulnerable, large populations.
Germ theory+antibiotics is a partial reversal of that selection process.
A second selection process is repeated cycles of societal build up and collapse. What sort of traits combine to not only enable survival during times of societal collapse (which routinely involve a lot of famine and war), but also readily spread during times of societal growth?
Basically, you’re looking for traits that do well in two very different scenarios. I think there is a place for intelligence in that.
You should watch the whole interview. He says that while people think that evolution is in a period of “quiescence” it has actually been speeding up.
The “Bronze Age” is kind of an antiquated concept, as civilization per se developed in the Chalcolithic, with an end-stage neolithic tool kit to which was added “easy metal” smelting (gold and copper, with natural arsenical bronze). The invention of stannic bronze spread from the middle east after the development of long-range trade. Tin is rare. China imported the invention of stannic bronze from neighboring Uralic nomads, who got it from the illiterate Andronovo culture, who got it from peoples to their south and west. China would never have developed stannic bronze on their own, any more than the Americas did.
There were societies in the Americas that used bronze prior to contact with the Europeans. This was several thousand years later than it was used in the old world but they also used copper several thousand years earlier than the old world. Much like agriculture, it was an independent discovery.
The interesting question is what happened that allowed people all over the earth to make these discoveries at roughly the same time while for much of human history it is thought that no one did any of these activities?
The actual metallurgy is important though. Many societies had non-tool metals, such as arsenical bronze. The discoveries weren’t made at the same time. Stannic bronze was discovered once and spread across the Old World fairly rapidly.
Some Native Americans had stannic bronze. They had talented metal workers. They used metal for tools, weapons, armor, trade, ornaments, and ceremony. It didn’t play out the same way it did in the old world for a variety of reasons but they did have large complex societies that built big cities.
To me, it is interesting that we had these independent discoveries by people around the world at roughly the same time. Maybe it was because the climate was favorable enough to let this happen, maybe there were some genetic changes at the end of the last glaciation, both, or maybe something else.
We don’t have evidence for any of these advancements for most of human history and then in a few thousand years, they happen all over. How things played out in the old world was different than the new, which is to be expected as the conditions are different and real life isn’t like a tech tree in a video game. I suspect the horse was a big influence in spreading genes and technology in the old world, which was missing in the new world. A Europe without horses would be a very different place.
You might enjoy the series from North 02 about metals in the Americas. They did do some inexplicable things, like using copper before it was used in the old world and then just giving it up.
https://www.youtube.com/watch?v=tfwjM4e42cE
Discovery of paternity. Once men realized that sex wasn’t just fun, but also made them as much parents as women were, they suddenly had a very personal stake in the futures of their communities. The territorial and survivals instincts were then triggered on behalf of their children (once they developed a social institution for restricting female sexual autonomy, so a man could be confident that his woman’s children were *his* offspring), leading to Leadership by Fathers (Patriarchy), and thence to civilization as men were now motivated to work themselves into early graves for the benefit of their bloodlines.
That’s my guess anyway.
The shaman whispered to the lugal, “We can’t use all this pussy by ourselves. Let’s use it to get the other men to work and give us their output so we can control everything.” I used to joke, If I became homeless, my begging sign would say, “Will work for pussy.”
I would suggest that the real driver wasn’t so much the bronze as the Yamnaya’s (proto-Indo-European) horses, wagons, and chariots. Evidence of that would be the massive percentage of the world’s population that speaks an Indo-European language, and much of the percentage that doesn’t rapidly adopted the bronze, horses, and chariots to fight off those that do.
Horses and wagons transform tribal warfare from constant spats with the closely related neighboring villages, which probably had little genetic effect after the first tens of thousands of years of it, to serious and fast migration and massed warfare, which is what the bronze age is known for.
Yes, I should have scrolled down before responding to William.
Horses increased the range of contact both for war and trade.
I’ve seen people say that something like 40% of men being killed off was the norm for tribal warfare but the steppe nomad expansion pumped those numbers up quite a bit. Certainly as impactful as disease.