Joseph Henrich — Humans defeated smarter species with cultural evolution

**Dwarkesh Patel** (0:00)
Today, I have the pleasure of chatting with Joseph Henrich, who is a professor of human evolutionary biology at Harvard University, and an author of two of my favorite books, The Weirdest People in the World, and before that, The Secret of Our Success. And I was just mentioning to you that I remember reading this, I don't know, many, many years ago when I was in college, and at the time, I didn't think I would get a chance to ask you questions about it. I recently had your colleague David Reich on, and we were discussing certain things in the record of human history where he said like, look, you eventually just got to have Joseph Henrich on and ask him these questions because he's the one who would know. So let me ask you one of the questions which I was super intrigued by, which he raised and we didn't come up to an answer to. So one of the things he's discovered through his genetic evidence is that 70,000 years ago, across Eurasia, there's so many different human species from the Denisovans to the Neanderthals to the Hobbits. And then apparently, there's this one group which was potentially the size of 1,000 to 10,000 people in the Near East, which subsequently explodes, and now everybody who's descended from Eurasia descends from this one group. And so I guess the question is like, what happened? What did they figure out?

**Joseph Henrich** (1:17)
Yeah, so a typical assumption when people think about this, if you put it in the Paleolithic, they assume that it has to do with some kind of genetic changes.
Now, Reich's lab, there's no obviously big changes in the DNA, so it's a little bit of a puzzle. Neanderthals, for example, had larger brains. And in primates, larger brains usually goes along with more computational abilities, more ability to solve problems. So the expanding variant out of the Middle East, out of Africa, might have actually been less able at an individual level to process information. But if you look back over the more recent period of human history, you can see that it's a story of expansions of different populations. So, for example, in Africa, we have the Bantu expansion about 5,000 years ago, which actually eliminates a whole bunch of hunter-gatherer populations that previously existed in Africa. We have the remnant populations in parts of the Congo, in the Kalahari and the Hadza, for example, in Tanzania. If you look at the Austronesian expansion, so that's the peopling of the Pacific. That was the expansion of one group of people at the expense of others. And of course, the Neolithic expansion into Europe is another example. So really, human history is a story of these different expansions. And it could be that this expansion across Eurasia, which then led to interbreeding, so we know it's the same species. Humans interbred with Denisovans and Neanderthals, as well as probably other species. There's a ghost species in there. This could be just institutional changes. So if you have institutions, for example, that interconnect your population, you can maintain more sophisticated technology. And some paleoanthropologists, for example, have speculated, with some evidence, that the expanding populations had projectile weapons. So, bows and arrows. And humans have periodically gained and lost bows and arrows in different parts of the world. So in Australia, for example, bows and arrows are never invented. In the New World, when the Arrivals populations probably didn't have bows and arrows, but then later developed bows and arrows.

**Dwarkesh Patel** (3:11)
It's also really interesting how some technologies you would just think of as extremely... I don't know what the word is, but the New World, like not having the wheel or something, I guess it kind of makes sense with no domesticated animals, but again, it's like such a...

**Joseph Henrich** (3:27)
Right, although the New World, everybody has dogs and you can pull carts with dogs. So I've never really bought that. And of course, you can use llamas in the New World to pull carts as well. People do that today.

**Dwarkesh Patel** (3:37)
Yeah, so what's your explanation for why there's no wheels in the New World?

**Joseph Henrich** (3:41)
So there are wheels on Mayan carts or Mayan toys. My explanation is just the collective brain. So almost every single first invention of something big that we think is important for humans was invented in Eurasia. And Eurasia, as Jared Diamond famously pointed out, building on other people's work, it's the largest continent by far. It has the biggest population. It's also oriented along an east-west axis, which allows ideas and people to more easily flow. And there's a belt, which the historian Anne Morris calls the lucky latitudes, which runs from basically southern China all the way through to the Mediterranean. And ideas are just flowing back and forth there.