#1201 - William von Hippel

Joe Rogan (0:01)

All right, here we go.

Four, three, two, hello Bill. What's going on, man?

William von Hippel (0:10)

I am very excited to be here.

Joe Rogan (0:11)

I'm excited to have you here. Excellent. The Social Leap.

William von Hippel (0:14)

Yes.

Joe Rogan (0:14)

What's the Social Leap?

William von Hippel (0:16)

I'll tell you all about it.

Joe Rogan (0:17)

Please do.

William von Hippel (0:18)

Okay. So, the story that I want to tell is basically how we got here, how we became human. And so, that story begins about six or seven million years ago, when our ancestors left the rainforest.

And so, the question is, why would they leave and how would they survive once they left? And that's what the Social Leap is. So, it takes a second to get it all out there, okay? Yeah. So, here's the story.

So, if you look back about seven million years, our ancestors and chimps, we had a common ancestor at about that point in time, six or seven million years ago. And that common ancestor, we don't know exactly what it looked like, but from all we can tell, it was awfully close to today's chimps.

And so, if you look at chimps today, you can get a pretty good sense of what life was like then. And chimps today are really interesting. They're basically at the top of the food chain in the rainforest. They're super fast up in the trees, super athletic, and because they travel in groups, even amazing tree climbers like leopards won't try to attack them in trees. It's just they're too dangerous, too fast. But if you look at a chimp on the ground, it can't even lock its knees. It's this kind of cute little stumbled in a long thing. And then the question is, why would an animal that runs a show in the canopy leave the rainforest for the savanna and then how would it survive once it did that?

And that's the story of this book and then how that manifests itself to where we are today. So really my goal, I'm a psychologist. I want to understand why we are the way we are. And so in trying to figure that out, I said, well, let's take a look back all the way to our common ancestors and see some of the key events and how they might have had an influence on how we are today. So the first question is, why would we leave the trees, right? Here we are, we're dominant position, we're food on the ground, why would we ever take that risk? And the basic story there is the great African Rift Valley. I'm not sure if you're familiar with it at all, but basically it runs down from up at the Red Sea down to the coast of Mozambique. And you can think of it like a geographic zipper.

All the world sits on these tectonic plates, and sometimes they crash into each other, like how India is smashing into Asia and creates the Himalayas. Sometimes they literally tear apart, and Africa is tearing apart at the Great African Rift Valley. So that plate that has Somalia and Ethiopia, Tanzania, Kenya, that's moving off to the lower right. The rest of Africa is moving off to the upper left.

And I got no idea why. It's been going on for quite a while. But one of the consequences of that is that the East Africa is starting to rise up slowly, bit by bit, and when it rises up, the rainforest dry out. And so basically what you have is a situation where our ancestors were on the East side of that rift valley, and it started to dry out, and now they're in a situation where they've got this great lifestyle, they're a dominant position, but now they're forced out onto the ground increasingly more and more, because there's more and more ground and less and less rainforest. And so how do they survive that? What do they do in order to make that work?

Joe Rogan (3:10)

And this is a... what period of time is this? How many millions of years ago?

William von Hippel (3:14)

Six or seven.

Joe Rogan (3:15)

Six or seven. Does this coincide with the... when was the jump of the human brain size?

William von Hippel (3:21)

We'll get to that. So it's a super interesting question about why that happened as well. So basically, if you track us across the next three million years, how did our ancestors survive when they're basically chimpanzees on the open savanna? And you can get a hint of how they did it, because there's one chimpanzee group that does live on the savanna in Senegal, and they show some differences between themselves and other chimps. They travel in slightly larger groups. They share more nicely with each other, which is interesting. That's kind of a human trait as well. And they also avoid open space. Like, they're just kind of trying to stay near the trees as much as possible. And so, and if you look at other, they're not apes, but other primates that are on the savanna, like savanna baboons, they're only monkeys, so they're not as sharp as chimpanzees are. But they have a similar strategy, large groups to try to protect themselves and lots of eyes to look out for predators. And they do fine on the savanna. And so what I suspect happened is for the first few million years, basically what you've got is this chimp-like animal that's kind of skirt in the edge of the savanna, nowhere near the top dominant position they used to be and just kind of noodling around. And that takes, I suspect that takes us for about the first three, three and a half million years. And if you look at who we are then, we're Australopithecus afarensis. So it's, if you looked at one of them, you'd think it belongs in a zoo. It looks almost like a chimpanzee. And so a chimp brain, in answer to the first part of your question, is about 380 grams.