We mustn’t forget that those individuals [early humans] were also hunter-gatherers. They worked extremely hard every day to get a living.
- A typical hunter-gatherer has to walk between nine and 15 kilometers a day.
- A typical female might walk 9 kilometers a day,
- a typical male hunter-gatherer might walk 15 kilometers a day, and that’s every single day.
- That’s day-in, day-out, there’s no weekend, there’s no retirement, and you do that for your whole life. It’s about the distance if you walk from Washington, DC to LA every year.
That’s how much walking hunter-gatherers did every single year.In addition, they’re constantly digging, they’re climbing trees, and they’re using their bodies intensely. I would argue that cognition was an extremely important factor in human evolution, along with language, theory of mind — all those cognitive developments that make us so sophisticated. But they weren’t a triumph of cognition over brute force; it was a combination. It was not brains over brawn, it was brains plus brawn, and that made possible the hunter-gatherer way of life.
What hunter-gatherers really do is they use division of labor, they have intense cooperation, they have intense social interactions, and they have group memory. All of those behaviors enable hunter-gatherers to interact in ways such that they can increase the rate at which they can acquire energy and have offspring at a higher rate than chimpanzees. It’s a very energetically intensive way of life that’s made possible by a combination of extraordinary intelligence, inventiveness, creativity, language, but also daily physical exercise.
Until extremely recently, you couldn’t live, you couldn’t survive as a human being without being an endurance athlete. Not just hunting and gathering requires athleticism but also being a farmer. Subsistence farmers have to work extremely hard. Until the invention of industrialized machinery, farmers had to work even harder than hunter-gatherers, often spending many thousands of calories a day. They have to dig ditches and throw vast quantities of hay into bales and they have to schlepp stuff all over the place. Farmers had to work brutally difficult, hard, exhausting lives. It wasn’t until, again, the invention of new technologies such as domesticating animals or even more recently machinery such as the internal combustion engine, that farmers were able to live non-grueling lives.
It’s only in the last 100 years, in fact maybe for many people the last 20, 30, 40, 50 years, that human beings have been able to lead extremely sedentary lives without any physical activity.
…Human brains got bigger and that’s a major effect on their heads, but your brain is actually the same size as a brain of a Neanderthal. Actually, it’s a little bit smaller than a Neanderthal’s, and our brains are only a little bit larger than a late Homo erectus. So what’s really different about our heads is not the size of our brains, it’s really other aspects of our heads.
The most important difference is the size of our face. Humans are profoundly different from every other hominin, which is a species more closely related to humans than to chimps. Our difference from other hominins is primarily the size and position of our face. What we’ve done in our recent evolution is we’ve shrunk our face and we’ve retracted it. Our face is now underneath our brains rather than sticking in front of our brains. That’s why we don’t have big brow ridges, and that’s why our tongues and mouths are small, which causes our larynx to be low and changes the shape of the vocal tract.
Professor of Human Evolutionary Biology, Harvard University – http://edge.org/conversation/-brains-plus-brawn