What makes humans different from our evolutionary cousins, the great apes? Walking upright and big brains are the top differences. When we think of the evolution of mankind, those two things are often regarded as happening together, but it wasn't quite so. Paleoanthropologist Jeremy DeSilva explains that walking upright came first, not because we were smart, but because the trees we lived in died out.
“March of Progress” was an illustration done by a Russian artist, Rudolph Zallinger, in a 1965 Time-Life book called Early Man. It’s this beautiful foldout that shows ancient apes down on all fours, and it has them slowly rising up to modern humans. At the time, with the fossils we had, you could create a narrative like that. But in the last half century we’ve made so many amazing discoveries that show the human family tree is much more diverse. The pace of evolutionary change is quite different and it turns out that upright walking is the earliest of these evolutionary changes. The earliest bipeds on the ground were evolving from things that were upright to begin with in trees. Really all that happened was an ecological change. These hominins were living in environments that had fewer and fewer trees. To continue to get from point A to point B to get your fruit and other food resources, you already are pre-adapted for an upright posture and moving on two legs. In that case, bipedalism wouldn’t be a new locomotion, it’d be an old locomotion. It was just in a new setting on the ground, rather than in trees.
Walking upright put our ancestors into quite a vulnerable position, but it was only later that proto-humans developed large and flexible brains to deal with the situation. Meanwhile, we had to be adaptable and use the environment we had by becoming cooperative and omnivorous. Read how that came about in a fascinating interview with DeSilva at Nautilus. -via Damn Interesting
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