I just finished reading Carl Zimmer‘s very fine book Evolution: The Triumph of an Idea; which is a great introduction to the topic and covers a lot of ground, from Darwin’s life aboard the Beagle to host-bacteria arms races (stop having antibiotics, people!) to man-caused mass extinctions to whales with legs to the invention of language.
After talking about cognitive offloading last week, and about how we’re as dumb as cavemen, I found it curious to stumble upon this text in the book:
The artifacts that [early] humans left behind speak to a profound shift in the way humans saw themselves and the world. And that shift may have given them a competitive edge. “Something happened about 50,000 years ago,” explains Klein. “It happened in Africa. These people who already looked quite modern became behaviorally modern. They developed new kinds of artifacts, new ways of hunting and gathering, that allowed them to support much larger populations.”
Researchers can only speculate for now about what brought the shift about. Some have proposed that the creative revolution was purely a matter of culture. Anatomically modern humans in Africa experienced some change – perhaps a population boom – that forced their society to cross some kind of threshold. Under these new conditions, people invented modern tools and art. “Cro-Magnons were perfectly capable of going to the moon neurologically, but they didn’t because they weren’t in a social context where the conditions were right,” says White. “There was no challenge to provoke that kind of invention.”
Whatever the reason for the appearance of modern behaviour, slightly after humans started tinkering with artifacts and tools, they spread out of Africa and replaced (or perhaps wiped out through competition or diseases) Neanderthals and Homo erectus around the world. “In an evolutionary flash, every major continent except for Antarctica was home to Homo sapiens. What had once been a minor subspecies of chimp, an exile from the forests, had taken over the world.”
(Note: If you’re thinking of buying the book, be aware that the 2006 paperback edition does not come with those lavish illustrations the Amazon reviews mention. It’s still worth it, but I can only imagine how much better the original -and sold out- 2001 edition is, since this is a subject that really benefits from images.)