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1.4.8How Long Does Evolution Take? Are We Still Evolving?
Darwinian evolution happens sssssllllllllloooooooooowwwwwwwwlllllllllyyyyyy.
Human brain modules evolved during Palaeolithic times, when our ancestors were hunter-gatherers. Pinker: “The mind is organized into modules or mental organs, each with a specialized design...Their operation was shaped by natural selection to solve the problems of the hunting and gathering life led by our ancestors in most of our evolutionary history.” These adaptations still influence our behaviour and often complicate our lives in an increasingly high-tech social environment. We humans disregard our Stone Age genetic inheritance at our peril.
Are humans still evolving by Darwinian natural selection? There is evidence we are:
- One genetic mutation that regulates brain size (MCPH1) arose 37,000 years ago, and has spread “rapidly” (by slow evolutionary standards).
- Another brain-size-regulating gene (ASPM) emerged in its modern form only about 5,800 years ago.
Still, the overall Darwinian evolutionary change in the short term (over the past few tens of thousands of years) cannot be great, because it takes such a long time for an important adaptation to become encoded in the genome of a species.