Genetic research is telling us that human evolution is proceeding at a much faster pace than previously thought
While some are still mired in the debate about evolution actually being real, scientists continue to find the clues that are solving some of the most elementary mysteries of who we are as humans and where we’re going. Nancy Shute in US World News Report tells us that human evolution is proceeding at a faster pace than any time in our short history. A few excerpts from this excellent article:
Until recently, anthropologists thought that human evolution had slowed down. But last December, Hawks reported that it has actually accelerated 100-fold in the past 5,000 to 10,000 years. He figured that out by comparing chunks of DNA among 269 people from around the world. Over time, DNA accumulates random mutations, just as the front of a white T-shirt tends to accumulate spots. The bigger the chunks of DNA without random spots, the more recently it had been minted. Using this system, Hawks concluded that recent genetic changes account for about 7 percent of the human genome. Much of the increase, he says, has been fueled by the growth of the world’s population, which has expanded by a factor of 1,000 over the past 10,000 years. Having more people increases the odds of mutations.
At the same time, the human genome has been scrambling to adapt to a rapidly changing world—11,000 years ago, nobody farmed, nobody milked domesticated animals, and nobody lived in a city. People with a mutation that aided survival were more likely to thrive, reproduce, and pass that mutation along to offspring. For example, the capacity to digest lactose, the sugar in milk, has become common only over the past 3,000 years. Now, about 95 percent of the people in northern Germany have the mutation, which also popped up independently among the Masai in Africa and the Lapps in Finland. Hawks says: “This is really rapid evolution.”
Mutations serve as triggers for change.
The human brain, which has evolved into a cognitive machine unique in the world, is likely to change even more in the future. Our niche in nature, says Stephen Pinker, an experimental psychologist at Harvard University who studies the evolution of language and the mind, is the “cognitive niche.” In research published last year, Wray identified genes that control glucose metabolism in the brain as among those most recently evolved. Those changes may have been essential to fueling the human brain’s growth to a size twice that of our nearest cousin, the chimpanzee. “If you make a big brain, it’s an energy hog,” Wray says. “It’s like putting a V-8 engine in a tiny little car.” It could also help explain why chimpanzees don’t get diabetes, while humans do.
Shure also touches upon HIV:
Some people are genetically more resistant to the HIV virus, for instance, and that trait should become more common in the future, as those people are more likely to survive and have children who are resistant.
A good complement to Shure’s comment on genes and HIV in Africa can be found in The Economist article: AIDS – DARC Continent. The article tackles the specifics of why Africans are more succeptible to contracting HIV and why protection against Malaria (resulting from a previous genetic mutation) might be the reason.