This is it. The evolution of Homo sapiens is complete, says British geneticist Steve Jones—not because we’ve reached some pinnacle of perfection, but because we’ve run ourselves into an evolutionary dead end. Jones argues that the structures of contemporary society have jammed the three main drivers of evolution: natural selection, mutations, and random change.
He spoke yesterday at the
1) Fewer early deaths. If everyone lives to reproductive maturity (in the developed world, nearly 98 percent of people survive to the age of 21), natural selection can do little work.
2) Fewer elderly fathers. As a man ages, the likelihood of genetic mutations in his sperm increases dramatically. It used to be common for men to father many children with many different women well into old age, but this is less acceptable in today’s society.
3) Too many people. Because of agriculture, there are 10,000 times as many humans as there should be.Small isolated populations allow random change because some genes are accidentally lost. But today’s huge interbreeding global population reduces these random changes.
So there you have it! We’re stuck with what we’ve got, for the rest of human history. Jones may as well have entitled his talk: “The Case for a Few Promiscuous Old Men.”
Jones has been getting a lot of press for his talk but there’s little evidence to back him up. On the contrary, recent genetic studies show humans have been evolving rapidly in the last 5,000 years.
To read more on why Jones’ theories don’t stand up to scrutiny, check out the buzz over on ScienceBlogs here, here and here.
Image: flickr/whalt
