Instant evolution. The influence of the city on human genes: a speculative case

The dominant view in today's evolutionary psychology is that our instincts were stamped into our DNA during the infamous EEA, “The Environment of Evolutionary Adaptedness” (Cosmides & Tooby, Evolutionary psychology: A primer. Santa Barbara: Center for Evolutionary Psychology, University of California, 1997.). This is generally reckoned as a roughly two and a half million-year hunter-gatherer phase that ended before the climax of the last Ice Age. Since then, our genetically preprogrammed heritage has supposedly been locked in stone (or better yet, in an amino acid code). We are, so says the current argument, tribal hunter-gatherers decked out in modern clothes. However a strong case can be made for the possibility that human biology has continued to evolve during the 10,000 years since Jericho's builders erected the first city walls. Genes change far more speedily than most evolutionary psychologists realize. Natural selection has had 400 generations to rework our bodies and our brains since the days when Catal Huyuk, Suberde, and Tepe Yahya joined Jericho's mesh of intercity trade. Four thousand years before the rise of the Sumerian cities of Ur, Uruk, and Kish, Stone Age metropolises from Anatolia to the edges of India were already rich in challenges and opportunities. These urban traps and niches may well have been selectors forming much of what we are today. Homo urbanis has not only arrived, he has long since elbowed Homo tribalis far off to the side.