If we were invaded by 7-foot humanoids that insisted on putting food on high shelves, would we start to evolve into taller humans? Scientists say possibly, and quite quickly too (from an evolutionary standpoint, that is) — just a thousand years, or 40 generations. That’s a second in the grand scheme of things, really.
Evolution is usually observed taking in thousands, if not millions, of years, but scientists have demonstrated in a study published in the journal Nature that when push comes to shove, evolution kicks in to quickly neutralize threats on the genetic level.
They performed an experiment involving a type of lizard called Carolina anoles that were endemic to the southeastern U.S. and that appeared to have evolved larger footpads in response to the arrival of foreign Cuban anoles, which threatened their territory and food supply. With the larger footpads, Carolina anoles were able to climb higher, avoiding the invaders altogether. In their experiment, they introduced Cuban anoles to areas where Carolina anoles still had regular-sized footpads, and after 15 years (20 generations in lizard terms), the native species had indeed evolved into high-flyers.
Of course, humans are not lizards, so there’s no guaranteeing that we would have the same type of response to a serious threat to our existence. We’ll just have to wait and see.