How did hands evolve? Answer is behind you

Study shows hands were likely taken in part from our nether region

- CARL ZIMMER

ABOUT 360 MILLION years ago, our fishy ancestors moved from water to land.Along the way, their fins turned into feet, with toes.

And hundreds of millions of years later, the front pair evolved into hands.To understand this profound evolutionary transformation, scientists have spent decades studying the fossils of extinct fish that sported limb-like fins. They have also compared the embryos of modern-day fish and land vertebrates to understand how their fins and limbs develop.

Now the precise DNA-editing technology known as CRISPR is letting scientists reconstruct this ancient evolutionary change in molecular detail. It turns out that hands and feet were not the products of new genes doing new things. Rather, through natural selection, pieces of old genetic recipes for ancient body parts were cobbled together into new combinations. “It’s much easier than if you had to build from scratch,” said Aurélie Hintermann, a postdoctoral researcher at the Stowers Institute for Medical Research, in Kansas City, Mo.