A fin is a limb is a wing

Carl Zimmer in National Geographic:

Screenhunter_2_13Scientists still have a long way to go in understanding the evolution of complexity, which isn’t surprising since many of life’s devices evolved hundreds of millions of years ago. Nevertheless, new discoveries are revealing the steps by which complex structures developed from simple beginnings. Through it all, scientists keep rediscovering a few key rules. One is that a complex structure can evolve through a series of simpler intermediates. Another is that nature is thrifty, modifying old genes for new uses and even reusing the same genes in new ways, to build something more elaborate.

Sean Carroll, a biologist at the University of Wisconsin–Madison, likens the body-building genes to construction workers. “If you walked past a construction site at 6 p.m. every day, you’d say, Wow, it’s a miracle—the building is building itself. But if you sat there all day and saw the workers and the tools, you’d understand how it was put together. We can now see the workers and the machinery. And the same machinery and workers can build any structure.”

A limb, a feather, or a flower is a marvel, but not a miracle.

More on the evolution of complex structures here.  There’s a nice photo gallery here.  And Carl Zimmer has more about this article at his blog, The Loom, here.