Old Hands and New Fins

The paddlefish is a surreal giant, with a spatula-shaped nose that some scientists believe it uses to sense the electric fields of its prey, which it sucks up like a whale. You might not think of it as an animal that has much to offer in our quest to understand ourselves. But in fact, underneath the glaring differences, paddlefish and humans share some surprising similarities. And those similarities are precious clues to how our distant ancestors evolved hands and feet. Back 400 million years ago, our ancestors swam with fins. The descendants of those early fish split off into two main branches. One became the ray-finned fishes--a group that makes up the vast majority of fish alive today. The other, sometimes called the lobefins, produced many species, but only three lineages of lobefins survive today. One is the coelacanths, which survive in a few isolated spots in the Indian Ocean. ...