Spindle neurons in whales
Convergent evolution is what happens when two genetically distinct species independently evolve the same feature. The vivarium in the lobby of Jordan Hall at Indiana University illustrates convergent evolution (or used to, anyway; I haven’t looked at it in awhile); it contains Old World reptile species on one side and New World species on the other, often strikingly morphologically similar but genetically not related. A recent news story from New Scientist reports on a really nifty case of convergent evolution that involves primates and cetaceans. Whales have recently been found to possess spindle neurons, a particular type of brain cell involved in processing complex social and emotional information. Previously these cells were believed to occur only in us humans and our great ape cousins; it turns out that whales not only have them, but have had them for much longer than we have, and may have them in greater abundance than we do (even after you correct for the greater size of their brains). This is the latest in a string of discoveries about animals that are forcing us to rethink our ideas of our own uniqueness. The social behaviors of whales were a clue that maybe they had social and emotional lives of which we know little, and the discovery that they have spindle neurons indicates that they have some of the same equipment that we use to manage our connections to others. I wish I could believe that this would make it harder for people to hunt them.
