How to Become a Whale
Certain Darwinian explanations remind me of a favorite Monthy Python skit, "How To Do It." As a peppy, earnestly grinning host of a mock children's TV program, John Cleese opens up:
Well, last week we showed you how to be a gynaecologist. And this week on "How to Do It" we're going to learn how to play the flute, how to split the atom, how to construct box girder bridges and how to irrigate the Sahara and make vast new areas cultivatable.First, though, Cleese introduces Eric Idle as "Jackie," who will "tell you how to rid the world of all known diseases."
Well, first of all become a doctor and discover a marvelous cure for something, and then, when the medical world really starts to take notice of you, you can jolly well tell them what to do and make sure they get everything right so there'll never be diseases any more.Cleese then picks up a flute: "Now, how to play the flute. Well you blow in one end and move your fingers up and down the outside."
That's if you want to be a flutist. What if you want to be a whale?
Not much harder to do. Despite their slow maturation rates and small populations, raising what might seem insurmountable mathematical hurdles of the sort defined by population genetics, whales succeeded in accumulating all the tens of thousands of wildly prohibitive engineering modifications entailed in the transition from amphibious mammal to fully equipped sea creature. And they did it in just 10 million years (circa 50-40 mya).
Writing for Discover Magazine, Carl Zimmer considers the surprising additional development by which baleen whales acquired a unique food-filtering system -- baleen instead of teeth. In this manner, a blue whale supplies himself with tiny shrimp and the like at some half million calories per gulp.
Zimmer narrates the evolutionary tale whereby the toothed Janjucetus participated in a lineage that gave rise later to the baleen whales. "Only later," Zimmer writes, did "the teeth disappear, and the baleen emerge." Just like that. "Janjucetus makes it possible for us to understand how something as bizarre and complex as a mouth full of baleen evolved."
The most important lesson -- hammered home by study after study of evolutionary transitions -- is that these sorts of things don't evolve overnight. They evolve in a series of steps. Pieces of the system emerge and begin to work together, other pieces become incorporated along the way, and all the pieces take on new jobs. And at each step in the process, the transitional animals have fully working systems of bones and muscles they can use to stay alive.Ever so obligingly, things "disappear." They "emerge." Not "overnight," mind you, but "in a series of steps." They "begin to work together." They "become incorporated." They "take on new jobs." And at every step along they way, it's all got to hang together in the form of a living creature.
Well, whales are known to be a quick study, after all.