Joined: Sep. 2006
Isn't this romantic?
|February 12, 2008, 9:26 pm |
A Tyrannical Romance
If Charles Darwin were alive today, he’d be turning 199: like Abraham Lincoln, he was born on Feb. 12 1809.
I considered observing their joint birthday with a discussion of slave making in ants, but rejected that idea in favor of another. For later this week is another Big Day: the feast of St. Valentine. With apologies to Lincoln, I’ve decided to hold a Darwin-Valentine celebration by revealing one of my more tyrannical romantic fantasies.
I should say, by way of preamble, that Darwin contributed far more to biology than the “Origin of Species,” in which he laid out how evolution by natural selection works, and the evidence for it at the time. He also wrote (and this list is not complete): a treatise on the formation of coral reefs, which is still held to be correct; a landmark work on carnivorous plants; a definitive treatise on barnacles, extinct and extant; a study of how earthworms plow and aerate soil; and a fascinating speculation on the evolution of emotion in humans and other animals.
And that’s not all. One of his other major works, “The Descent of Man, and Selection in Relation to Sex,” includes a huge compilation of the sexual decorations and displays of animals, from the jaws of stag-beetles to the tail of the Argus pheasant, which far exceeds that of the peacock in absurd magnificence. From his study of all this, Darwin began to elucidate systematic patterns and principles of the evolution of courtship and sexual behavior. In particular, he developed the concept of sexual selection, which is the idea that cumbersome ornaments like big tails can evolve, even if they make the bearer less likely to survive, if the opposite sex (usually the female) finds them attractive.
In doing so, he founded one of the most important and successful branches of evolutionary research. We now have a robust understanding of how sexual pressures — the pressures to find, impress, and seduce a mate — influence the evolution of males and females. So much so that if you tell me a fact, such as the average size difference between males and females in a species, or the proportion of a male’s body taken up by his testes, I can tell you what the mating system is likely to be. For example, where males are much bigger than females, fighting between males has been important — which often means that the biggest males maintain a harem. If testes are relatively large, females probably have sex with several males in the course of a single breeding episode.
These forces are so reliable that, if only we could determine the sex of dinosaur fossils, we could begin to infer their mating habits. But alas. Unless the animal died while heavy with eggs, as one oviraptor obligingly did, determining the sex of a dinosaur is close to impossible. At one point, it was thought that the shape of a particular bone at the base of the tail might indicate sex; but a recent analysis has shown it does not. Now the best guesses come from subtle differences in structure of the bone in the hind legs. For the time being, then, fossils are stonily silent about the dinosaurs’ private lives, their methods of wooing, the exuberance of their song-and-dance routines.
Which brings me to my tyrannical fantasy. I want to take a journey 68 million years back in time to see a Tyrannosaurus rex couple mating. What was it like? Did they trumpet and bellow and stamp their feet? Did they thrash their enormous tails? Did he bite her neck in rapture and exude a musky scent? Somehow, I imagine that when two T. rex got it on, the earth shook for miles around.
Which came first: the shimmy, or the hip?
AtBC Poet Laureate
"I happen to think that this prerequisite criterion of empirical evidence is itself not empirical." - Clive
"Damn you. This means a trip to the library. Again." -- fnxtr