Here's a new Just So story that Kipling would be proud of: Many years ago in the distant land of Africa a small troop of human-like primates emerged from the forest and noticed a herd of antelope nearby. "What a delicious dinner," grunted one of the apes. "Let's go get one." Whereupon the hirsute hominid picked up a stick and began running towards the herd.
Fortunately for the primate, the creatures weren't hard to catch. After all, this was a long time ago when animals weren't nearly as fast. And these antelope had never seen a two-legged monkey before and didn't think they were dangerous. At first the antelope just looked at the man with curiosity. Then when they could see that this novel being was coming right for them, they decided to run away. Sadly for them they didn't run fast enough and the man caught up with the oldest (and slowest) animal and beat it with a stick. That night the primates had meat for dinner.
Many years passed and the man-like beings kept chasing after the antelope. After a few generations they started raising children that were faster than normal. This was a promising development. They would be able to catch more antelope. But the antelope started getting faster too and so they had to be content with an escalating status quo.
As generations turned into millennia and millennia turned into a vague infinitude, the apes became humans and the man/antelope relationship became something truly unexpected. It involved vast amounts of time and evolutionary pressure. But the antelope came to run as fast as 50-60 miles an hour over short distances and the men, while not being able to run nearly as fast, could keep running for hours and could eventually run an antelope to the ground out of sheer persistence.
This, of course, is not a true story. Even so, amazing as it might seem, there are many people - including scientists, athletes, and the generally gullible public - that think it is. The whole scenario (with a lot more detail) has come to have a sophisticated name. It's called "persistence hunting". It is the newest evolutionary explanation of why humans are capable of running so fast and for so long.
The latest issue of Outside magazine (May 2011) has a story of a few marathon runners chasing American antelope just to see if it might be possible. Sadly, they failed, but not without coming close enough to make the whole thing seem plausible. Plausible, that is, to people who don't know any better. For in fact, the possibility of this sort of thing really happening is less likely than any of Kipling's famous stories.
For starters, antelope were not slow creatures all those many years ago. Lions, cheetahs, hyenas and their earlier ilk were happily pawing the African plain and were eager to chase any antelope too slow to get away. Even if our physical ancestors did emerge from the African forests, they would never have been fast enough to catch an antelope or have a chance of running one down. Besides, marathon runners are not the human norm. Even after millennia of this so-called evolutionary leg race, an average human being (not to mention somebody in good shape) would have no chance.
But you might argue that marathon runners prove otherwise. This is hardly true. Marathon runners are impressive, no doubt, but they are an example of highly trained individuals, not the average direction of our species. They have merely taken our existing human capabilities and pushed them to a limit. In a natural population this doesn’t happen because being well adapted to a certain place involves an entire suite of characteristics. You can’t over-emphasize one without affecting the others.
An antelope is not just adapted to run fast. It is also well adapted to eat the local plants, to blend into the landscape, to fight disease. If you emphasize just one trait, you sacrifice some of the others. This is one of the clearest lessons we have learned through hundreds of years of breeding plants and animals. This is why our domestic breeds almost never survive (or remain true breeds) when left on their own in the wild.
And besides antelope are not domestic breeds. Neither are the animals that hunt them. Surely we could capture lions and breed them for speed if we really wanted to. Such animals would be faster than the ones chasing wildebeest in the wild. But the truth remains that the changes caused by domestic breeders don't happen in nature - no matter how many of our evolutionary apologists try to convince us otherwise. Our many creative breeding programs (spanning millennia) have never been able to make an organism better able to survive in the natural world.
I don't mean to suggest that natural selection doesn't happen - of course it does. Over time, if there were enough environmental pressures acting upon us, we might become faster runners. But this hardly gets us past the huge gap between an arboreal monkey and the antelope-chasing human. Adaptable we may be. Inevitable products of primate evolution is another thing altogether.
Another point I would like to make is that these Just So stories are human-directed stories, just like all domestic breeding projects are human-directed stories of one kind or another. If there is any evolutionary significance in any of them it is that humans can manipulate nature - that we are capable of altering the Creation. Even a highly trained marathon runner is using his or her God-given agency to literally run against nature - of over-developing one capacity at the expense of others. No other species will do this. It’s easy enough to extrapolate from breeding projects to major evolutionary change but our only real point of departure in this sea of speculation is our given genetic endowment – with its remarkable (and limited) adaptability.
What the real prehistory of mortal man involves is a mystery to us all. And so I suppose that I should be more patient with these evolutionary stories. But when the narrative motivation becomes misanthropy and the meaning of human life becomes a mere reproductive calculation, I object. There are, I believe, reasons for our reason, and obvious clues to our conscience - Darwinian fancies notwithstanding.