Hunting in the News: Messing with Evolution

The second hunting story for today comes from Newsweek--"It's Survival of the Weak and Scrawny: Researchers see 'evolution in reverse' as hunters kill off prized animals with the biggest antlers and pelts."

Hunting is often celebrated as playing a grand role in conservation of species--it is argued that if hunters didn't want to (and weren't allowed to) kill certain animals, no one would have any interest in protecting those species or the species' habitat. A species as a whole gets to live only because we let hunters have the fun of killing some of the members of the species, the argument goes. But given that hunters seek out the biggest, best, and strongest of animals (unlike nonhuman predators, who hunt for sustenance rather than bragging rights and so kill the weakest, oldest, and easiest to catch), what researchers are now telling us shouldn't be surprising: humans are messing up nonhuman animals' evolution.

Selective hunting—picking out individuals with the best horns or antlers, or the largest piece of hide—works in reverse: the evolutionary loser is not the small and defenseless, but the biggest and best-equipped to win mates or fend off attackers.

When hunting is severe enough to outstrip other threats to survival, the unsought, middling individuals make out better than the alpha animals, and the species changes. "Survival of the fittest" is still the rule, but the "fit" begin to look unlike what you might expect. And looks aren't the only things changing: behavior adapts too, from how hunted animals act to how they reproduce. There's nothing wrong with a species getting molded over time by new kinds of risk. But some experts believe problems arise when these changes make no evolutionary sense. . . .

"Losers" tend not to be very good breeders, meaning that this demographic shift ultimately threatens the viability of a species. Researchers also worry that the surviving animals are left with a narrower gene pool. In highly controlled environments, a species with frighteningly little genetic diversity can persist—think of the extremes of domesticated animals like thoroughbred horses or commercial chickens—but in real ecosystems changes are unpredictable. Artificially selecting animals in the wild—in effect, breeding them—is "a very risky game," says Columbia's Melnick. "It's highly likely to result in the end of a species."

Thanks to Erik Marcus for the alert.