Saturday, January 17, 2009

The Big One That Got Away

Heard an interesting discussion on NPR's Science Friday yesterday:
Research published this week in the Proceedings of the National Academy of Sciences says that predation by humans through hunting, fishing, and gathering has had significant influences on the rate of evolutionary change in a wide variety of species. Traits such as body size and first reproductive age shift significantly in species that are 'harvested,' the authors say.

"Fishing regulations often prescribe the taking of larger fish, and the same often applies to hunting regulations," said Chris Darimont, one of the authors of the study. "Hunters are instructed not to take smaller animals or those with smaller horns. This is counter to patterns of natural predation, and now we're seeing the consequences of this management." Darimont and colleagues found that human predation accelerated the rate of observable trait changes in a species by 300 percent above the pace observed within purely natural systems, and 50 percent above that of systems subject to other human influences, such as pollution.

So basically, by removing the biggest animals from the population (of fish, Bighorn Sheep, etc.), we are speeding up evolution within those populations. It could be said we are managing the breeding programs of these animals through artificial means and causing them to select for unnatural traits. Which is kinda what has gotten us into the genetic mess we are in with purebred dogs. Granted there are very different methods and motivations at work but there is a similarity to my mind. I am not against hunting game or breeding dogs but I do think we can do both more responsibly, with an eye for the big picture. Because focusing on a set of trophy horns for the wall or winning a ribbon at a dog show seems to be leading us down the wrong path toward a dead end future.

Listen to the podcast of yesterday's Science Friday show here.


Caveat said...

Makes sense, especially when you consider that more than hunting is affecting natural populations.

I always feel sad when they show a huge fish that some trog has caught and killed. That fish lived a long time, probably produced thousands of new fish and now he's come to an ignominious end. I feel the same way about any mature, obvious survivor regardless of species. Those genes will be missed.

Thing is, when you keep taking the little ones in huge numbers, you also seriously affect future populations, since it takes awhile to reach breeding size in many species.

And no, I'm not anti-hunting or anti-fishing in principle, I just don't think someone's insecurities about what's in their pants should be assuaged in that way if it has negative implications for the world.

And you're spot on about selection.

YesBiscuit! said...

I think the idea is to have some sense of balance. But of course that's always difficult to achieve and as it stands now, you can actually be fined by the fish and game warden if you don't "throw the little ones back". So it's not even an option for many hunters/fishermen. One example from the show: commercial fishing boats are designed to haul up the largest fish. Re-outfitting them for something different would come with a HUGE price tag and we'd need laws changed in order to even initiate it. No small obstacles.