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Remember When Elephants Had Tusks?
Boing Boing links to an interesting story today. If an antibiotic kills 95% of a germ species, but 5% bear a gene for resistance, indiscriminate use of it will result in a surviving line of entirely resistant germs. But on a slightly larger scale, genetically tusk-free elephants are gaining ground relative to their tusked brethren, says one study, thanks to a nasty antibiotic called poaching. If elephants don't have the decency to go extinct, maybe they'll just hang around to tusklessly remind our grandchildren where billiard balls originally came from, and to invite us to ponder what the last poacher was thinking as he shot the last tusked elephant.
On CNN the other day, I heard this referred to as "survival of the fittest," which was one of the dumbest things I had heard in weeks. The anchor implied that because tuskless elephants used to be 5% of the elephant population and now they're 8%, this means that more elephants are being born with the tuskless gene, which could be completely false. If I have 100 elephants, 5 of them tuskless, and I kill 37 of the tusked elephants, 8% of the elephants are now tuskless - Darwin it ain't.
I have to strongly object to your terminology. Evolution is not an entity or process which can be "forced" into anything. It is simply an observation about what happens in the world.
"Selective pressure" is an incredibly loaded term which anthropomorphizes what's really happening. In this case, what is happening with the elephants is that the ones with tusks are being killed off, and the ones without tusks are not (and it's not any more complicated than that). There is nothing putting "pressure" on the elephants to lose their tusks. The mutations are random and happen without respect to environmental changes. It is the environment which makes some of these mutations more or less favorable but it is not the cause of those mutations.
Suppose you wanted to "force" humans to evolve gills, like fish. Suppose that you did this by rounding up everybody who did not have gills, and drowning them. Do you think this procedure has any chance in hell of causing humans to start growing gills? The reason why not, is that the sort of mutation that could cause that is extremely complex and almost infinitely unlikely. But in the case of the elephants, the tuskless phenotype was present even before the advent of modern hunting.
Evolution has no will, no path, no agenda, no nothing. It can't be forced, pressured, coerced, etc.
Tuskless elephants giving birth to tusked offspring (if they do), means nothing: it could be that the trait is recessive.
The post you refered to made a critical error: the author assumed that the percentage mentioned is the percentage of living elephants without tusks. It's not. It's the percentage of elephants being born without tusks. So culling will have no impact on that figure.In the parks of Kenya, poachers go heavily armed, obviously to kill elephants, but also to defend against wardens, who shoot to kill on sight.
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