A "tusk-free" gene typically found in 2-5% of male Asian elephants is now showing up in 5-10 percent of elephants in China, according to a Beijing zoologist who has been studying the creatures since 1999. "This decrease in the number of elephants born with tusks shows the poaching pressure for ivory on the animal," Zhang Li says. Link (Thanks, Sphinx)
Reader Comment: Chris Zable says,
Poaching, or any other environmental selection pressure, does not cause DNA to mutate. Environmental forces such as poaching favor particular gene variants (in this instance, apparently a gene already present in the gene pool, not a new mutation), causing them to become more prevalent. Hoping for more cool bio postings!
Dan says,
It's fun to note that people used to believe in inheriting acquired traits, aka Lamarckism (named for a French biologist who championed the idea: Link. It was disproven by August Weismann, who cut off the tails of rats successively for many generations, but discovered that their children still had tails (what do you know?) Link. Nonetheless, my mother says she remembers, going to school in the fifties, being told that because of the automobile humans would eventually be born without legs. Wwouldn't we still need them to press the accelerator? Weird!
And John Williams says:
I hate to disagree with your commentors. Enough violence is done to the elephant while harvesting the tusks that the elephant often dies even if the poacher does not take the short-cut of killing the animal first.
Dead animals don't have sex and elephants without tusks aren't targeted by ivory hunters. This means that the tuskless elephants have greater opportunity at reproduction (less competion from dead tusked
elephants) and father more elephants (they're around longer to have more sex), thus increasing the prevalence of the tuskless mutation. So it's not Lamarkism, just basic natural selection at work.
Mark Federman, Chief Strategist for the McLuhan Program in Culture and Technology at the University of Toronto, says:
Interestingly, one of the McLuhan Program in Culture and Technology's lecture series this year was on "Evolutionary Biology as a Medium," at which this very phenomenon was explored through human history. The link for the write-up of that lecture is
here: Link
