In reading an interesting article in the New York Times (in part because it quotes my colleague Andrew MacDougall), I came upon this statement that caused a bit of a cough.
â€œThereâ€™s no such thing as natural selection,â€ Ziska confides. He is not, he hastens to explain, a creationist. He is merely pointing out that the original 19th-century view of evolution, the one presented by Charles Darwin and Alfred Wallace, is obsolete. Their model presented evolution as a process taking place in a nature independent of human interference. That is almost never the situation today â€” even at sea, where less than 4 percent of the oceans remain unaffected by human activity, according to a recent article in the journal Science. This interference with nature has set the stage for the success of a growing category of weeds, one exemplified by cheatgrass: invasive plant species.
Yes, humans have some impact on a great portion of the globe, but this is nonsense for at least three reasons. One, just because humans are involved does not make something "artificial selection" and therefore disqualify it as natural selection, even within the formulation of Darwin and Wallace which drew a distinction . Artificial selection is the intentional breeding of organisms on the basis of some characteristic (e.g., sleek body shape in dogs or high yield in crops). If we dump waste in the ocean and this creates new selective pressures on marine animals, this hardly counts as artificial selection. From the point of view of the organisms involved, it is simply a change in the environment, and natural selection will then operate as usual. (As a matter of fact, I don't consider "artificial" and "natural" selection to be fundamentally distinct processes anyhow — feel free to discuss in the comment section). Two, we may influence environments generally, but there are, as we speak, gazillions of organisms out there struggling for survival and hunting, parasitising, avoiding, mating with, and otherwise interacting with one another independent of human action. Three, natural selection is still occurring both in human populations and indeed within human bodies (among pathogenic agents, for example).
(Hat tip: John Hawks blog)