Jeremy Shere

Evolution is something happens over millions of years, right? Slowly, over eons of time, primates evolve into hominids, hominids in proto-humans, proto-humans into modern homo sapiens.

But evolution doesn’t always unfold at such a crawling pace. Take, for example, the case of several Italian wall lizards left on a small island off the coast of Croatia in the early 1970s. According to a recent piece in National Geographic, just a few decades later, the lizards have evolved a new gut capable of digesting plants, bigger heads and a harder bite.

Here’s what seems to have happened …

After being introduced to the island, within a few years the wall lizards took over and wiped out the native lizard populations. How exactly this happened is a bit mysterious, since the native lizards subsisted on plants, while the invading lizards weren’t built for vegetarian life. Maybe the wall lizards ate insects or other small animals. Maybe they ate the native lizards. In any case, at some point the new lizards fond themselves on an island where the main item on the menu was vegetation. So over several generations, the wall lizards evolved special mechanisms in their guts to digest plants. They also evolved larger heads and a harder bite–all within about 30 generations.

The NG article quotes a biologist, Andrew Hendry, as saying that it’s not clear whether the lizards’ adaptations were genetic in origin or a “plastic response to the environment.” I’m not sure what this phrase means. Isn’t evolution a “response” to the environment? What does the word “plastic” imply.

Anyhow, at the very least, the case of the wall lizards very strongly suggests that, under the right conditions, evolution can occur at a very rapid pace. Given the current climate of skepticism about evolution and the promotion of pseudo-scientific theories like intelligent design, stories like this are all the more important.

By the way, check out this review in the NY Times of the anti-Darwin “documentary” “Expelled.” I took the movie to task in this space a few months back. The review corroborates my argument.