It continues to baffle me not only how people can say that they don’t “believe” in evolution, but also in the more educated public’s inability to shift the meaning of the term. If you want to argue about whether or not humans descended from a common ancestor of the other great ape species, despite all of the overwhelming evidence, I can grant a shadow of doubt. But the term “evolution” in and of itself is not debatable.
In laboratories all across the world, scientists watch evolution in action on a daily basis. Viruses and bacteria evolve defenses against both our natural immune systems and science’s best attempts to thwart their infections. Guppies can be selected to breed larger brains in just a few generations. Evolution actually happens in the word today; there is no debating that fact.
And if evolution can happen in laboratories, you’d better believe it’s happening in the world around us every single day. Some birds who are adapting to life in an urban setting now have shorter wing spans so that they can avoid assholes in taxis. What other ways might our influence on the natural landscape be pushing species to change in?
One theory postulated by a University of Minnesota evolutionary biologist is that animals might have to get smarter to adapt to human environments. Those with the brain capacity to figure out how to navigate newly build urban settings might be selected for, and as a result, the entire species might move toward a larger brain size. Naturally, Emilie Snell-Rood went to test her theory out.
That’s what scientists do.
Snell-Rood went to the University of Minnesota’s Bell Museum of Natural History and grabbed specimens from 10 small species of mammals indigenous to the area dating back to the early 1900s. The collection included shrews, voles, bats, squirrels, mice, and gophers from all across the Twin Cities metro region. She then measured the size of their cranial capacities and compared them to their descendants out in the world today.
The resulting data wasn’t exactly inspiring. Of all the species tested, only two of the modern day urbanites showed a substantial increase (six percent) in brain size. And, in fact, a few of the species actually showed a decrease in brain size. What’s more, of the two that did show an increase in smarts, it wasn’t a continued climb; it appears as though their skulls grew in size when initially introduced to urbanization but then said, “Meh, screw it, we’re good here.”
So if anything, the evidence supports an importance in smarts to an initially steep learning curve. The introduction to a brand new environment can indeed select for the smartest to survive the change. But once they get the knack for it, the city seems to do to animals exactly what it does to humans: idiocracy.
The paper, “Anthropogenic environments exert variable selection on cranial capacity in mammals,” was published in the Proceedings of the Royal Society B by Snell-Rood and Naomi Wick, an undergraduate at the University of Minnesota, who did the dirty work of actually measuring all of those skulls.