New research reveals that as humans continue to alter the habitats of animals, we may also be impacting the way they evolve, the New York Times reports, as animals are developing larger brains to adapt to their ever-changing environments.
University of Minnesota biologist, Emilie C. Snell-Rood, studied a collection of small mammal skulls kept at the Bell Museum of Natural History at the University of Minnesota, looking closely at 10 species of small mammals, including mice, shrews, bats, and gophers, all collected from as far back as 100 years ago. With the help of undergraduate student Naomi Wick, Snell-Rood measured the dimensions of the mammals' cranial cavities, which made it possible to estimate the sizes of their brains.
"It is thought that behaviorally flexible species will be able to cope with novel and rapidly changing environments associated with human activity," Snell-Rood and Wick wrote in the abstract of their study. "We predicted that urban populations would show greater cranial capacity than rural populations and that cranial capacity would increase over time in urban populations. Based on relevant theory, we also predicted that species capable of rapid population growth would show more pronounced evolutionary responses."
Indeed, the brains of the white-footed mouse and the meadow vole that lived in cities or suburbs were 6 percent larger than those of their rural counterparts. In rural parts of Minnesota, Snell-Rood and Wick discovered that two species of shrew and two species of bats also experienced an increase in brain size, perhaps due to their homes being turned into farmland.
"We're changing rural populations, too," Dr. Snell-Rood told the New York Times, explaining that bats may have to travel farther to find food and a place to roost as the trees nearest their caves are cut down.
As humans continue to develop former forests into cities and farms, animals must adapt, and adapt fairly quickly, to survive in their ever-changing environments.
"Our results provide partial support for the hypothesis that urban environments select for increased behavioral plasticity, although this selection may be most pronounced early during the urban colonization process," the researchers wrote.
"I think the results are exciting and deserving of much follow-up work," Jason Munshi-South, an evolutionary biologist at Fordham University who was not involved in the research, said to the Times.
