Posts Tagged ‘Snell-Rood’

Humans are enabling some animals to evolve larger brains

August 23, 2013

As humans implement artificial selection on themselves – a process and a force for evolution operating much faster than natural selection could  – they are also changing the environment for evolutionary selection in which many animals live. Some of these species are enormously successful in adapting to their new environments while others cannot cope with the change. The changes are so profound that the evolutionary trajectories of these species are changing. It could be that the “urbansisation” of these species has led some species to follow an evolutionary path which includes increasing brain size in their new, man-made surroundings. Carl Zimmer writes in the New York Times:

Are We Making Animal Brains Bigger? 

Evolutionary biologists have come to recognize humans as a tremendous evolutionary force. In hospitals, we drive the evolution of resistant bacteria by giving patients antibiotics. In the oceans, we drive the evolution of small-bodied fish by catching the big ones.

In a new study, a University of Minnesota biologist, Emilie C. Snell-Rood, offers evidence suggesting we may be driving evolution in a more surprising way. As we alter the places where animals live, we may be fueling the evolution of bigger brains.

Dr. Snell-Rood bases her conclusion on a collection of mammal skulls kept at the Bell Museum of Natural History at the University of Minnesota. Dr. Snell-Rood picked out 10 species to study, including mice, shrews, bats and gophers. She selected dozens of individual skulls that were collected as far back as a century ago. An undergraduate student named Naomi Wick measured the dimensions of the skulls, making it possible to estimate the size of their brains.

Two important results emerged from their research. In two species — the white-footed mouse and the meadow vole — the brains of animals from cities or suburbs were about 6 percent bigger than the brains of animals collected from farms or other rural areas. Dr. Snell-Rood concludes that when these species moved to cities and towns, their brains became significantly bigger.

…..  Studies by other scientists have linked better learning in animals with bigger brains. In January, for example, researchers at Uppsala University in Sweden described an experiment in which they bred guppies for larger brain sizes. The big-brained fish scored better on learning tests than their small-brained cousins.

Animals colonizing cities and towns have to learn how to find food in buildings and other places their ancestors hadn’t encountered. ..


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