28th June (UPI) – A larger brain is not always a winning evolutionary strategy. The mountain beaver offers the latest evidence that sometimes it makes sense to sacrifice brain power for other benefits.
Today the mountain beaver Aplodontia rufa spends most of its time in underground tunnels. But recent research suggests that his closest relative lived in trees.
The rodent's 30-million-year-old ancestor also had a smaller body and a larger brain. Over time, fossil evidence indicates that the beaver became nocturnal and reached subterranean layers. The eyesight of the mammal lost importance and the neocortex of the Mountain Bishop shrank.
Although mountain beaver have bigger brains than their relatives, they are much smaller compared to the beaver's increased body size.
"The brain is metabolically expensive, meaning it needs a lot of energy to function," said Ornella Bertrand, a postdoc in the Department of Anthropology at the University of Toronto Scarborough, in a press release. "The parts of the brain that are not critical to survival may have been selected."
Mountain beaver can still climb trees and do so occasionally, but without brain and vision, they are not as powerful as their relatives.
"There seems to be a relationship between tree life ̵
Scientists have previously had a relative decrease in the size of brains in domesticated animals, including dogs, pigs, and chickens, but the phenomenon is rare in wild animals.
Mountain beaver are found in the Pacific Northwest and parts of southern British Columbia. Like their more famous cousins, the North American beaver, mountain beaver eat wood. However, they do not cut down trees or build dams. Instead they chew on small trees and live in underground caves like marmots.
Researchers have detailed their analysis of the mountain beaver's brain in the journal Palaeontology.