Bigger Brains Provide Evolutionary Heads-Up to Females

Bigger brains are only better if they have an evolutionary advantage. Now, scientists have taken a closer look at the brains in fish to answer why investing in a larger brain might provide an evolutionary advantage to compensate for the fact that brain mass is expensive to develop and maintain.

In this latest study, the researchers looked at guppies, which are a species of freshwater aquarium fish. In order to see if brain size influenced survival, they released 4,800 guppies from large- and small-brained selection lines into large, semi-natural streams. These streams also contained a natural predator, called the pike cichlid.

The large-brained females, whose brains were about 12 percent larger than that of the small-brained females, evaded their predators more often. This meant that they had a higher rate of survival. However, the larger brains didn't provide any survival benefit for males since they're more colorful and more conspicuous than females to large predators.

"Our findings support the hypothesis that large brains provide a survival benefit under predation pressure," said Dustin Penn, co-author of the new study, in a news release.

The research also is the first to suggest that groups of fish with large or small brains behave differently in the presence of the predatory cichlid. This behavior should be studied further. In addition, the scientists hope to find out whether or not surviving fish product more offspring.

The findings reveal that when it comes to brains, bigger may just be better-in some cases. That said, further research is needed in order to better understand the details of this phenomenon.

The findings are published in the journal Ecology Letters.

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