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5 December 2013 11:26 am ,
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An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
- About Us
Lifestyles of the Big and Brainy
27 August 1997 8:00 pm
ARNHEM, THE NETHERLANDS--Natural selection can reshape the mammalian brain as well as change its size, a researcher announced here this week at the biennial meeting of the European Society for Evolutionary Biology. Because embryos all follow roughly the same plan as they develop, some biologists had thought that when natural selection favors one part of the brain, the brain would have to enlarge as a whole. But a statistical study of several orders of mammals, from shrews to humans, suggests that evolution can selectively enlarge specific brain structures.
The new result is at odds with one reported two years ago by Barbara Finlay and Richard Darlington of Cornell University. They analyzed the size of brain regions of 131 species of primates, bats, and insectivores, and found that brain size could predict the proportions of the specific regions, like the neocortex. This suggested that the evolution of the mammalian brain might be constrained by a basic developmental plan.
Willem de Winter, an evolutionary biologist from the University of Western Australia in Perth and his colleague Charles Oxnard reanalyzed the data with different statistical tools. They found "hardly any correlation between size of the brain structures and brain size," says de Winter.
Instead, evolution seems to have tailored the size of individual brain structures to fit animals' lifestyles. For example, the brains of nine species of carnivorous bats have almost the same internal proportions. In brain structure, these bats resemble each other far more closely than they resemble their relatives, despite having evolved separately on four continents over millions of years. "It's because they all share the same hunting strategy," says de Winter, "and so natural selection has shaped their brains in the same way. It's a wonderful example of convergent evolution."
The researchers found similar clusters in other animals that share the same lifestyle, such as primates that use their arms for locomotion. "What's exciting here is to see that different components of the brain have been responding to natural selection in different ways," says evolutionary biologist Kevin Laland of Cambridge University in the United Kingdom.