Bigger brains can make animals, well, brainier, but that boost in brain size and ability comes at a price. That's according to new evidence reported on January 3rd in Current Biology, a Cell Press publication, in which researchers artificially selected guppies for large and small brain sizes.
The findings lend support to the notion that bigger brains and increased cognitive ability do go together, a topic that has been a matter of considerable debate in recent years, said Niclas Kolm of Uppsala University in Sweden. They also represent some of the first convincing evidence that large brains are expensive, evolutionarily speaking.
"We provide the first experimental evidence that evolving a larger brain really is costly in terms of both gut investment and, more importantly, reproductive output," Kolm said.
Together, the findings strongly support the idea that relative brain sizes among species are shaped through a balance between selection for increased cognitive ability and the costs of a big brain.
The results in guppies have important implications for us humans. After all, one of the most distinctive features of the human brain is its large size relative to the rest of the body.
"The human brain only makes up 2 percent of our total body mass but stands for 20 percent of our total energy demand," Kolm said. "It is a remarkably costly organ energetically."
But support for the so-called "expensive-tissue hypothesis"—that there is a trade-off between the brain and the energy demands of other organs and reproduction—came only from comparative studies among species and were correlative in nature.
In the new study, Kolm's team took a different, within-species approach. They selected live-bearing guppies for large and small brains relative to the size of their bodies. Under that strong selection pressure, they found that brain size could evolve "remarkably quickly."
After selection, large-brained guppies outscored their smaller-brained peers in a test of numerical learning. With more energy devoted to brain-building, brainy fish—males especially—did have smaller guts. They also left fewer offspring to the next generation.
Those effects were observed despite the fact that the fish were supplied with an abundance of food. The researchers say they are curious to see what will happen in future experiments with fish in a more competitive, semi-natural environment including limited resources and predators.
The findings lead Kolm and his colleagues to suggest that the relatively small family sizes of humans and other primates, not to mention dolphins and whales, might have helped to make our big brains possible.
Cell Press: http://www.cellpress.com
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
What’s scarier than a tyrannosaur? Three tyrannosaurs.
The timing of when a girl reaches puberty is controlled by hundreds of genes, say scientists.
After the world's most expensive salvage operation, the ill-fated Costa Concordia is being floated back to Genoa, where it will be chopped up for scrap metal
Hijacking how neurons of nematode worms are wired is the first step in an approach that could revolutionise our understanding of brains and consciousness
A Beverly Hills auction house has an unusual fossil for sale. It's not an ancient animal. It's something an ancient animal left behind — and it's very, very long.
Dog owners don't doubt that their pooch has feelings. But scientists aren't so sure. An experiment found that dogs act upset, dare we say jealous, when their owners ignore them for a stuffed animal.
Princeton University’s annual science art contest shines a light on the research world, adding a video element this year
Using mitochondrial replacement therapy to create embryos with DNA from three people could have serious consequences Continue reading...
Chinese and Australian scientists find pandas migrate long distances to maintain a balanced diet which helps them breed
On the morning of March 15, 2000, 17 beaked whales stranded themselves on beaches in the northern Bahamas. It was an terrible and extraordinary event: beaked whales are the world's deepest-diving mammals, and these creatures had spent most of their lives in deep undersea canyons.