A research group argues that a species’ number of neurons, rather than brain volume, should serve as indicator of cognitive capacity when studying brain evolution, but some experts voice doubts.
The fish species is separated from mammals by hundreds of millions of years of evolution, yet its seemingly primitive brain can handle many of the same elaborate visual tasks.
Guppies with experimentally shrunken brains produced more offspring than guppies bred for larger noggins, confirming a long suspected tradeoff of bigger brains.