A study of wild cats seems to contradict the idea that social relationships are more demanding than living alone and result in a bigger brain, especially a bigger frontal cortex.
“Our findings suggest the factors that drive brain evolution in wild cats are likely to differ from selection pressures identified in primate brain evolution,” says Sharleen Sakai, a professor of psychology and neuroscience at Michigan State University who led the study.
Researchers examined 75 wild feline skulls, representing 13 species, obtained from museum collections. They used computed tomography (CT) scans and sophisticated software to digitally “fill in” the areas where the brains would have been. From that process, they determined brain volume.
“We wanted to know if this idea, called the ‘social brain’ hypothesis, applied to other social mammals, especially carnivores and, in particular, wild cats,” adds Sakai.
Of the 13 wild feline species examined, 11 are solitary and two—lions and cheetahs—are social.
Here’s what they found
- Surprisingly, overall brain size did not differ, on average, between the social and solitary species of wild cats. But the part of the brain that includes the frontal cortex did differ between the two species.
- The female lion had the largest frontal cortex. Female lions are highly social, working together to protect and feed their young, hunt large prey, and defend their territory. In contrast, males may live alone and may be dominant in a pride for only a few years. The larger frontal cortex in females compared to male lions and the other wild cats may reflect the lionesses’ demands of processing social information necessary for life in the pride.
- The social cheetahs, in contrast, had the smallest overall brains and the smallest frontal cortex of the wild cats. Small brains weigh less and require less energy, factors that might contribute to the cheetah’s remarkable running speeds. “Cheetah brain anatomy is distinctive and differs from other wild cats,” Sakai says. “The size and shape of its brain may be a consequence of its unusual skull shape, an adaptation for high-speed pursuits.”
- Leopards’ frontal lobes were relatively large. Although the leopard is solitary, it is noted for its flexibility and adaptability—behaviors associated with enhanced brain processing and larger brain size in other species.
The findings appear online in the journal Frontiers in Neuroanatomy. Researchers from Minnesota State University collaborated on the project, which the National Science Foundation funded.
Source: Michigan State University