Summary: According to researchers, wild cat brains don’t necessarily respond to the same evolutionary pressures as primates.
Source: Michigan State University.
The brains of wild cats don’t necessarily respond to the same evolutionary pressures as those of their fellow mammals, humans and primates, indicates a surprising new study led by a Michigan State University neuroscientist.
Arguably, the fact that people and monkeys have particularly large frontal lobes is linked to their social nature. But cheetahs are also social creatures and their frontal lobes are relatively small. And leopards are solitary beasts, yet their frontal lobes are actually enlarged.
So what gives? Sharleen Sakai, lead investigator of the National Science Foundation-funded research, said the findings suggest that multiple factors beyond sociality may influence brain anatomy in carnivores.
“Studying feline brain evolution has been a bit like herding cats,” said Sakai, MSU professor of psychology and neuroscience. “Our findings suggest the factors that drive brain evolution in wild cats are likely to differ from selection pressures identified in primate brain evolution.”
Sakai and colleagues examined 75 wild feline skulls, representing 13 species, obtained from museum collections, including those at MSU. The researchers 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.
Sakai’s lab is interested in uncovering the factors that influence the evolution of the carnivore brain. One explanation for large brains in humans and primates is the effect of sociality. The idea is that dealing with social relationships is more demanding than living alone and results in bigger brains, especially a bigger frontal cortex.
“We wanted to know if this idea, called the ‘social brain’ hypothesis, applied to other social mammals, especially carnivores and, in particular, wild cats,” Sakai said.
Of the 13 wild feline species examined, 11 are solitary and two – lions and cheetahs – are social.
Here are some of the key findings of the research:
*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 said. “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 study, published online in the journal Frontiers in Neuroanatomy, was co-authored by MSU researchers Ani Hristova, Elise Yoon and Barbara Lundrigan; and Bradley Arasznov of Minnesota State University.
Source: Andy Henion – Michigan State University
Image Source: This NeuroscienceNews.com image is adapted from the Michigan State University press release.
Original Research: Full open access research for “Big Cat Coalitions: A Comparative Analysis of Regional Brain Volumes in Felidae” by Sharleen T. Sakai, Bradley M. Arsznov, Ani E. Hristova, Elise J. Yoon and Barbara L. Lundrigan in Frontiers in Neuroanatomy. Published online October 20 2016 doi:10.3389/fnana.2016.00099
[cbtabs][cbtab title=”MLA”]Michigan State University. “Wild Cat Brains: An Evolutionary Curveball.” NeuroscienceNews. NeuroscienceNews, 1 November 2016.
<https://neurosciencenews.com/evolution-wild-cat-brains-5401/>.[/cbtab][cbtab title=”APA”]Michigan State University. (2016, November 1). Wild Cat Brains: An Evolutionary Curveball. NeuroscienceNews. Retrieved November 1, 2016 from https://neurosciencenews.com/evolution-wild-cat-brains-5401/[/cbtab][cbtab title=”Chicago”]Michigan State University. “Wild Cat Brains: An Evolutionary Curveball.” https://neurosciencenews.com/evolution-wild-cat-brains-5401/ (accessed November 1, 2016).[/cbtab][/cbtabs]
Big Cat Coalitions: A Comparative Analysis of Regional Brain Volumes in Felidae
Broad-based species comparisons across mammalian orders suggest a number of factors that might influence the evolution of large brains. However, the relationship between these factors and total and regional brain size remains unclear. This study investigated the relationship between relative brain size and regional brain volumes and sociality in 13 felid species in hopes of revealing relationships that are not detected in more inclusive comparative studies. In addition, a more detailed analysis was conducted of four focal species: lions (Panthera leo), leopards (Panthera pardus), cougars (Puma concolor), and cheetahs (Acinonyx jubatus). These species differ markedly in sociality and behavioral flexibility, factors hypothesized to contribute to increased relative brain size and/or frontal cortex size. Lions are the only truly social species, living in prides. Although cheetahs are largely solitary, males often form small groups. Both leopards and cougars are solitary. Of the four species, leopards exhibit the most behavioral flexibility, readily adapting to changing circumstances. Regional brain volumes were analyzed using computed tomography. Skulls (n = 75) were scanned to create three-dimensional virtual endocasts, and regional brain volumes were measured using either sulcal or bony landmarks obtained from the endocasts or skulls. Phylogenetic least squares regression analyses found that sociality does not correspond with larger relative brain size in these species. However, the sociality/solitary variable significantly predicted anterior cerebrum (AC) volume, a region that includes frontal cortex. This latter finding is despite the fact that the two social species in our sample, lions and cheetahs, possess the largest and smallest relative AC volumes, respectively. Additionally, an ANOVA comparing regional brain volumes in four focal species revealed that lions and leopards, while not significantly different from one another, have relatively larger AC volumes than are found in cheetahs or cougars. Further, female lions possess a significantly larger AC volume than conspecific males; female lion values were also larger than those of the other three species (regardless of sex). These results may reflect greater complexity in a female lion’s social world, but additional studies are necessary. These data suggest that within family comparisons may reveal variations not easily detected by broad comparative analyses.
“Big Cat Coalitions: A Comparative Analysis of Regional Brain Volumes in Felidae” by Sharleen T. Sakai, Bradley M. Arsznov, Ani E. Hristova, Elise J. Yoon and Barbara L. Lundrigan in Frontiers in Neuroanatomy. Published online October 20 2016 doi:10.3389/fnana.2016.00099