Grow Your Brain With Facebook

Michael Bell
August 27, 2014

There have been many academic studies linking increased brain size in mammals to social complexity: it doesn't seem very contentious to suggest that dealing with the complex behaviours of up to 150 group members would require more brain cells than solitary life. Or at least it seems likely to have been true until the state began to take over management of social relationships: someone should study whether couch potatoes have smaller brains than professional carers. But there have been relatively few rigorous attempt to correlate brain size with particular social behaviours.

Now a team in the University of Colombia's Department of Zoology has carried out research, published in the Journal of Ecology and Evolution, which demonstrates a clear correlation between brain size and the need to care for offspring. OK, it's in stickleback fish, and they're not even mammals, but what seems particularly convincing is that it's the males that have larger brains than the females, and it's the males who do the caring in that particular species. Of course this will be unsurprising to human females, who have long known that looking after their children requires more mental capacity than going down to the pub and watching football, but it does offer an escape route from female domination for those males who are prepared to search for their inner carers.

Well, enough frivolity. In the study, 'Reversed brain size sexual dimorphism accompanies loss of parental care in white sticklebacks', researchers compared regular male sticklebacks to male white sticklebacks, which do not tend to their offspring, and found a clear difference in brain size. They found evidence that this change in male behaviour giving up caring for the young occurred at the same time the white stickleback evolved a smaller brain. The white stickleback is a newly-emerged species that only diverged from other sticklebacks 10,000 years ago.

Said lead author Kieran Samuk, a PhD student in UBC's Dept. of Zoology: "This suggests that regular sticklebacks have bigger brains to handle the brain power needed to care for and protect their young. This is one of the first studies to link parental care with brain size."

The association between greater brain size and social complexity is of course demonstrated across many species, not just mammalian. How far back could we go, then in terms of demonstrating a linkage between social (groupish) behaviour and brain size?

Before fish, in general terms, from an evolutionary perspective, came sharks (chondrichthians). They certainly have social behaviours, and there is a wide variety of brain designs and sizes among contemporary sharks. Interesting then, to know if any correlation could be established between shark socializing and their brain size. Then come the invertebrate sea creatures, and another level of difficulty in terms of research. We need submersible robot PhDs, and that is a stretch, currently.



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