That men allegedly have larger brains than women is a controversial issue. However, males are clearly the winners when it comes to brain size, at least for some fish, according to a study published in a recent issue of the online journal PLoS ONE.
Weighing the brains of 58 male and 61 female Threespine sticklebacks (Gasterosteus aculeatus) from Lake Mývatn in Iceland, Alexander Kotrschal and coauthors found that the males had significantly heavier brains (by an average of 23%) than females.
The authors hypothesise that the larger brain in male sticklebacks is the result of the cognitively demanding challenges, such as an elaborate courtship display, the construction of an ornate nest and a male-only parental care system, faced by them.
However, they acknowledged that their limited sampling does not allow them to make more general conclusions.
For more information, see the paper: Kotrschal, A, K Räsänen, BK Kristjánsson, M Senn and N Kolm (2012) Extreme sexual brain size dimorphism in sticklebacks: a consequence of the cognitive challenges of sex and parenting? PLoS ONE 7, e30055. doi:10.1371/journal.pone.0030055
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