Threespine stickleback fish are somewhat unusual parents in the fish world - it's the fathers that take care of their young, not the mothers. It turns out that the males also have comparatively larger brains than the females, a team of Canadian biologists report.
Bigger brains work in the fishes' favor when trying to handle the extra neural load of caring for their bunch of fry, according to the so-called "parental brain hypothesis." The demands a parent faces are more complex than living solo, the line of thought goes, and this translates to larger brains, the authors report in the journal of Ecology and Evolution. (A stickleback's fatherly noggin is, on average, 23 percent heavier than a female's.)
Researchers at the University of British Columbia compared the brains and behaviors of the male common sticklebacks to those of white sticklebacks, a closely related species that doesn't have the same paternal instincts. The white stickleback brains, it turns out, are smaller than the common sticklebacks - and the scientists believe this is linked to the difference in the way they raise babies.