Great (Dane) minds don’t think alike

Female and male dogs react differently to the same thing

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Female dogs might have a leg up on males when it comes to detecting the unexpected. In an experiment designed to mess with their furry heads, Fidettes took note of a surprising outcome while Fidos apparently remained oblivious. The results, which will appear in an upcoming Biology Letters , highlight that like humans, animals also have sex differences in how the brain works. In the study, researchers led by Corsin Müller of the University of Vienna tested 50 pet dogs, including poodles, Australian shepherds, golden retrievers and mutts. The team designed an experiment to test whether the dogs would notice a ball that inexplicably grew or shrank. In some trials, for instance, a tennis ball-sized ball would roll behind a screen, and after a short wait, a larger ball would appear on the other side. (Young babies don’t seem to notice this violation of how the world normally works, but start to react to the weirdness during the first year of life.) When the ball was a different size after emerging from the screen, female dogs stared at it longer than they did a ball of the expected size, an indication to Müller and his colleagues that the females had noticed something amiss. In contrast, male dogs looked at the surprising ball and the ball of the expected size for similar amounts of time. Though the researchers weren’t expecting to find a sex difference, the results aren’t too surprising, says Müller. “For humans, there is plenty of evidence for all kinds of differences between men and women in cognitive processes,” he says. “So if you think of it from that angle, you’d actually expect to find sex differences in quite a few places, and it’s not all that surprising anymore.” So far, the researchers can’t tell if males really don’t perceive the difference, or do detect it but don’t care, Müller says. Whether a dog had been neutered didn’t seem to make a difference in the experiment, suggesting that the brain differences behind the effect were established early in the dogs’ development and were not a result of sex hormones circulating in adult dogs at the time of the test. Researchers don’t know how or why this sex difference exists. Müller and his colleagues don’t think strong evolutionary pressure on a dog ancestor has a role. Male and female canines didn’t have very different lifestyles that would have led to this cognitive performance difference, he says. But neuroscientist Timothy Koscik of the University of Iowa points out that females need to effectively nurture offspring, and that might have provided very strong pressure to set up this behavioral difference. “If you’re going to draw any line between males and females,” he says, “that’s probably the most obvious and most meaningful one to draw.”

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A male mutt sits by his owner and watches as a large ball seems to turn into a smaller one.
Credit: C. Müller et al./Biology Letters 2011

Laura Sanders is the neuroscience writer. She holds a Ph.D. in molecular biology from the University of Southern California.

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