Longer Yawns Mean Bigger Brains, Researchers Say

If this article makes you yawn, thank us.

Scientists report that bigger yawns promote brain activity and growth in each species. Psychologist Andrew Gallup from the State University of New York and his team say the average duration of a yawn predicts the species' brain weight and number of cortical neurons.

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"Because the magnitude of this response likely corresponds to the degree of neurophysiological change, we hypothesized that interspecies variation in yawn duration would correlate with underlying neurological differences. Using openly accessible data, we show that both the mean and variance in yawn duration are robust predictors of mammalian brain weight and cortical neuron number (ρ-values > 0.9). Consistent with these effects, primates tend to have longer and more variable yawn durations compared with other mammals," Gallup said in his report.

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The report drew its conclusions from 109 separate examinations from 19 different species, everything ranging from humans, capuchin monkeys, African elephants and mice.

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Yawning's Effect on the Brain

In 2007, Gallup presented a theory that opening our jaws and taking in air cools our brains as a kind of restart. Yawning simply increases blood flow to the brain by replacing warmed blood with cooler blood from your heart, and the heat is exhaled into surrounding air.

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"The fact that yawning is constrained to a thermal window of ambient temperature provides unique and compelling support in favor of this theory. Heretofore, no existing alternative hypothesis of yawning can explain these results, which have important implications for understanding the potential functional role of this behavior, both physiologically and socially, in humans and other animals," Gallup said.

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One question still remains: If you yawn longer than someone else, does that mean you have a larger brain? Gallup said that "remains an empirical question," only to be answered with continued research.

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For more detailed information, you can read the full research here and download it as a PDF file as well.

Via: Biology Letters, Frontiers in Neurocience

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