Yawning – you might never have thought about it while you were trying to stifle that yawn in your meeting this morning, but it’s something that the majority of the animal world does.

Which is why scientists were able to conduct this latest study and deduce that the length of your yawn says a lot about the size of your brain.

The study, published in Biology Letters, showed a correlation between yawn duration and brain weight, as well the number of cortical neurons i.e. the number of cells in the cerebral cortex, the brain’s largest region.

They found that mammals with larger brains yawned longer.

Lead researcher Andrew Gallup looked at the brain weight data for 29 mammals and then sent his team of researchers out to watch the animals yawn, record the duration and coming up with an average for each type of mammal.

They mostly did this by watching YouTube videos of animals yawning, which, to be honest, sounds like the kind of study we want to be a part of.

Researchers studied 205 individual yawns from mammals including possums, African elephants and humans.

They discovered that humans yawned for an average length of seven seconds, with chimpanzees coming in at five seconds.

Mice yawned for one and a half seconds on average.

It’s long been suggested that yawning is a way of getting more oxygen into the body, but this study mentions another hypothesis – that yawning is a way of cooling down the brain, in two different ways.

Firstly, with an influx of cold air from outside, and secondly, because we constrict then relax our facial muscles during a yawn, which sends more warm blood around the skull, allowing heat to escape.

Thus, a larger brain requires a longer yawn.

This also means next someone at work passively aggressively asks if they’re ‘keeping you awake’ when you yawn, you can shut them down with a swift, ‘Nah mate, just cooling down my cortex’.

You might find this hard to believe, but researchers couldn’t find as many animal yawning videos on the internet as they needed, so their conclusion isn’t as solid as they were hoping for.

However, they say their results are a good pointer for further research on the subject i.e. watching animals yawn in the flesh, as well as looking within species to see if yawn length dictates mental skills.

Obviously brain size doesn’t equate to intelligence, but it would be interesting to see how yawn length correlates with brain variants within humans, and they hope to do this in the future.