They say you should never judge a book by its cover, but - as it turns out - sometimes external appearances can give away a little more than we've been led to believe.
According to a new study of more than 100,000 people, babies with bigger heads are more likely to be successful later on in life. And the science behind it is actually pretty simple: bigger heads = bigger brains = better cognitive function. Yes, it might sound a little too good to be true - but the research is there to back it up.
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The study, titled 'Shared genetic aetiology between cognitive functions and physical and mental health in UK Biobank' (bit of a mouthful!) examined links between physical, mental, and cognitive aspects of hundreds of thousands of individuals, and found some promising evidence of correlation in the mix.
Professor Ian Deary, one of the study's authors from the University of Edinburgh, said: "In addition to there being shared genetic influences between cognitive skills and some physical and mental health states, the study also found that cognitive skills share genetic influences with brain size, body shape and educational attainments."
According to the findings, "highly significant associations were observed between the cognitive test scores in the UK Biobank sample and many polygenic profile scores, including ... intracranial volume, infant head circumference and childhood cognitive ability." The study later adds: "These results demonstrate substantial shared genetic aetiology between brain size, cognitive ability and educational attainment."
In other words, intelligence is directly correlated with brain size, as well as overall head size in infancy.
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The results claim that anyone with a head of a circumference of 31.75cm to 35.56cm is smarter than average - but, of course, not everybody fits the rule. Likewise, just as there are some people with larger heads who aren't above average intelligence, there are also some outliers with smaller heads who happen to be super brainy.
With their newfound discoveries, the researchers plan to look further into predictors of health and intelligence.
"With so many findings, it has not been possible fully to discuss their implications," the study concluded. "For example, the genetic associations between infant head circumference and intracranial volume with educational attainment and verbal-numerical reasoning are important in themselves, as are many other cognitive–mental health and cognitive–physical health associations."
What we do know already, however, is that having a big head as a kid is nothing to be embarrassed or ashamed about. In fact, it's an indicator of future success - and therefore a pretty great thing to have.