It might make you smarter, but having a bigger brain also means you're likely to have less brawn.
That's according to a new study that looked at the brain size of ten primate species and found those with larger brains have less muscle mass.
The results seem to support a theory put forward in the mid-1990s that brains are able to grow larger by stealing resources from other parts of the body.
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Researchers have found primates with larger brains have reduced muscle mass - supporting the idea human brains got bigger by stealing resources from other parts of the body (stock)
The research, reported in New Scientist, was undertaken by Magdalena Muchlinkski at the University of North Texas in Fort Worth.
She looked at cadavers of primate species that died of natural causes.
'Primates, when compared to other animals, have very little muscle,' Dr Muchlinkski told New Scientist.
'What I am seeing now is larger-brained primates have less muscle.'
Researchers looked at a range of species including the 130g Philippine tarsier and the crab-eating macaque, which weighs several kilograms.
A kilogram of brain tissue needs around 240 kilocalories each day to function at full capacity.
'We collected body mass, muscle mass, and biopsied four muscles from each specimen for histological procedures', researchers wrote in the paper published in Wiley.
'Results show that larger brained primates have less muscle and fewer Type I fibres than primates with smaller brains. '
Type I fibres - also known as slow twitch muscles - are used in sustained activities, like running for a long time.
However, these results are still preliminary and experts say a more complete analysis that includes chimps, gorillas and humans, will be published in the next year or so.
Researchers looked at a range of species including the 130g Philippine tarsier and the crab-eating macaque (pictured), which weighs several kilograms
The expensive tissue hypothesis (ETH), which was first put forward in the 1990s, suggests our selfish brains are prioritised when we have to think fast and work hard at the same time.
Researchers believe that a kilogram of brain tissue needs around 240 kilocalories each day to function at full capacity.
Our ability to allocate more glucose to the brain could have helped our species survive and thrive by becoming quick thinkers, experts believe.
The ETH theory has previously been disputed. For example in 2011 researchers from the University of Zurich questioned the theory animals with big brains really had smaller guts.
Now, researchers led by Magdalena Muchlinkski at the University of North Texas in Fort Worth have explored the theory by looking at ten cadavers of primate species.