Human children are slow growers in comparison to our close animal congenator . We spend aroundtwiceas long in puerility and adolescence as chimp , gibbons and macaque , but scientists never knew why . Many believed that this may have something to with the fact that our brains are so energy athirst that less glucose is available to fuel the ontogenesis of the rest of the consistence , but this has been tricky to prove . Now , a new study conducted byNorthwestern Universityanthropologists has finally found inviolable grounds to support this theory . The work has been published inPNAS .
To recover out how much glucose our genius guzzle from birth to maturity , the researchers used previously gatheredPET and MRIbrain scan data and compare this with body increment rate . PET scan are used to mensurate glucose uptake , whereas MRI scans can set mind volume .
As predicted , theyfoundthat body growth slows when the brain consumes a lot of glucose . Furthermore , the brainiac was retrieve to be hungriest when children are around 4 years old , which coincided with a geological period when eubstance growing was dull . At this time , the brain consumes more than 40 % of the body ’s total get-up-and-go outlay . According to lead authorChristopher Kuzawa , Einstein mobile phone connections “ max out ” at this age because we learn so many unexampled things that are decisive to becoming successful mankind . This means that there are less resources uncommitted for the rest of the body to habituate to facilitate growth of other body parts .
This could avail to explicate why it ’s difficult to approximate a young child ’s years based on their sizing , Kuzawa says . Instead , we use other indicators such as speech and behavior .
Together , these data indicate that human brainiac development involve an strange amount of energy and therefore childhood body growth must slow in lodge to compensate . This lends suffer to the“expensive tissue”hypothesis that was first proposed back in 1995 . However , it was originally thought that pocket-sized digestive systems during puerility were give up up more energy for the brain to habituate .
The researchers would like to take this work forward by seeing if this trade - off of growth happens in nearly related primates such as chimpanzee , butacknowledgethat this data would be difficult to chance upon .
[ ViaNorthwestern University , ScienceandPNAS ]
