What lay down us human is one of the most intriguing questions in biology . While it ’s easy to point out the physiological and cognitive differences that break us from our closest anthropoid relatives , these are only the tip of the berg . What scientists are itching to divulge is which bits of DNA are responsible for our unique characteristics — what give us the evolutionary shove that resulted in our success ? scientist could be one stone’s throw closer to in the end teasing out the answer with the discovery of a DNA sequence that , when introduced into black eye , made their brains12 % largerthan those with the same stretching from chimps .
Fascinatingly , despite these striking differences , this episode contains only subtle alteration between humans and chimpanzee . what is more , it does n’t encipher for a protein , but instead controls the activity of other genes . This finding could therefore allow for us with some long sought - after brainstorm into the genetic mechanisms that result to our superior brains . you’re able to read up on the field of study inCurrent Biology .
There ’s no question — our brains are pretty limited . Take theneocortex , for illustration . This relatively new increase to our brainiac , which turn back some 100 billion cellular phone , is the hub of our high genial functions , and it ’s significantlysmallerin other great anthropoid species . Itsexpansion throughout human evolutionunderlies our distinct mental abilities , but its genetic groundwork has been elusive .
Although we may share some95%of our DNA with chimpanzees , our genome contains unique segments , calledhuman quicken regions(HARs ) , which remained mostly unaltered during mammalian evolution but then underwent speedy change after we diverged from chimps . While they do n’t encode protein , scientistssuspectthat these could be responsible for our unambiguously human traits . In special , studies have hinted that HAR sequences which increase verbal expression of sure cistron , so called homo - accelerated regulatoryenhancers(HAREs ) , are potential campaigner , but none had been link to a specific trait before .
To delve deeper , scientist fromDuke Universitybegan comparing the genome of humans and chimps with the hope of finding hare that are both dissimilar between the two species and preponderantly expressed in the mind . Out of 106 candidates , one in particular — HARE5 — stand out because of its near proximity to a gene call Frizzled 8 , which is known to be involved in a pathway crucial for brain development .
The team then append either the human version or the chimp edition , which differ by only16 DNA letter , into mouse embryos , alongside a reporter gene which made tissue turn grim whenever the foil was switching a cistron on . Not only did they find that Frizzled 8 is likely under the control of HARE5 , but embryos with the human DNA snippet also becameblue soonerand over a larger field than those with the chimp version . what is more , human HARE5 have neuronic predecessor mobile phone to separate more , resulting in more brain cells and thus a marked—12%—difference in brain size when compared with chimp HARE5 , and the region affected was the neocortex .
“ What we found is a small-arm of the genetic basis for why we have a bigger brain , ” field of study writer Gregory Wray say in astatement . “ This is probably only one firearm — a piffling part . ”
[ ViaDuke University , Current Biology , ScienceandNational Geographic ]
