A study of differences between the human and chimp genomes has identified a gene associated with neural growth in the cerebral cortex – the part of the brain involved in processing thoughts and learning – as having undergone “accelerated evolutionary change”.

Katherine Pollard and colleagues at the University of California Santa Cruz, US, suggest that the fast-changing gene may help explain the dramatic expansion of this part of the brain during the evolution of humans.
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There are only two changes in the 118 letters of DNA code that make up HAR1 between the genomes of chimps and chickens. But chimps and humans are 18 letter-changes apart. And those mutations occurred in just five million years, as we evolved from our shared ancestor.