HUNTINGTON’S disease is awful. It slowly robs its victims of mobility, wits and emotions. And there is no cure. The idea that it might be the obverse of something good sounds, to say the least, counter-intuitive. Yet that is the contention of a small band of neuroscientists who have been studying it. They suggest the underlying cause of Huntington’s, a strange form of genetic mutation called a triplet-repeat expansion, might also be one of the driving forces behind the expansion of the human brain. Huntington’s, these people suspect, may be a price humanity pays for being clever…

This article first appeared in The Economist on 7 March 2015. To continue reading, click here.