He therefore also believed that synesthesia had been necessary for our survival rather than a useless evolutionary mutation. Without a gene survival explanation, though, Ramachandran could not prove his theory of cross-talking senses or of the necessity of synesthesia for human survival.

Ramachandran noted that the gene-based proof of synesthesia is based on the fact that it has been proven to be passed from generation to generation. He also knew, and this is where the artist’s brain comes in, that artists (like our Amy Beach) are much more likely to have synesthesia. Artists, poets and novelists are seven times more likely to have synesthesia. Ramachandran reasoned that what these people all have in common is that they are all “. . . very good at metaphor – linking seemingly unrelated concepts in their brain.”

Some of my favorite metaphors:
• A computer’s “desktop” and “trash can” are both metaphors for “real” office equipment - the theory behind their invented use being that computer users would be more comfortable using familiar office tools.
• “Hope is the thing with feathers that perches in the soul, and sings the tunes without the words, and never stops at all.” – Emily Dickenson
• out out brief candle - William Shakespeare
• The fog comes on little cat feet. It sits looking over harbor and city on silent haunches and then moves on. - Carl Sandburg
• Shall I compare thee to a summer's day? - William Shakespeare

Cross-talk between two close sections of the brain result in one form of synesthesia; cross-talk in another two close sections result in a different form of synesthesia. But cross-talk between more numerous and more distant sections of the brain make a person more prone to metaphor because more concepts are linked in the mind’s map. go to p9