When Ramachandran and his student Ed Hubbard discovered that the number area of our brain is right next to the color area, they determined that it could not be a coincidence that the number/color form of synesthesia was by far the most common, and that the two areas of the brain that decipher those two things were practically on top of each other. Cross-wiring, cross-talk between brain sections immediately came to mind.

Next Ramachandran studied different numbering systems with his synesthesiast subjects and discovered something else important. Those who saw colors when shown the number “5” in Indian/Arabic numbers, saw no color when shown the Roman Numeral “V.” The same held true for all color inducing numbers. He was able to conclude from this that it was the shape of the numbers, not their numerical abstract concepts of sequence and ordinality, that evoked the colors. But, there are also synethesiasts who do see color in concepts: to them days of the week, months, and numbers in any language evoke color sensations, and Ramachandran determined that these people are simply cross-wired in different, higher level, sections of their brains.

As part of the scientific process, Ramachandran sought to understand why the genes that cause this cross-wiring in the brain survived through the evolution of the human race. If synesthesia resulted from some evolutionary abnormality or mutation, and was not necessary for the survival of the human species, according to evolutionary science, it should have been a phenomenon that did not survive over time. If synesthesia is useless why did it not just disappear over evolutionary time? Although some now believe that there are genetic mutations, referred to now in biology as "spandrels" (sometimes called "exaptions") that are simply by-products of evolution, and not necessary to our survival, Ramachandran continued to hold that only abnormalities that help us survive as a species become permanently incorporated. (go to p8)