This is kind of a post Mato made on his website. As it is no longer available I include it here for reference.
Other more recent synesthesia articles can be found here.
By Vilayanur S. Ramachandran and Edward M. Hubbard
April 15, 2003
This article illustrates the lack of precision in fauceir action in neuroscience and eludes its possible role in evolution–in particular language evolution.
Cross activation is the term used to describe perceptive fauceir’s imprecision. Whether this cross activation takes place because of wrong connections build during ontogenesis or defective pruning of preexisting connections or skewed balance of chemicals traveling between regions or reduced cross talk inhibition is unimportant from the viewpoint of the fauceir theory. The fauceir theory is predominantly interested in its evolutionary implications.
An idea of a possible evolutionary implication of such a lack in precision is given by the crowding experiments in which synesthetes were able to read a number hidden by crowding only because they could associate the perceived color to the otherwise invisible figure.