Do chimpanzees experience #synesthesia?
Extraordinary evidence generates extraordinary claims. I discuss the remarkable memory skills of chimpanzees tested in the Kyoto Primate Laboratory, and suggest a novel – but deflationary – hypothesis to explain them. Could the chimpanzees, who have been highly trained to learn the sequence of Arabic numerals, have developed number–colour synaesthesia?
It’s just a couple of pages of speculation, but I thought it might interest people here.
It may be objected that synaesthesia is rare in humans (around 4% of adults ). So, if a group of humans were to be put through the same training as the chimpanzees – learning a sequence of arbitrary symbols on a screen – it is unlikely that more than a few would develop colour asso- ciations. Then why should the chimpanzees be any more susceptible than the majority of humans? I do not have a strong answer. But I would point out that, since ex hypothesi no chimpanzees in previous history have experienced synaesthesia, the syndrome will not have been exposed to natural selection. Thus, the reason it occurs may be just that the propensity for this kind of cross- cortical leakage has not been curtailed – as it apparently has been in humans.
Here are some more links about Ayumu: