Vilayanur S. Ramachandran, one of today’s most famous neuroscientists, has long studied synesthesia—a phenomenon known for a century yet often overlooked, characterized by the crossing of the senses, such as hearing colors or sensing sounds. Other scientists have long avoided synesthesia, considering it a mistake or an unimportant trifle. But what is the reality?
Through several sophisticated experiments, Ramachandran has proven that synesthesia truly exists. For example, synesthetes who see numbers as colors are demonstrably able to distinguish twos among a group of fives much faster than ordinary people, for whom the digits blur together. Synesthesia is thus not an illusion, but an unusual ability possessed by those who experience it.
Ramachandran even put forward the bold theory that synesthesia is not merely a metaphorical crossing of the senses, but that it is actually caused by a physical crossing of nerve pathways. Sensations intended for one area of the brain are “accidentally” processed by another area, which interprets them as a different modality—much like opening a musical composition in a text file on a computer: the music suddenly becomes text.
Ramachandran’s theory of synesthesia, however, goes far beyond simply explaining the phenomenon: he uses it to explain the existence of metaphors and—ultimately—language as well. Humans are born with a vast number of neural connections that allow them to adapt well to their environment. In early childhood, the connections we use frequently are strengthened—while the others fade away. Synesthesia may then occur due to the genetically determined persistence of certain neural connections that would otherwise have been doomed to disappear in ordinary people—for example, those linking colors and sounds.
But how is it possible that a seemingly useless gene, which is responsible for that “meaningless” neural connection, has survived through natural selection to this day? According to Ramachandran’s theory of language origin through “gradual synesthetic layering,” it is precisely this question that links the seemingly simple and unimportant phenomenon of synesthesia to metaphors and language. This crossover is apparently evolutionarily advantageous, and to some extent, we all possess it!
We all have the sensory inputs of our individual senses at least somewhat interconnected—and it is precisely these connections that underlie our capacity for abstraction and our understanding of metaphors. We can associate “sharp sound,” “sharp shape,” or “sharp taste,” even though the word “sharp” has a completely different meaning in each case. Ramachandran has demonstrated that these connections are not culturally determined but are innate—and he attributes them precisely to these neural cross-connections.
He even argues that this very ability was a necessary condition for the emergence of human language. After all, at its inception, there must have been some foundation common to all humans—a universally understandable association of certain sounds with objects in the surrounding world. Ramachandran sees this in a similar neural crossover, which in this case involves motor areas.
According to him, the very beginnings of human speech were marked by subtle cross-connections, as if people named sharp objects with sharp sounds and blunt objects with blunt sounds. It is precisely such a small detail that can mark the beginning of an evolutionary process that subsequently leads to enormous changes; the giraffe’s neck did not develop all at once, but gradually, thanks to continuous elongation caused by the slight advantage of a few extra centimeters when foraging for food.
The argument may not be 100% convincing, and the author of this article does not presume to convince readers of that. In any case, however, it offers a great example of a potential explanation for social science phenomena through evolutionary (neuro)biology. And that is precisely what Ramachandran attempts to do in his book *A Brief Journey Through Human Consciousness*, the Czech translation of which is just being published.
