Humans developed language as a means of communicating with other tribe members. Language is one of the most important, if not THE most important, reason humans are so successful as a species. It enables us not only to communicate immediate information (e.g. there is a lion in that direction, don't go there) but also form and communicate intricate ideas (e.g. myths, religions). Yuval Hariri in his massively interesting book "Sapiens" talks about how what he calls "fiction" (i.e. stories we humans tell each other) enabled homo sapiens to co-operate in massive numbers (much more than the Dunbar limit of 150) and made us such a successful species. Language was critical in all of that. I believe the advent of language was what gave the biggest boost to cultural evolution in humans. Humans are the only species that significantly evolve culturally as well as naturally. Cultural evolution is exponentially faster than natural evolution - we homo sapiens effectively ...
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