Mark Pagel addresses the conundrum posed by variegated cultures. Culture -- what we have that monkey's don't (according to a witty formula quoted by Pagel) -- both unites us and divides us. In Wired for Culture, Pagel attempts an evolutionary account for the existence of cultures. His inquiries commence with the mad multiplicity of languages. Language is the prime instrument of cultural transmission and the strongest marker of cultural identity. Yet the intra-group facilitation of communication provided by distinct languages are foreclosed to outsiders. Our languages seal us off from one another.
Human adaptability to the widest range of niches offers only a partial explanation for the multitude of cultures. New Guinea sports more than 800 different languages within a very small territory -- here mutual unintelligibility seems to be the point. Language operates both to permit and prevent understanding; both these characteristics are necessary. The value of a closed system of communication has long been recognized. Tradesmen, criminals and academics use argot to separate themselves and to keep secrets.
Pagel makes an evolutionary case for the multiplicity of languages; language serves as an identifier of group membership. This is culture's darker role: defining group boundaries. Pagel sees language and other cultural institutions functioning to set limits for altruism. Humans are social -- but only to a degree. We are a species that engages in magnificent cooperation -- yet are capable of inflicting harm on a scale not found in any other species.