"Wired for Culture, " a remarkable new book by Mark Pagel, an American evolutionary biologist based in England, sets out to explain this peculiar human property of fragmenting into mutually uncomprehending cultural groups.
"It is a debate that is often conducted as a shouting match between two mutually uncomprehending camps, each unable or unwilling to accept that there may be any validity at all in the other's point of view, " he said.