Why do humans blush? We're the only animal that does. Darwin called blushing "the most peculiar and the most human of all the expressions," but was unable to explain its purpose.
Some theories:
http://www.newscientist.com/article/mg20327200.700-10-mysteries-of-you-blushing.html
Mark Twain had an answer:
ReplyDelete"Humans are the only animals that blush, or need to."
It was said to get a laugh of course, but he may have had a point.
John