Also in this week's column:

• Are women who are forty, fat and fair more likely to get gallstones?
• When is seeing not seeing?
• Is the human skull made up of one bone or two?

Why is the human face hairless?

Asked by Tom Sherwood of Worthington, Minnesota

Most other mammals have hairy faces. So why are we humans an exception? In fact, most other higher order primates have facial hair patterns at least a little similar to our own. For instance, take chimpanzees.

Comparing the face of a chimpanzee to that of a recent U.S. President... Be that as it may. In both non-human higher order primates and humans, hair gathers around the face in a rather similar manner. It comes in varying degrees down the brow, around the ears, down alongside the cheeks, and forms a beard - at least in half of us.

The evolutionary adaptive virtue of a hairless face appears to be that it enables the clearer and easier sending and receiving of social messages through facial expressions. This was and is important for survival. As humans evolved into the complex creatures we are, and with a complex social organization to match complete with dominance hierarchies, etc., “reading” faces well makes a lot of sense.

We need to be able to discern more about the intentions of our fellow humans. We gain valuable clues as to the likely behaviors of others by watching their faces. We discover which individuals to trust, to fear, to comfort, to scold, and so on. We would be at a distinct disadvantage without the ability to “read” a face. Hairlessness makes it all so much better and easier to do so.

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au

Related stories

• Do we really need a daily shower or bath to stay healthy? (17 February 2007)
• What ever happened to tuberculosis? (3 February 2007)
• Why do some people have three nipples? (13 January 2007)
• Is there such a thing as frigidity? (23 December 2006)
• How the 'true blue' political maverick gave the senate to the donkeys (9 December 2006)
• Can you really see the Great Wall of China from the Moon? (1 December 2006)
• Will sweets really rot your teeth? (24 November 2006)
• Do humans have a compass in their nose? (17 November 2006)
• What is a Cro-Magnon man? (10 November 2006)
• Does TV watching in childhood trigger autism? (3 November 2006)