Wednesday, 2 July 2014

Bad to the Bone: Are men’s faces evolved for fist fights?

Look in the mirror. What do you see? If you’re a man, you might be looking at the consequences of thousands of years of fist fights. It might not be the most flattering thing to consider but a new theory suggests that the features of men’s faces are more strongly built than those of women so that we are better able to take a punch.

Researchers from the University of Utah have studied the differences in the facial structure of men and women going back millions of years and concluded that the differences we see may be indicative of a violent past. Biologist David Carrier is a firm believer that the ancestors of humans relied on fist fights to sort out who got to mate with who on the African plains.

These ideas fly in the face of conventional wisdom on how the face evolved. People have long assumed that the robust jaws and cheekbones of ancient apes in the genus Australopithecus were the product of tough, plant-based diets. Much like modern gorillas whose diet is made up almost entirely of vegetation that requires a lot of chewing, it was thought that the predecessors of modern humans had strong facial bones to support strong facial muscles needed to grind up leaves and the like. Not so, according to Carrier who after looking at wear patterns on the teeth of Australopithecines concluded that they were likely eating soft fruit, rather than hard nuts.

This presented something of a problem for explaining heavy facial bones. Fortunately Carrier had an idea. As it turns out, in 2012 he co-authored another paper published in the Journal of Experimental Biology explaining how the proportions of the human hand are ideal for making fists. It doesn’t take much of a leap for a fist expert to conclude that apes with thick cheek bones might have used them to better handle frequent punches to the face.

Dr. Carrier’s ideas have been met with a lot of skepticism on the part of other scientists. Just because a fist makes a good weapon doesn’t mean that a fist evolved to be a weapon. It’s a perfect case study in one of the great challenges that scientists face. At the end of the day, you may have used perfectly objective and defensible methods to collect your data; but the tool you use to interpret that data is a human brain... And human brains have biases and preconceived notions. It is one thing to say that men have more robust faces than women, but it’s another to say that you know the reason why.

The key to good science is critical thinking. Look at what is in front of you and question it. That is not to say that Dr. Carrier is wrong, it’s just important to consider alternative explanations. Maybe human faces and hands are designed to help us beat the tar out of each other; but maybe men’s faces are tougher because they got injured more often than women while hunting big game. Maybe our hands evolved to help us manipulate tools and the design just so happened to work as a fist. Or maybe using tools and punching people in the face were equally important in shaping our hands.

In truth, that last explanation is probably a bit closer to the truth. The tricky thing about evolution is that there are so many variables acting on every single trait in an animal’s body or brain at the same time that it should raise flags whenever we read that “The reason for x is y!” Things in the real world are usually in shades of grey, regardless of our ancestors’ black eyes.