Thanks to Science Daily, I’ll never think of my beard the same way again. They’ve got new insight into the evolution of humankind’s most uniquely human feature – trying to pin down why we’re the only animals to have developed chins:
“In some way, it seems trivial, but a reason why chins are so interesting is we’re the only ones who have them,” says Nathan Holton, who studies craniofacial features and mechanics at the University of Iowa. “It’s unique to us.”
New research led by Holton and colleagues at the UI posits that our chins don’t come from mechanical forces such as chewing, but instead results from an evolutionary adaptation involving face size and shape — possibly linked to changes in hormone levels as we became more societally domesticated.
The finding, if true, may help settle a debate that’s gone on intermittently for more than a century why modern humans have chins and how they came to be.
More intriguing, UI anthropologists led by Robert Franciscus think the human chin is a secondary consequence of our lifestyle change, starting about 80,000 years ago and picking up great steam with modern humans’ migration from Africa about 20,000 years later. What happened was this: Modern humans evolved from hunter-gatherer groups that were rather isolated from each other to increasingly cooperative groups that formed social networks across the landscape. These more connected groups appear to have enhanced the degree to which they expressed themselves in art and other symbolic mediums.
The change in attitude was tied to reduced hormone levels, namely testosterone, resulting in noticeable changes to the male craniofacial region: One big shift was the face became smaller — retrenching in effect — a physiological departure that created a natural opportunity for the human chin to emerge.
“What we’re arguing is that modern humans had an advantage at some point to have a well-connected social network, they can exchange information, and mates, more readily, there’s innovation,” says Franciscus
They don’t help us chew; they just make us look more thoughtful while we’re doing it.