It’s very hard to find evidence of how ancient people lived, so we have a very incomplete picture of their lives. But now ancient teeth may be giving us an important hint about the way people lived long ago: they may have been right-handed.
How did these ancient teeth tell about our handedness? That’s a long story.
Teeth Are Tough
The easiest way to establish handedness in a fossil would be using the hands and arms. When you use one limb much more than the other, it develops disproportionately, and they can see that in the fossil.
But the problem is that arm fossils are hard to find. If you’ve ever looked at skeletons representing our primitive ancestors, you see that it’s pretty unusual to get even one complete arm, and getting two is virtually unheard of. So in the past we’ve had to put this question aside.
But teeth, on the other hand, are very durable, and they are among the most common fossils for anything, including our early ancestors. What was needed was some way that we could read handedness in these teeth. And that’s what researchers at Ohio State University did with an ancient jaw from Homo habilis.
Teeth Were Tools
Homo habilis were primitive tool users. They made and used many different tools, but they were short on resources. Being a nomadic people with no domesticated animals, they had to carry everything on their backs, so they leaned heavily on their integrated tool set: hands and, of course, teeth.
H. habilis used their teeth for many things, but mostly as a third hand, similar to the way we might use a vise on a workbench to hold something we were working on. While holding something with their teeth and working on it with tools, they inevitably knocked up against their teeth with the stone tools, and these stone tools left marks on the teeth. By reading these marks, researchers were able to determine that one particular individual was predominantly using his right hand to do the work, because 47% of the marks would have been made with a right-handed motion, compared to only 11% with a left-handed motion (the rest were indeterminate).
How Handedness Affects Your Teeth
Hopefully, you’re not using your teeth as tools. H. habilis could get away with it for many reasons. First, they had a very different set of teeth and jaws than we have. Second, although H. habilis could live into their 50s, their practical life expectancy was more like mid-30s. In other words, they didn’t need their teeth to last as long as ours, so they could take a little more abuse. But if you abuse your teeth and they do get damaged, we can help repair chips, cracks, and other damage.
But even without using your teeth as tools, your handedness can make a bit impact on your teeth, mostly through oral hygiene. When you brush your teeth, you’ll notice that it’s easier to clean one side of your mouth than the other. And it’s likely that side gets noticeably cleaner, too. It will have less tartar, less gum disease, and fewer cavities. We’ll point this out to you so you can do a better job. An electric toothbrush can help with this, but you still need to make sure you’re getting all your tooth surfaces.