Love ‘em or hate ‘em, our pearly whites reveal multiple clues about human development, evolution, and behavior. Here’s a sneak peak of some of the toothy tales I elaborate on in my new book, The Tales Teeth Tell.
1. Teeth have tiny time lines like tree rings ~ but better! Microscopic secretions made by special cells clock each day of crown and root growth. This marvelous circadian system begins before we are born, continues until our teeth stop growing around age 20, and can be studied in fossils that are millions of years old!
2. Teeth are a boon for forensic scientists, particularly for dental detectives who investigate skeletal remains. This is especially true for learning about juveniles, as their teeth follow a predictable schedule of growth deep inside the jaw. Biological anthropologists like me examine their minute microscopic clocks to determine precisely how long ancient children took to grow up.
3. Wisdom tooth impaction, crooked teeth, and cavities ~ oh my! Dental disease has increased with our soft, sugary, modern diets, and is exacerbated by longer term trends of jaws becoming smaller during the evolution of our species. We can counter these concerns by encouraging kids to avoid sugary foods and exercise their growing jaws with hard or fibrous foods.
4. You only get two sets of teeth during your lifetime — an evolutionary pattern humans share with other mammals, including our favorite furry pets like cats and dogs. Other vertebrates, including sharks and lizards, shed and replace teeth continuously. Birds have gone in a different direction, losing their teeth entirely to rely on their beaks.
5. Since tooth crowns are made up of more than 95% mineral when they finish forming, these durable “rocks” are the most common body part to be recovered in the fossil record of primates. This includes hominins such as the australopithecines that ultimately gave rise to humans over millions of years of evolutionary twists and turns.
6. Modern humans are quite unusual: our species downshifted its growth, forming teeth more slowly over a longer childhood than our ancestors and evolutionary cousins, including Neanderthals. This may have given us more more time to grow our brains or learn complex behaviors before having our own kids. Teeth can also help us to understand the end of the lifecycle. Some scholars have concluded that "old age" only became common very late in our evolutionary history, as there are more fossil human adults with heavily worn teeth than Neanderthal or australopithecine adults.
7. Dental clues debunk “the” Paleodiet. Prehistoric humans and their ancestors ate many foods which varied across the different groups and even within species who lived in diverse environments. We know this because tooth chemistry varies ~ as do microfossils trapped in plaque on teeth that hardens into tartar. Tiny pits and scratches on teeth formed during chewing hard or abrasive foodstuffs also differ within and among human ancestors. Just like nowadays, there was no “one right diet” for all our Paleo predecessors!
8. Teeth are great sources of ancient DNA. The rapidly expanding record of genetic information from both living people and fossil hominins has shown multiple interbreeding events over the past 100,000 or more years. This has answered a long-standing question in paleoanthropology, demonstrating that not only did Neanderthals and modern humans come into contact, they produced offspring whose imprint lives on in modern Europeans, Asians and Australasians. Apparently, I myself carry more Neanderthal DNA than 97% of my European kin!
9. Paleodentistry was a thing ~ but without the padded chair and laughing gas. Teeth from prehistoric humans were drilled into 14,000 years ago — likely to excavate painful cavities that became much more common once high carbohydrate foods began to be cultivated, processed, and ultimately refined industrially. Other primates occasionally get cavities too ~ including fruit-loving chimpanzees — another similarity we share with our closest living relatives.
10. Teeth can be a handy canvas for dental art. Ancient humans began filing, notching, and embedding jewels and metals in their front teeth several thousand years ago. This even included knocking them out for an arresting look or a means of getting a mate!
A bonus tale not in the book: teeth record climate variation that can be read on a weekly scale. We can now learn when prehistoric individuals were born, in which season illnesses were most common, and when mothers stopped nursing their children. And all of this can be learned from a single tooth – more details here.
Tanya M. Smith is an Associate Professor in the Australian Research Centre for Human Evolution at Griffith University. Follow her at @DrTanyaMSmith