Beringia and Beyond: New Dental Perspectives on the Peopling of the Americas

Variation in the shape of human teeth has historically been an instrumental tool from which to discern the migration patterns of people into the Americas. This was especially true before the advent of today’s DNA technologies that now provide a more precise means through which to assess relatedness between populations.

In this AAAS talk, I will provide an overview of the population history revealed by differences in the shape of teeth – differences that include the two shown in this figure (shoveling of the incisors in the front of the mouth, and the number of cusps on teeth in the back of the mouth). The frequencies of traits like these differ across populations. An assessment of the frequency differences across populations lends support to the Beringia Standstill Model proposed from an analysis of mtDNA.

As biologists and geneticists elucidate the relationship between genes and anatomy, variation in the shape of our teeth can reveal even more about our past. There is new evidence that the shape of the incisors is influenced by genetic variation that also influences variation in hair thickness and sweat glands. Nearly all Native American populations have shovel-shaped incisors. This very high frequency of shovel-shaped incisors may be the result of selection that occurred on hair or sweat glands over the thousands of years that their ancestors lived in the Arctic prior to migration across the Bering Strait.

The combination of population genetic, quantitative genetic, archaeological, skeletal, and developmental datasets promises to yield insights to the selective forces that confronted past human populations, as well as providing insights as to their diaspora.