[muawiyah]

So, how is it that you can check the teeth of someone speaking Old West Gothic and tell that he’s a Viking rather than an Angle?

[worst-case scenario]

The article actually explains all that. Did you read it?

[Psycho_Bunny]

Regional diet can wear teeth differently, and there might be a genetic marker or bite “tell” that's hereditary.

[La Lydia]

Strontium isotope composition of teeth and other skeletal elements can be used to identify the geographic region that an animal or human inhabited, because different regions tend to have distinct Sr isotope compositions, and natural variations in the relative abundance of Sr isotopes are not changed as Sr is processed through the food chain. Therefore, an organism that ingests Sr from one region can have a Sr isotope composition that is different than that of an organism that ingests Sr from another region.