You’ve probably heard the term “isotope analysis.” In theory, its a simple idea: people are what they eat and drink. Ratios of carbon and nitrogen in our bones and our teeth allows scientists to tell the relative amounts of animal protein that we eat and drink. It can also be used to distinguish between broad groups of plants, because different paths use different photosynthetic pathways and that determines the amounts of carbon and nitrogen we get from eating different groups of plants. Using carbon and nitrogen ratios, modern scientists can – to a degree – reconstruct the diets of people who died long ago.
There is also differences in strontium isotope ratios, depending on the age of the underlying geology of an area. Are you living on 200 million year old bedrock, or 2000 million year old bedrock? Apparently, it makes a difference. By drinking local water and eating local food, people incorporate the locak strontium isotope ratios into their tooth enamel while their teeth form during childhood. When a skeleton is found, the teeth’s strontium isotope ratio can be compared to the local burial area’s ratio. If its not the same, then the person was not raised there. Of course this only tells us whether they are local or not. It does not help identify where the person migrated from.
