Teeth taken from graves sites in the ancient city of Harappa in the Indus Valley suggest the people were not born there, but migrated there from the hinterlands.
When tooth enamel forms, it incorporates elements from the local environment from the food one eats, the water one drinks, and the dust one breathes.
When researchers looked at remains from the ancient city of Harappa, located in what is known today as the Punjab Province of Pakistan, early molars told a very different story than later ones, indicating their owners had not been born in the city where the teeth were found.
Rare burial sites
Much of what modern researchers have gleaned about our common ancestors, particularly those from Egypt and Mesopotamia, comes from well-studied tombs and burial sites.
Discovering the narrative of peoples from the Greater Indus Valley—which comprises much of modern-day Pakistan and northwest India—is more challenging because the text of the Indus Valley civilization is still undeciphered, and known and excavated burial sites are rare.
For a new study, published in the journal PLOS ONE, researchers compared the dental enamel and chemical anaylyes of the water, fauna, and rocks of the time by using isotope ratios of lead and strontium. The findings illuminate the lives of the individuals buried in those rare grave sites more than 4,000 years ago.
In its heyday, about 50,000 people lived in Harappa—although the number of individuals represented by skeletal remains across the entire culture area totals in the hundreds.
Were outsiders welcomed?
“The idea of isotope analysis to determine the origin of individual migrants has been around for decades,” says Benjamin Valentine, who was finishing his doctorate in anthropology at University of Florida at the time of the study and is now a postdoctoral student at Dartmouth University.
“But what people haven’t been doing is looking at the different tooth types, essentially, snapshots of residents during different times of individuals’ lives. We didn’t invent the method, but we threw the kitchen sink at it.”
The researchers discovered that the people in the Harappa grave sites weren’t born there.
“Previous work had thought the burial sites represented local, middle-class people,” says coauthor George Kamenov, professor of geological sciences. “There was no notion that outsiders were welcomed and integrated by locals within the city. It’s not clear why certain young hinterland people were sent to the city.”
Biological anthropologist John Krigbaum, Valentine’s dissertation adviser, contributed to the work.
Source: University of Florida