File Photo: Indus Valley Civilization
Ancient people in the Indus Valley apparently did not stay put, as was previously thought, a team of US and Indian researchers has found by examining 4,000-year-old teeth.
When tooth enamel forms, it incorporates elements from the local environment - the food one eats, the water one drinks, the dust one breathes, researchers said.
When the researchers looked at remains from the ancient city of Harrappa, located in what is known today as the Punjab Province of Pakistan, individuals' early molars told a very different story than their later ones, meaning they had not been born in the city where they were found.
The text of the Indus Valley Civilisation remains undeciphered, and known and excavated burial sites are rare.
The new study illuminates the lives of individuals buried more than 4,000 years ago in those rare grave sites by providing a novel comparison of the dental enamel and chemical analyses of the water, fauna and rocks of the time, using isotope ratios of lead and strontium.
In its heyday, Harrappa held a population of 50,000, although the number of individuals represented by skeletal remains across the entire culture area totals in the hundreds.
"The idea of isotope analysis to determine the origin of individual migrants has been around for decades. But what people haven't been doing is looking at the different tooth types, essentially, snapshots of residents during different times of individuals' lives," said Benjamin Valentine from the University of Florida.
The researchers, including Vasant Shinde and Veena Mushrif-Tripathy, from the Department of Archaeology, Deccan College Post-Graduate and Research Institute, Pune discovered that the people in the Harrappa grave sites were not born there, but migrated there from the hinterlands.
"Previous work had thought the burial sites represented local, middle-class people. 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.
"All told, these novel methods provide windows into the life history of past people and underscore the role of interdisciplinary approaches to illuminate dynamics of human migration," Dr Valentine added.
The study was published in the journal PLOS ONE.