Climate Change, Violence and Disease Contributed to Indus Civilization Demise
Climate change, violence and disease all contributed to the fall of the Indus civilization, whose cities grew quickly from 2200 to 1900 BC, at which point they were generally abandoned.
"The collapse of the Indus [civilization] and the reorganization of its human population has been controversial for a long time," said Gwen Robbins Schug, an associate professor of anthropology at Appalachian State University and lead author of the paper published in the journal PLOS One.
The study, which focuses on human skeletal remains discovered in the ancient city known as Harappa, located in modern-day Pakistan, indicate the Indus people were not the peaceful, egalitarian group so often proposed. Climate and socio-economic strains appear to have affected the socially disadvantaged and marginalized the most, as apparent in the discovery of higher rates of violence and disease in those individuals who were excluded from the city's formal cemeteries. In a site southeast of the city, a small pit containing the remains of men, women and children revealed a 50 percent violence rate for the 10 preserved crania. Meanwhile, more than 20 percent showed signs of having had leprosy.
Around this time, a weakened monsoon system was triggering hydro-climatic stress that would have impacted areas like Harappa, recent reconstructions of the Beas River Valley show.
"Scientists cannot make assumptions that climate changes will always equate to violence and disease," Robbins Schug said. "However, in this case, it appears that the rapid urbanization process in Indus cities, and the increasingly large amount of culture contact, brought new challenges to the human population."
The lesson is one that still applies today, according to the study's authors.
"Human populations in semi-arid regions of the world, including South Asia, currently face disproportionate impacts from global climate change," the researchers wrote. "The evidence from Harappa offers insights into how social and biological challenges impacted past societies facing rapid population growth, climate change and environmental degradation. Unfortunately, in this case, increasing levels of violence and disease accompanied massive levels of migration and resource stress and disproportionate impacts were felt by the most vulnerable members of society."