Droughts Altered Ancient Civilization's Lifestyle in the Indus Valley, Study Finds

2023

New research conducted by scientists from the University of Cambridge and other institutions has shed light on the impact of droughts on the ancient Indus Civilization. By analyzing a stalagmite from Dharamjali Cave in the Himalaya, the researchers reconstructed rainfall patterns spanning 4,200 to 3,100 years ago.

The study revealed a 230-year period characterized by increased summer and winter drought frequency between 4,200 and 3,970 years ago. Within this timeframe, multi-decadal aridity events occurred around 4,190, 4,110, and 4,020 years ago. These findings indicate deficits in both summer and winter rainfall during the urban phase of the Indus Civilization, prompting the adaptation of flexible, self-reliant, and drought-resistant agricultural strategies.

Professor Cameron Petrie, an archaeologist from the University of Cambridge, emphasized the significance of these findings, stating, "We discover explicit confirmation that this duration was not a brief emergency but a gradual alteration of the environmental circumstances in which the Indus population resided."

To map out past precipitation patterns, Professor Petrie and his team examined growth strata in the stalagmite obtained from Dharamjali Cave, near Pithoragarh, India. By analyzing various environmental markers such as oxygen, carbon, and calcium isotopes, they were able to reconstruct rainfall during specific seasons. Precise dating techniques were also employed to determine the timing and duration of the arid periods.

Dr. Alena Giesche, another researcher from the University of Cambridge, explained, "Numerous indications enable us to assemble the characteristics of these dry spells from different perspectives — and verify that they align."

The study revealed distinct intervals of reduced precipitation during both summer and winter seasons. This evidence is crucial for understanding the impact of climatic changes on human societies. Professor Petrie added, "The dry spells during this duration extended for longer durations, to the extent that the third one would have lasted for multiple generations."

These findings support existing evidence linking the decline of the Indus cities to climate shifts. However, until now, little was known about the duration and specific seasons in which the droughts occurred. Dr. Giesche noted the importance of this additional information, stating, "That additional information is genuinely vital when we reflect on cultural recollection and how people adjust to environmental changes."

Archaeological evidence indicates that during the two-century period of drought, the early inhabitants of the Indus Civilization adopted several measures to adapt and sustain their way of life. Larger urban areas were abandoned in favor of less populated rural settlements located towards the eastern frontier of the territory. Cultivation practices shifted to rely more on summer crops, particularly drought-resistant millets, reflecting a more self-reliant lifestyle.

Dr. David Hodell, also from the University of Cambridge, highlighted the significance of paleoclimate records in understanding cultural changes, stating, "Megadroughts have recently been widely cited to account for various cultural changes, including those in the Indus Valley." He added, "This situation is now changing because paleoclimate records are becoming increasingly advanced in pinpointing alterations in precipitation on a seasonal and yearly basis, which have a direct impact on people's choices."

The study provides valuable insights into how ancient civilizations adapted to environmental challenges, emphasizing the resilience and resourcefulness of the Indus Civilization in the face of prolonged droughts.