Search This Blog

Wednesday 25 May 2016

Oxygen isotope in archaeological bioapatites from India: Implications to climate change and decline of Bronze Age Harappan civilization

 Anindya Sarkar, Arati Deshpande Mukherjee, M. K. Bera, B. Das, Navin Juyal, P. Morthekai, R. D. Deshpande, V. S. Shinde & L. S. Rao
The antiquity and decline of the Bronze Age Harappan civilization in the Indus-Ghaggar-Hakra river valleys is an enigma in archaeology. Weakening of the monsoon after ~5 ka BP (and droughts throughout the Asia) is a strong contender for the Harappan collapse, although controversy exists about the synchroneity of climate change and collapse of civilization. One reason for this controversy is lack of a continuous record of cultural levels and palaeomonsoon change in close proximity. We report a high resolution oxygen isotope (δ18O) record of animal teeth-bone phosphates from an archaeological trench itself at Bhirrana, NW India, preserving all cultural levels of this civilization. Bhirrana was part of a high concentration of settlements along the dried up mythical Vedic river valley ‘Saraswati’, an extension of Ghaggar river in the Thar desert. Isotope and archaeological data suggest that the pre-Harappans started inhabiting this area along the mighty Ghaggar-Hakra rivers fed by intensified monsoon from 9 to 7 ka BP. The monsoon monotonically declined after 7 ka yet the settlements continued to survive from early to mature Harappan time. Our study suggests that other cause like change in subsistence strategy by shifting crop patterns rather than climate change was responsible for Harappan collapse.
So,   they don't suggest climate as solely responsible for the de-urbanization  , but it had a significant role .

They also suggest:

The study also indicates increasing dependence on summer crops like millet and has been inferred as a direct consequence of lesser rainfall80. Such pattern have also been found elsewhere in Indus valley where the Harappans shifted their crop patterns from the large-grained cereals like wheat and barley during the early part of intensified monsoon to drought-resistant species of small millets and rice in the later part of declining monsoon and thereby changed their subsistence strategy16,81. Because these later crops generally have much lower yield, the organized large storage system of mature Harappan period was abandoned giving rise to smaller more individual household based crop processing and storage system and could act as catalyst for the de-urbanisation of the Harappan civilization rather than an abrupt collapse as suggested by many workers82,83,84,85. Our study suggests possibility of a direct connect between climate, agriculture and subsistence pattern during the Harappan civilization.

See also :
Sindhu Civilization Was Indeed Harmed Badly By Climate
Indus era 8,000 years old, not 5,500; ended because of weaker monsoon
Did climate change kill the Indus civilization?


Giacomo Benedetti said...

Interesting paper, the theory of de-urbanization due to a change in crops is worth of consideration, although it can be one of the aspects, together with reduction of trade and, of course, abrupt change in the Sarasvatī (and Indus) river. I wonder if the date 4.1 ka for the great drought is correct, maybe is a bit later, between 4 and 3.9 ka, when we have the 'collapse' according to archaeological chronology. Or maybe is the archaeological chronology that must be placed earlier. As Dixit's study on the Haryana lake said: "Although dating uncertainty exists in both climate and archaeological records, the drought event 4.1 ka on the northwestern Indian plains is within the radiocarbon age range for the beginning of Indus de-urbanization"

I remember a presentation at the EASAA conference where a Spanish archaeologist discussed about a drought concentrated in some years at that time, considering that such an event could severely affect the civilization.
It reminds what was described in the Mahabharata about the great drought of 12 years which caused the emptying of towns. Apparently there was something sudden that caused mass migrations and abandonment of sites.

Unknown said...

I find the role of climate to be lesser and lesser with new research. More probable scenario is that IVC originated, and died, with trade across the Arabian sea.

PS: Died in the urban sense. The knowledge of course lives on.

Nirjhar007 said...


Absolutely . I think there was a certain ''intensified period'' of lack of rainfall , which was majorly responsible for the de-urbanization process. Perhaps Mahabharata remembers that drastic time.

Unknown ,

Climate surely had a role, it was the villain behind the changes and certain drastic periods, boosted those changes. Yes , the knowledge surely lives on, you can also check out, this recent article by Giacomo , which focuses on the continuity of Harappan Culture in Sindh-


Unknown said...

Maybe my interpretation is naive, but I feel that the Harappans had a very good handle on monsoon. Yes natural calamities can potentially destroy civilizations, but hard to believe IVC could be wiped out due to droughts. Volcanos yes, but I don't think there is any evidence for that.

Another reason I don't subscribe to the climate theory is that the urban centers are predominantly factory towns. Unlike Mesopotamia and Egypt where cities were for elites (with city gods, etc), IVC cities seem to be constructed primarily for manufacturing products. Mesopotamian trade dies, IVC follows.

I've read Giacomo's article. Thank you, I learn a lot from both of you.