Posts Tagged ‘Middle Stone Age’

Coping with climate change drove innovation

June 18, 2013

When and how innovation occurs sometimes seems random and the corporate world has long pursued the creation of “environments” in which innovation can flourish. And while the very definition of what counts as innovation can be debated, it seems to me that it is a changing environment rather than a static environment which is a key ingredient. And it could well be that the greater the change to be handled then the very necessity of coping with that change could be the “mother of all innovation”.

I suspect that some of the most fundamental innovations have been driven by the need not just to survive but also to thrive in “rapidly” changing and threatening environments. And climate change where “rapid” would mean several hundred if not thousands of years would also have been a powerful driver. One advantage in the stone age would have been that humans would have focused on coping with the change as it unfolded and not wasted too much effort in trying to control the climate.

A new paper addresses how climate change could have driven innovation in the stone age centered around the discovery and establishment of new refuges.

Ziegler, M. et al. Development of Middle Stone Age innovation linked to rapid climate changeNature Communications 4, Article number: 1905.

Abstract: The development of modernity in early human populations has been linked to pulsed phases of technological and behavioural innovation within the Middle Stone Age of South Africa. However, the trigger for these intermittent pulses of technological innovation is an enigma. Here we show that, contrary to some previous studies, the occurrence of innovation was tightly linked to abrupt climate change. Major innovational pulses occurred at times when South African climate changed rapidly towards more humid conditions, while northern sub-Saharan Africa experienced widespread droughts, as the Northern Hemisphere entered phases of extreme cooling. These millennial-scale teleconnections resulted from the bipolar seesaw behaviour of the Atlantic Ocean related to changes in the ocean circulation. These conditions led to humid pulses in South Africa and potentially to the creation of favourable environmental conditions. This strongly implies that innovational pulses of early modern human behaviour were climatically influenced and linked to the adoption of refugia.

PhysOrg reviews the paper:

According to a study by the Universitat Autònoma de Barcelona, the University of Cardiff and the Natural History Museum in London, technological innovation during the Stone Age occurred in fits and starts and was climate-driven. Abrupt changes in rainfall in South Africa 40,000 to 80,000 years ago triggered the development of technologies for finding refuge and the behaviour of modern humans. This study was recently published in Nature Communications.

Archaeological and genetic evidence suggests that modern humans (the modern form of Homo sapiens, our species) originated in Africa during the Stone Age, between 30,000 and 280,000 years ago. The latest  in southern Africa have shown that technological innovation, linked to the emergence of culture and modern behaviour, took place abruptly: the beginnings of symbolic expression, the making of tools from stone and bone, jewellery or the first agricultural settlements.

An international team of researchers has linked these pulses of innovation to the climate that prevailed in sub-Saharan Africa in that period.

Over the last million years the  has varied between  (with great masses of ice covering the continents in the northern hemisphere) and interglacial periods, with changes approximately every 100,000 years. But within these long periods there have been abrupt climate changes, sometimes happening in the space of just a few decades, with variations of up to 10ºC in the average temperature in the polar regions caused by changes in the Atlantic . These changes affected rainfall in southern Africa.

The researchers have pieced together how  varied in southern Africa over the last 100,000 years, by analysing  deposits at the edge of the continent, where every millimetre of  corresponds to 25 years of sedimentation. The ratio of iron (dissolved from the rocks by the water during the rains) to potassium (present in arid soils) in each of the millimetre layers is a record of the sediment carried by rivers and therefore of the rainfall throughout the whole period.

The reconstruction of the rainfall over 100,000 years shows a series of spikes that occurred between 40,000 and 80,000 years ago. These spikes show rainfall levels rising sharply over just a few decades, and falling off again soon afterwards, in a matter of centuries. This research has shown that the climate changes coincided with increases in population, activity and production of technology on the part of our ancestors, as seen in the archaeological records. In turn, the end of certain stone tool industries of the period coincides with the onset of a new, drier climate.

The findings confirm one of the principal models of Palaeolithic cultural evolution, which correlates technological innovation with the adoption of new refuges and with a resulting increase in population and social networks. For these researchers, the bursts of demographic expansion caused by climate change in southern Africa were probably key factors in the origin of modern humans’ behaviour in Africa, and in the dispersal of Homo sapiens from his ancestral home.



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