Monday, March 26, 2018

'Out of Africa', in India: A conversation on the Early Middle Paleolithic site of Atirampakkam, Tamil Nadu

A recent article in Nature titled "Early Middle Palaeolithic culture in India around 385–172 ka reframes Out of Africa models" has caused quite the uproar in news media in India and around the world, as it debunks the long-believed theory that complex tool-making emerged in the subcontinent after an influx of modern Homo Sapiens from Africa approximately 130,000 years ago. In fact, tools found at Attirampakkam, a site in Tamil Nadu, have been luminescence dated to 385,000 years old.
South Asian Archaeology spoke to the team, comprising Dr. Shanti Pappu, Dr. Kumar Akhilesh, Professor Yanni Gunnell and Professor A.K. Singhvi via email; and their answers have been consolidated. Drs. Shanti Pappu and Kumar Akhilesh are from the Sharma Centre for Heritage Education, India. The site was dated by Professor A.K. Singhvi and his team from the Physical Research Laboratory, Ahmedabad, and the geomorphology is being studied by Professor Yanni Gunnell, Université de Lyon, Department of Geography, France.

Q: What is the "Out of Africa" theory as it relates to stone tool technology, and how has it shaped our understanding of early Homo Sapien presence in the Indian subcontinent? 
There are several debates on the timing and nature of the dispersal of differing species out of Africa beginning more than a million years ago. As regards India, the earliest possible dispersals of hominins with an Acheulian culture are dated to around 1.07 to 1.7 million years ago, as seen from evidence at the earliest levels in Attirampakkam.
As regards the Middle Palaeolithic culture, one theory suggests that modern humans with a Middle Palaeolithic culture migrated to India around 140,000-90,000 years ago. Other theories dispute this, suggesting that modern humans were in India only later, around 46,000 years ago, and that prior to this, the Middle Palaeolithic tool-kits may be attributed to some other archaic species.
Q: What does the evidence found at Attirampakkam tell us about the people who lived here, and whether these tool technologies were developed independently? 
The site of Attirampakkam has a thick deposit with different layers and artefact assemblages. At the base, we have the Acheulian that is dated from around 1.07 to 1.7 million years ago. These occur deeply stratified at the base of a thick sequence of sediments. The stone tool assemblage comprises typical Acheulian tools like handaxes, cleavers and other large cutting tools, generally made on large flakes (>10 cm), along with other tool components. These are typical of most Acheulian sites in India.
Figure 1: Acheulian tools

Above this, we have around 3 metre thick deposits of sediments. There is a disconformity or a hiatus between the lower Acheulian and the upper transitional and Middle Palaeolithic layers.
At the base of the upper sequence (Layer 5), termed Phase I, we note that at 385 ± 64 thousand years ago (ka), the typical Acheulian technological strategies of producing large tools on flakes (generally>10 cm) and typical stone tool-kit gradually disappears.
There is a dramatic shift towards making small tools using different techniques. This represents a huge behavioural shift. This we term a transitional phase from the Acheulian to the Indian Middle Palaeolithic. We see the first appearance at the site of technologies called Levallois and blade.
In the succeeding overlying layers (Layers 5 to 2) termed Phase II, dating from around 268 ± 68 ka to around 172 ± 41 ka, we note that a typical Indian Middle Palaeolithic assemblage is found, dominated by small flake tools, such as small scrapers on flakes, as also with continued evidence of use of the Levallois and blade technologies, already appearing in Phase I.
This suggests that processes marking transitions from the Indian Acheulian and the appearance of the Middle Palaeolithic were occurring in India far earlier than previously thought.
This does not deny later population dispersals, but suggests a rethink of existing models and an appreciation of the complexity involved in processes of transition and cultural evolution of this particular cultural phase.

This has no implications for the species of the tool-makers as we lack fossils at this site and we cannot correlate tool-types with species for this time period, keeping in mind that several species were making similar tools elsewhere in the world. To disentangle degree of local vs. external influences in the evolution of the Indian Middle Palaeolithic is unclear, as we have stated in the conclusion of our paper.
Q: What made Attirampakkam a good site for the kind of study you've conducted? 
The site was discovered way back in 1863 by the British geologist Robert Bruce Foote (often known as the ‘Father of Indian Prehistory') and William King. It was later investigated by numerous scholars. Our excavations at this site are part of a larger project investigating prehistoric sites in northern Tamil Nadu, directed by Dr. Akhilesh and Dr. Pappu. We focused on this site as it has huge potential to address questions on long-term prehistoric behavioural changes. Over 20 years of research at this site is still yielding new data on the past.
Figure 2: Excavations at Atirampakkam
Q: What is luminescence dating? What are the conditions needed to do this kind of testing of stone tools? 
Luminescence dating measures the time spent in the dark by minerals after they were buried in a sediment deposit. When exposed to the ambient radioactivity of the deposit (small doses of alpha, beta and gamma rays emitted in all directions by naturally radioactive minerals present in the mix), a crystal of quartz or feldspar will accumulate energy in the form of electrons that get trapped within imperfections of the crystal lattice. When the sample is collected and heated in the laboratory, the energy is re-emitted as light and measured following various physical techniques. On a hillslope or in a river, exposure of the crystal to sunlight during transport will soon reset the energy signal to zero as a result of heating and light stimulation. The radiometric clock thus only starts to tick after the burial of the ‘reset' crystal. Given the basic principles of stratigraphy, the burial age of the crystal will be identical to the burial age of any archaeological artefact lying immediately alongside it (i.e. at the same depth) in the stratigraphy. The chronology of the cultural sequence at Attirampakkam was obtained from a series of samples collected at different depths in the stratigraphic column. As expected, they each displayed contrasting burial ages. What was more unexpected was their great antiquity.
Q: What is the significance of this finding?
Our results show that components of an Indian Middle Palaeolithic culture appear far earlier than the presumed dates of around 140 ka, 125 ka or 90 ka years ago when it is believed by some archaeologists that migrations of modern humans out of Africa brought these cultures to India. While we do not deny later dispersals, we show that the simple linear model of dispersals is unlikely and that complex processes were at play, involving transitions from the preceding Acheulian. This work has global implications in terms of a need to reframe current models of dispersals out of Africa and suggests a need to examine complexities in the record.
Q: What are the kinds of fossil finds that have been associated with stone tools, and what is the likelihood of finding fossils or bones at sites like Attirampakkam? 
The likelihood of finding fossils in this environment is very low owing to local soil conditions. There are discoveries of hominin fossils in the Narmada region, Central India (a partial cranium and other post-cranial remains), but at present these are very difficult to correlate with our assemblages, and so we remain cautious on the species.
Q: What do you mean by "placemaking" in the context of the finds at Attirampakkam? Why is this significant in the context of how prehistoric sites have been studied in the subcontinent thus far?
Hominins returned periodically to this site for over a million years for specific reasons. The reasons changed through time, as the environment at the site changed, but the locality was always attractive for specific tasks through time.
Q: What are the next steps in your research? 
We are continuing with our research project in this region, continuing research at Attirampakkam and expanding into new areas of stone tool analysis and planning excavations at other sites in the region.

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