Who made these tools?
Humanity's origin story has gotten increasingly tangled in recent years: New discoveries suggest that Homo sapiens interacted and interbred with other species and ventured out of Africa in more than one wave. Researchers have compared the ancient world to J.R.R. Tolkien's Middle Earth - but instead of hobbits, dwarves and elves, our planet had modern humans in Africa, Neanderthals in Europe, Homo erectusin Asia.
Now, a treasure trove of ancient stone tools suggest that humans' circuitous path to modernity also wound through India.
In a paper published in the journal Nature, researchers described thousands of stone implements uncovered at Attirampakkam, an archaeological site in southern India. The tools span some million years of history, they say, and illustrate the evolution of big, blunt hand axes into finely sculpted stone points. Starting roughly 385,000 years ago - long before modern humans are thought to have arrived in India - it appears that an advanced toolmaking culture was developing there.
How did these techniques reach India so early? "That's the multimillion-dollar question," said archaeologist Shanti Pappu, founder of the Sharma Center for Heritage Education and a co-author of the report.
No remains were found alongside the Indian tools, meaning it's impossible to determine whether the tools were produced by modern humans or one of our hominin cousins. If they were produced by members of our species, it would significantly shift the timeline of human evolution. But that's a big "if," Pappu acknowledged.
At the very least, she said, the discovery suggests "complex interactions" between the mystery hominins in India and their relatives around the globe.
"It shows that simple linear narratives of dispersal only at certain time periods is incorrect," Pappu said.
Modern humans evolved in Africa, and the oldest known bones that could feasibly belong to our species were found in a Moroccan cave and dated to 300,000 years ago.
Upon leaving Africa, Homo sapiens would have encountered an array of distant relatives. Paleoanthropologists believe the first hominins left Africa about 1.7 million years ago, though there's some dispute about what species those early migrants belonged to.
The first hominins to leave Africa - whoever they were - carried with them oval- and pear-shaped hand axes used to pound and scrape food - a technology called Acheulean. The oldest tools found at Attirampakkam, which are more than 1 million years old, were crafted in this tradition.
But in a second batch of implements uncovered from a rock layer that spans 385,000 to 172,000 years ago (plus or minus roughly 50,000 years on either end), those heavy hand axes give way to smaller, more sophisticated points. One of the points even appears to have a groove that would allow it to be affixed to some kind of projectile, like a spear.
This kind of technology has long been associated with Neanderthals and Homo sapiens in Europe, the Middle East and Africa, and it wasn't thought to have arrived in India until humans reached south Asia about 100,000 years ago. Known as Levallois, this technique is associated with significant advances in human cognition, because such tools can't be crafted without the ability to think abstractly and plan ahead.
The team of researchers for the find comprises Shanti Pappu & Kumar Akhilesh (archaeologists: directing the project), Yanni Gunnell (University of Lyon, geomorphologist), A.K.Singhvi, Haresh Rajapara and A.D.Shukla from the Physical Research Laboratory, Ahmedabad, India (responsible for the geochronology). They throw more light on what these finds mean.
What is the significance of Attirampakam? Have there been other digs in this area?
This is part of a long-term project in south east India, that we are directing, with over 20 years of work at this site to investigate prehistoric cultures and past environments in this region. This is only one of several sites we are looking at. The site is significant as our long-term multidisciplinary research has yielded new information in terms of the chronology of successive Acheulian and Middle Palaeolithic (MP) occupation, nature of the stone tool assemblages, implications for behavioural changes and past climatic changes.
How many such tools were uncovered?
The site has yielded many artefacts with Lower Palaeolithic Acheulian cultures at the base of a thick stratified sequence, and overlying MP horizons. Here, we analysed over 7,000 artefacts.
What is the significance of these tools in establishing the presence of hominins or modern humans in that geographical area?
Our message is very simple. Over a period ranging from around 385 64 ka (kilo annum, thousand years), we see processes of transitional from the preceding Acheulian culture leading to the establishment of a new behavioural package seen in the changes in the stone tool assemblage. This process of a complete shift in tool-making preferences continued until around 172 ka at this site. So we are not speaking of one date, but a range of dates, and not of one tool-type but a whole change in technology. Yes, this is prior to one theory that suggests later arrival of this culture with modern humans. We ourselves do not commit to correlating tools with species. Given the evidence at the moment, it is too speculative.
Why is finding out who were these 'people' a "million-dollar question"?
Very few fossils have been found in India, only one partial cranium and some post-cranial remains uncovered in the Narmada region of Central India. It is very difficult to correlate these with our assemblages, and we err on the side of caution in correlating tool-types with species.
Have relatively few paleontologists focused their efforts in India?
Not at all. India has had a long and very productive history of research in Palaeolithic archaeology, with numerous sites discovered right from 1863 onwards. In comparison to the amount of research in Africa, Europe or elsewhere, we have comparatively fewer excavated and dated sites.
Yanni Gunnell: We would say that India suffers from two issues: a poorer preservation potential of fossils because of its surface geology and humid environment (powerful and destructive monsoon rivers, etc.), as mentioned just now; and limited exposure of its scientific community to international media, which has failed to put India on the map of world prehistory.
What is the way forward?
We need more funding for long-term sustained research projects across India to resolve these questions. Our work is only a small part of a huge puzzle. We don't have all the answers as yet.
Yanni Gunnell: Even assuming we find some more remains, we must rely on dating methods that reach much further back in time that radiocarbon dating. Such radiometric methods correspond to cutting-edge research in physics and chemistry, with potential pitfalls in regions such as monsoon India, where the geological conditions for preserving such ancient remains are less favourable that in the arid regions of Afro-Arabia, and in regions where ongoing volcanic activity such as the African Rift Valley. Volcanic rocks and debris can not only preserve material by burying it, but can also be directly dated with methods not applicable in other circumstances - such as India.
Will this discovery make a big shift in a review of what we know so far?
Shanti Pappu & Kumar Akhilesh: We hope it will stimulate debates.
Yanni Gunnell: Rome wasn't made in a day, and we don't shoot from the hip.
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