Coastal Dispersal of Modern Humans into Asia 55,000 Years Ago?

Sir Paul Mellars and colleagues have recently published an article in the Proceedings of the National Academy of Sciences, “Genetic and Archaeological Perspectives on the Initial Modern Human Colonization of Southern Asia“.  The authors claim that modern humans utilized coasts to disperse out of Africa about 55,000 years ago. According to the authors, the movement is marked by small blade technologies, analogous to stone tools made in the Howiesons Poort industries of southern Africa. They claim such tools originally arose in southern Africa and diffused to East Africa.  From there, groups of modern humans left Africa and carried microblade toolkits, together with symbolic items (beads, incised and decorated items) and advanced forms of material culture (such as bone tools) across southern Asia.  These modern humans, according to this theory, then replaced archaic humans in places like India, who were still using less-advanced Middle Palaeolithic core and flake technologies. This ‘Howiesons Poort-like’ dispersal contrasts sharply with a series of publications which have advocated that modern humans may have left Africa at an earlier date, consistent with fossils of Homo sapiens in the Levant between 130-70,000 years ago.  

There are a series of problems with the ‘Howiesons Poort’ dispersal, which we have commented on in the media. One of the biggest problems is that there are no microblade toolkits in India at 55,000 years ago (the ones from South Asia pictured to the left date to between 30-40,000 years ago). Another significant problem is that there is zero evidence for a coastal dispersal along the Indian Ocean rim. For further critiques on both the archaeology and genetic findings presented by Mellars and colleagues, see two thoughtful blog posts, “Dienekes’ Anthropology Blog” and “For What They Were…“.

Slow and Repeated Terrestrial Movements of Humans across Southern Asia

Southern Asia during a wet period (see Boivin et al., 2013).

Southern Asia during a wet period (see Boivin et al., 2013).

In a major counter-argument against the consensus view of “Out of Africa”, a new article by our team contends that human movements across Southern Asia would have been slow, continental advances during humid periods, and contractions (and even extinctions) during arid periods.  This is opposed to the view that modern humans moved rapidly out of Africa and across Asia circa 60,000 years ago using coastal corridors.  Mapping of environments from Arabia to Southeast Asia indicate dramatic variability in habitats. We argue that differences in environments would have shaped demographic responses through time.  For instance, we contend that populations in Arabia would have met with major challenges during dry periods, but those in India would have been less effected, while recognising that ecological settings were constantly being reshaped across the subcontinent. Movements further eastwards would have been facilitated by break up of forest cover during dry periods, thus leading to dispersals to Australasia.  Major revisions in genetic coalescence ages, based on nuclear genome studies, suggest that Out of Africa movements may date to 120,000 years ago, which would correspond with fossils of Homo sapiens in the Levant and Middle Palaeolithic technologies in southern Asia.  

For further information, click here:  “Human dispersal across diverse environments of Asia during the Upper Pleistocene“.

Most Accurate Age for the Toba Volcanic Super-eruption

Toba preceded global cooling, indicating that the eruption did not cause a climatic downturn (after Mark et al., 2013: Figure 9).

Toba preceded global cooling, indicating that the eruption did not cause a climatic downturn (after Mark et al., 2013: Figure 9).

The latest study of the age of the Toba eruption places it to 75.0 ± 0.9 ka.  The new, highly precise, argon-argon dating method, is highly significant in that it demonstrates that the Toba Super-eruption did not cause global cooling (stadial 20). Moreover, air-fall ash from two valleys in India convincingly demonstrate that the ash associates with Middle Palaeolithic industries, and not older ones, as has been argued by some researchers. Of great importance to archaeologists, the ash at can be used as a signature horizon, facilitating stratigraphic and temporal correlation throughout India. The robust, high precision age can also be used to link disparate palaeoclimate records across the globe.  For further information, click here:  “A high-precision 40Ar/39Ar age for the Young Toba Tuff and dating of ultra-distal tephra: forcing of Quaternary climate and implications for hominin occupation of India“.

Middle Palaeolithic Occupations along Lakes in Northern Arabia

A major new archaeological survey and excavation programme in northern Arabia led to the recent discovery of several stratified Middle Palaeolithic sites.  The recovery of buried and well-preserved artefact industries is a first-of-its-kind discovery in Saudia Arabia, where most Palaeolithic sites are only known from the surface. Palaeoenvironmental research demonstrated that the sites were situated along the edges of lakes during humid periods. Analysis of plant Slide1remains established that the occupations would have been in a grassland environment supporting some trees probably growing along the lake margins. As demonstrated by satellite imagery, human (and animal) movement into the region was possible owing to the vast network of rivers, which would have acted as corridors for hunting and gathering populations. One major question remains: what happened to these Middle Palaeolithic populations once the environments became increasingly arid?

Read more about this research in the open-access journal, PLoS ONE. To see the article, click here: “Hominin Dispersal into the Nefud Desert and Middle Palaeolithic Settlement along the Jubbah Palaeolake, Northern Arabia“.

Rock Art in India Dated to the Mesolithic

Engraving at Billasurgam

Engraving at Billasurgam

A recent article by our team in the Journal of Archaeological Science reports on an engraving in the Billasurgam Caves of southern India.  The rock art was radiocarbon dated to 5000 years before the present, suggesting that hunter-gatherer communities produced the engraving.  This is the oldest dated rock art in the Indian subcontinent. For further information, see the article:  “Mid-Holocene age obtained for nested diamond pattern petroglyph in the Billasurgam Cave complex, Kurnool District, southern India“.

Climate Shifts at Olduvai and Cognitive Change

At Olduvai Gorge, researchers have found that the landscape fluctuated rapidly.  Rapid climate changes may be linked with key events in human evolution, including cognitive changes.  The researchers suggest that mental developments within the human lineage may have been linked with a highly variable environment.  Two articles have recently been published in the journal PNAS.  See: “Ecosystem variability and early human habitats in eastern Africa“, and “Water, plants, and early human habitats in eastern Africa“.