Tropical rainforest archaeology

Just a short not to highlight the publication of a special issue of Quaternary International (volume 249) on human occupation of tropical rainforests, on the theme of how rainforests are themselves artefacts, or "cultural landscapes", to quote from the editorial by Barton, Denham, Neumann and Arroyo-Kalin the papers show "several commonalities can be elicited that enabled hunter-foragers to permanently inhabit rainforest landscapes in different parts of the world"-- which bears on the adaptiveness of Early Modern Human, which lead to cultural parallelisms. In many cases Tropical forests adaptation lead on to agriculture of the more mobile/shifting sort. The volume includes several papers on the Neotropics, Africa and Island Southeast Asia and New Guinea, as well as one on India and Sri Lanka (Kingwell-Banham and Fuller). I have a lot of pages to read and digest, but I previously highlighted on of the African papers by Hohn and Neumann as an excellent example of integrating multiple archaeobotanical datasets, and I regard it as one of the highlights of African Archaeobotany of the past year. I have also previously noted Huw Barton's comparison of rice and sago on Borneo. No doubt many of the other papers in this issue, which I have yet to read, will also be gems.

Parallel origins: true modern human lithics in India (as true for agriculture)

The latest publication from the Petraglia & Korisettar palaeolithic research team, working in South India, was published last week in PNAS—Population increase and environmental deterioration correspond with microlithic innovations in South Asia ca. 35,000 years ago. This study dovetails nicely with recent simulation modelling effort of some UCL colleagues (Adam Powell, Mark Thomas, and Stephen Shennan, director of the Institute of Archaeology), published in Science last month. (The appearance of these two papers close together is entirely coincidental). This simulations suggest that behavioural innovations, such as modern human behaviour, should be expected to emerge when circumstances are right (especially due to demographic factors of higher interactoing populations), and to be maintained only if demographic circumstances permit (and therefore disappear if populations decline).

These two studies together represent importance counters of an orthodoxy that sees ‘modern’ behaviour as emerging once, and therefore being a great invention when hard cognitive architecture came into place, perhaps even driven by a key genetic mutation for intelligence. Such is the orthodoxy implied by classic textbooks on human evolution, such as by Richard Klein (at least as was used when I was a student) or the recent reviews by Paul Mellars (e.g. his Science paper of 2006). In this view modern humans, heir cognitive abilities and the behavioural application of those abilities emerged once (in Africa) and spread out of Africa (once) to bring intelligent modern everywhere else (perhaps at sometime between 60,000 and 40,000—depending on whether one prefers to emphasize the earliest possible dates for Australia or the Upper Palaeolithic transition in Europe). The evidence from South Asia shows clearly that toolkits were middle Palaeolithic (and in this sense not ‘modern’) from >75,000 to 35,000 years ago, and yet genetics suggests that these would have been anatomically modern humans (and they must have moved through South Asia earlier than their arrival in Australia sometime between 60,000 and 50,000). The bottom line is there is a good evidential case to be made, congruent with the modelling of Powell et al., that the cognitive architecture for modern behaviour was around but the innovations that we regard as ‘modern’ emerged when social and environmental circumstances demanded.

There is a parallel here to where thinking on agricultural origins is moving. There has long been an orthodoxy that agriculture was a great and rare invention, and that agriculture came to most regions by the migration of farmers from a few centres of the influence of a good idea. In the more extreme cases, only 3 centres of origin (Mexico, Near East and China) are accepted. But the evidence of archaeobotany—where it is available—combined with the biography of wild progenitors, and where avail able the genetics of crops/livestock, suggest that there was many more centres in which societies converged on agriculture—the behavioural changes towards manipulation of the environment in favour of the reproduction of a few food species (domestication, the genetic sense, was an unintended consequence of these behavioural shifts, when the genetics of the species allowed). In my most recent attempt to sift through the combined data, I concluded that there is strong case for 24 separate instances of agricultural origins globally—although as many of these are poorly documented and geographically close together one might reduce this to 13, as per the map below from Purugganan & Fuller:

The point is that agriculture, like modern human behaviour, was not a one time great invention, but the product of social and environmental circumstances to which human groups with the same cognitive potential responded in parallel ways. The question in both cases is: what were the common denominators of those circumstances?