Friday, 27 February 2015

Mesolithic cereal trade in Europe?

This week's Science includes in ancient sedimentary DNA study by Oliver Smith, Robin Allaby and colleagues from sediments from an archaeological site sealed beneath the English Channel, with evidence that wheat was decomposing on this Mesolithic site 8000 years ago. Such a claim is obvioulsy a big deal for archaeologists, it is counter to our accepted narrative of the introduction of cereals with Neolithic farming immigrants around 6000 years ago. No surprisingly it has received science media attention, both in Science and in New Scientist, as well as a learned commentary from Gregor Larson; and despite a busy teaching week I have been asked for comments. Here I give my full extended comment. While I agree that we really need more evidence to clinch this from additional sites, and I would prefer directly radiocarbon dated grains, I also don't think this requires a complete overhaul of what we know about the introduction of sustained farming around 4000 BC.

This paper is methodologically impressive. They have developed a robust phylogenetic approach to cautiously ID sedimentary aDNA. The deposits seem well dated and sealed by rising sea-levels. So we are left with the challenge of fitting this to our world view as archaeologists. 

This report is sure to be heavily debated, and I guess many archaeologists will reject this out of hand. But that is perhaps like the ostrich with its head in the sand. I would certainly be happier with an AMS-dated cereal grain, but this new evidence tells us we need to be actively looking for those Pre-Neolithic traded grains.

I suppose this will reopen the debate about claims for Mesolithic cereal pollen grains, which have been claimed from sites here and there in Britain and France. Most archaeologists have rightly tended to follow the critical assessment of these, represented for example by the writings of Prof Behre, a senior archaeobotanist and doyen of anthropogenic pollen indicators (e.g. Behre 2007). I expect new scrutiny of such finds, as they could also relate to a pioneer phase of small scale cereal adoption.

From Larson 2015
This find does not mean the Neolithic needs to redated. The Neolithic in Britian is well dated to about 4000 BC which sees a rapid rise in human population together with evidence for emmer wheat, barley and livestock. This follows a spread of agricultural populations, uniformly with big demographic booms across central and western Europe (e.g work by Shennan et al. in Nature Comms, 2013). This I think is still clear. But the New wheat DNA from the English channel requires us to think in terms of small scale pioneers operating beyond the frontier of farming spread and trading with Foragers, and beyond that foragers trading with each other. Mesolithic foragers were well adapted to their environments given their population density so this would not have been about trading food as needed calories but about foodstuffs that were rare, exotic and valuable. I would guess these early cereals would have been symbolically charged as exotica much like spices in much later times. In regions with obsidian we know Mesolithic populations had long distance trade networks. This new evidence suggests long distance networks also moved perishables, including edibles.

I think we can see this as on par with the food "globalization" episodes in much later prehistory, such as the Bronze Age. When sorghum and other African crops arrived in India 4000 years ago, or wheat arrived in China in the third millennium BC, these edibles proceeded any other material evidence for trade. This implies long distance small scale exchanges in exotica, including what seem to us today as mundane edibles, were highly valued, presumably in part because of the symbolic associations with distance and the exotic. I have written about this in a few places, e.g Fuller et al 2011 in Antiquity or Boivin et al 2012 in World Archaeology (blogged here).

So perhaps what we are seeing is evidence for an early Holocene equivalent-- the Neolithic grain as the tastey exotica in a the Mesolithic world

Younger Dyras cataclism: human or extraterrestrial?

I recently collaborated on a paper that analyzed small scoriaecous (glassy) droplets from flotation samples, focused on site in Syria relating to early agriculture, including Abu Hureyra, Jerf el Ahmar, D’Jades, Tell Qaramel: Thy et al. published Journal of Archaeological Science. Previous some of these from Abu Hureyra samples (which are stored at the UCL Institute of Archaeology), have been included in a study from 18 sites around the world that argued that these Younger Dryas spherules derive from a asteroid impact 12,800 years ago that set off the younger Dryas (see Wittke et al PNAS). The analyses in our recent paper argue that the composition of these can be explained by natural soils on earth being heated to high temperatures, but no unreasonable for human settings, such as house fire. Our study includes sites that are significantly after the alleged asteroid impact, and we note that even later example occur.  Both myself and co-author Willcox are primarily archaeobotanists, which mean we float archaeological sediments in water to recover ancient charcoal and seeds and scoria droplets are light enough and contain air bubbles and so they float along with the charcoal. We find them in many archaeobotanical samples around the world and of many periods, but certainly not in all samples. This suggests that they are formed occasionally by circumstances on ancient human sites.

This article generated considerable science media attention, and some vociferous debate from the proponents of a Younger Dryas impact (which I have previously written critically about on this blog: the vexed issue of "nano-diamonds"). In the US it made it into CBS news and in the UK into the Daily Mail, and, treatments can be followed from the UCL news item.

 Superficially there is much in common between these spherules and the composition of the South India Neolithic ashmounds, where we have large deposits, even mounds, of scoriaceous material, dating from 3000-1400 BC, which appear to be created through intentional burning of built up dung and other deposits in cattle penning sites, reaching temperature of 1200 Centigrade or more leading to scoriaeceous formations.

In the early  Near East we are dealing with similar kinds of temperatures. What is intriguing is that these do seem to be frequent inclusions in samples from early village sites, which suggests that circumstances on these first village lent themselves to large fires periodically. I think they are likely to come from uncontrolled fires, as we expect these to reach really high temperatures in some places. Controlled fires in hearths and ovens and I guess will often be kept at lower temperature more manageable for cooking.  Although I would accept that more experimental work could explore this question. I would see this as a by-product of people building structures and accumulating rubbish fairly densely in these early settlements and not really having fire prevention or fighting practices. Village life also evolved gradually, and it may but that these earlier forms of village were not very well adapted with respect to reducing accidental fires.

Because the Younger Dryas and the asteroid impact have been related to terminal Pleisticene megafaunal extinctions, much of the media attention revolved around this issue. The Daily Mail reporter asked me “Do you think this lends support for the other theories of what may have led to the extinctions of the Pleistocene megafauna? What theory do you favour yourselves?”

I think the obvious big player in megafaunal extinctions is humans, human population growth, the modification of environments and the changing of foodwebs. Human over-hunting is a somewhat simplistic version of this hypothesis. In the Old World the ecosystem space of large herbivores has been mostly replaced by domesticated cattle, sheep, goats, horses and agricultural fields tend to exclude large herbivores. Therefore the habitat available for large herbivores has been reduced by these replacements, while growing human numbers have added to hunting pressure. These are all key developments of the Anthropocene or the “Used Planet” I written about before. This kind of process can be illustrated with the near extinction of American Bison. Yes these were hunted, but the big reason they were greatly reduced is the prairies of the US became land for farming and cattle ranching so much less and much more marginal habitat was left for the bison, so there was no way for them to recover from impacts of hunting. In the Americas domesticated herbivores are less significant but the addition of humans only about 15000 years ago must have massively altered ecologies and food-webs in ways that destabilized large faunal numbers. Climate change added top these pressures, but I do not see a need for extraterrestrial forces in this equation.

Returning to the spherules: Ultimately scientific evidence should be able to determine the source of these nodules and the reality of a Younger Dryas asteroid impact. The final verdict is perhaps not yet in from the wider jury of the research community. In favour of such an impact is, perhaps, the fact the YD look anomalous compared to the onset of previous interglacials (see, e.g. those in Ruddiman’s alignments in his Anthropocene review). However, a crater is missing and a clear smoking gun for this cataclysm is illusory and debatable. Our article is just one such criticism, but see also the astrophysics critique of Boslough et al (2012).

Nevertheless, I think there is a more significant philosophical difference. A cataclysmic younger dryas provides an extraterritorial trigger for megafaunal extinctions and the start of Near Eastern farming. Human actions, modifying environments and improving the techniques and technologies to do so are what drove the major changes of the early Holocene. Some of this may have been response to changing climate, to shifting in photosynthetic productivity brought about by post-glacial rise in carbon dioxide, but those changes were not sufficient on the their own: it was cultural action, niche construction (see, e.g. Bruce Smith 2011) that was the necessary catalyst.  But as the evidence clearly indicates the origins of farming and plant domestication was protracted in the Fertile Crescent and elsewhere, taking millennia of plant evolution, trial and error of human techniques and a messy process of coevolution between culture and it environments (the entangled process of domestication: see this PNAS paper from 2014). There is no strong case for a Younger Dryas trigger to the start of cultivation, and certainly not for the bigger economic transition to domestication and farming. Outside the Near East almost all instances of the transition to domestication and farmer economies occur much later, the later Early Holocene or Mid-Holocene (see. e.g. the summary in Larson et al.from last year in PNAS). We have our own species to blame; I don’t think we need to look to outer space.

Sunday, 5 January 2014

In Memoriam, Professor David R. Harris (1930-2013)

It is with a heavy heart that I report the passing of David Harris during the holiday period, Professor Emeritus of Human Environment at the Institute of Archaeology (UCL) and former director of the institute (1989-1996). Our sympathies go to his widow Helen, their children and grandchildren. He also leaves a hole in the intellectual community of the Institute and wider research community on domestication and agricultural origins. For a few generations of archaeologists he was an influential teacher on past subsistence, drawing on a global and encyclopaedic knowledge of ethnographic subsistence systems and world archaeology. Through his writings, edited volumes, and conference organization, and no doubt peer-reviewing, he influenced generations of environmental archaeologists, especially archaeobotanists, and he promoted a comparative and world approach to the transition from forager to farmer. While I was not a student of his in the classroom, I was heavily inspired by his writing on tropical and savannah cropping systems [e.g. 1967, 1972, 2006, 1980 book], on the spectrum transitional subsistence systems that included pre-domestication cultivation (while he did not coin this term, he probably did more than anyone else, to promote its use and to clarify the concept, in part through a series of highly influential and reproduced diagrams-- e.g. Harris 2007, or this 2007 derivative). He was also a dedicated and knowledgible historian of the Institute of Archaeology (e.g. 1997), of Gordon Childe's work, and their influences on the development of Neolithic research.
David Harris studying swidden farming in the upper
Orinoco River, Venezuela, 1968 (from AI 9)

When I joined the institute, David become a mentor, friend and frequent discussant; he informed my ideas, the direction of my research, and always made me look wider, inter-regionally. In many ways he was a unique figure because he adopted archaeology, having moved to the Institute as Professor of Human Environment in 1980 after some two decades teaching in Geography (in UCL Geography from 1964). He had long had predilections for archaeology, indicated by his involvement in the Ucko and Dimbleby conferences on "The domestication and exploitation of Plants and Animals" and "Man, Settlement and Urbanism". His papers on tropical agriculture and the importance of vegeculture were highly influential in encouraging the development of tropical archaeobotanies, from the Neotropics to Africa to New Guinea. His recruitment of Gordon Hillman led an fruitful and extremely influential partnership, both for research, synthesis (their jointly edited book, Foraging and Farming, remains in many ways unparalleled). His contributions were in many world regions, from early work in the Caribbean and Neotropics (e.g. 19621971), the American Southwest (e.g. 1966), to the Torres Straits islands (e.g. 1995), the Fertile Crescent and his more recent work on Djeitun in Central Asia (e.g. 1997;  2010 book). He is well-known for his clear working definitions of slippery concepts, and his monumental syntheses, often streamlining what was the best current knowledge of the origins of agriculture in various regions, often including the Near East and China , along tropical regions.
David photographing tea cultivation in
Zhejiang, Sept. 2010

Several colleagues have written to express their gratitude to and memories of David. Andy Fairbairn points that he was “ great advocate for our work and was a major influence on taking archaeobotany from a minor sideshow to a discipline in its own right”. Keith Dobney recalls “some rocking seminars with him and others on domestication.Ehud Weiss remembers him as influential teaching, “amazed by his knowledge”. Several more have written to me about how he was inspirational on their work.

Please do leave further memories and observations in the comments on this blog.

I will append some addition photos below. Feel free to submit others.

Visiting the Harvard arboretum in Boston (2008): Dorian Fuller, Ksenija Borojevic, David Harris

At the excavation of the Liangzhu city (ca. 2500 BC) wall, outside Hangzhou: Liu Bin, Zheng Yunfei, Qin Ling, Helen Harris, David Harris (Aug/Sept. 2010).
Peking University archaeologist Ling Qin discussing Liangzhu ceramics with David Harris and Helen Harris (Aug/Sept. 2010)
Visiting Hemudu archaeological site museum, Aug. 2010: DQ Fuller, Ling Qin, Helen and David Harris.

Victor Paz, Lewis Binford, Dorian Fuller, David Harris, Lazslo Torok (Cambridge, 1998).

David Harris in conversation with Prof. Barbara Pickersgill and Dr. Mark Nesbitt, Linnean Society of London 2006.

Gordon Hillman, Mary Anne Murray, David Harris, and Sue Colledge, in office 311, UCL Institute of Archaeology 1998/99.

Thursday, 14 November 2013

Origins of Rice Podcasts

Last week, before typhoon tragedies hit the Philippines, I joined about 700 geneticists and plant breeders working on rice for the Rice Genetics 7 symposium, organized by IRRI. and I was very proud to present our current archaeological picture on the origins and spread of rice in Asia to a packed auditorium the first morning. I also had the opportunity to take part in an IRRI radio podcast on the "Origin of Rice" for a ~5 minute version also featuring Prof Sudan McCouch go here . For the extended 14-minute version on archaeobotany try this link.

Monday, 15 July 2013

The eastern fertile crescent returns

The recent paper in Science by Riehl et al. on  the evidence for Chogah Golan has rightly garnerd wide attention (e.g. Science news; commentary by Willcox). This is a highly significant paper, which shows that the beginnings of cultivation were indeed mutlicentric within the fertile ccrescent, and it suggests that there was an independent domestication process for emmer wheat in the eastern fertile crescent in addition to that in the western fertile crescent. 

Are there surprises? Yes. The big surprise here is the emmer wheat domestication, as many have argued on biogeographical and modern genetic grounds that there should have been and eastern and western barley domestication, but this has been little considered for wheat. This is mainly because the modern distribution of wild wheats does not extend that far east and south, and thus the data from the Chogha Golan, especially the lower levels indicates that the distribution of wild wheats at the start of the Holocene/end of the Pleistocene was indeed different and more extensive than modern wild wheats. This further implies that some starts to cultivation and domestication events could have drawn on wild population that are extirpated today and therefore are not reflected in modern wild germplasm collections. Modern collection used in genetic studies are only a fragmentary representation of the past, although geneticists often fall into the trap of assuming that good wild sampling in the modern day means they have captured the wild diversity from which domestication began.

What this what we/ I suspected? Yes. I am one of a number of scholars who have been arguing for a multicentric process of parallel starts to cultivation and parallel, and protracted, domestication processes around the Fertile Crescent, i.e. De-centering the Fertile Crescent. Mostly we have argued this on contrasts between the Southwest and the north/central fertile crescent and the contrasts between morphological diversity in archaeological samples and that in modern germplasm. As the authors here note with their triticoids, they are dealing with a wild wheat type not well represented in modern collections; this is equally true of early domesticated wheats in Syria/Anatolia and even in Neolithic Europe. In the Neolithic there are extinct genetic lineages, that are morphologically distinct, that are not found in modern landraces. In other words there are several lost crops of early agriculture. 

Were things really synchronous? This remains a little unclear. The lower levels seems to have pre-domestication cultivation of barley and lentil and lost wild wheat in the equivalent of PPNA/ EPPNB time periods-- this is indeed the same period that we see this in Jordan, Israel, north and south Syria. However in the Chogha Golan there is then a break and a large minority of domesticated type emmer appears. But this is mainly in the Late PPNB (ca. 7800 BC)! By this period domesticated crops are well established at higher frequencies (usually 60-70% non-shattering spikelet bases) in western fertile crescent assemblages (mainly of einkorn wheat or barley). Emmer at Tell Aswad in Syria is ~23% non-shattering at 8300 BC and at Tell el-Kherkh in NW Syria it is 44% at ca. 8400 BC. This evolution of non-shattering (a key domestication trait) appears  slightly ahead in the west. This could mean the that 25%-domesticated assemblage at upper Chogha Golan has spread from early cultivated population elsewhere that were undergoing the gradual selection for non-shattering, or it could indicate a local process, maybe not at Chogha Golan, but nearby that simply got started a bit later. 

I would note in passing, that there was one previous suggestion of eastern emmer domestication, many years ago by Hans Helbaek in the 1960s based on rather poor samples collected by the Braidwood expedition at Jarmo in Iraqi Kurdistan in the 1950s, in which Helbaek reported intermediate types and mixtures of wild and domesticated emmer. These data were never quantified nor fully published but would potentially fit with the Chogha Golan finds. So a return to Jarmo may yet have some important archaeobotanical contributions to make.

On the whole, however, these new data offer strong support from a new dataset and a different research group for what I have been championing as a paradigm shift in agricultural origins research. From the paradigm of a rapid and singular agricultural revolution to a paradigm of protraction and entanglement that was messy and non-centric. (See, e.g. refs 2 and 19 cited by Riehl). 

Tuesday, 7 May 2013

Used Planet

Last week saw the publication of "Used planet: a global history" in PNAS [pdf] in which I teamed up with some land use and palaeoenvironmental modellers to offer an alternative synthesis of the evidence for human environmental modification. Much of the time in studies of land use and environmental change it is assumed that major environmental change and destruction is quite new, something brought on by the industrial era in the last few hundred years. Land use models like the HYDE model illustrate this, with something that approximate the projection of modern population: land use ratios backwards to periods when very few people were around. The key authors of the original HYDE model were part of this paper, and are quick to point out the many uncertainties and flaws in the HYDE dataset and its application (as in this recent paper). This is illustrated by the graph on the left (above) with most of the transformed land (in light purple) only dating to the past few centuries). By contrast in a model that assumes landuse intensification fewer people used land more extensively and only more intensively as rising population forced them to (the right hand charts above). Comparing maps of these different models, makes it look like "two different planets"  (to quote the blog of lead author Erle Ellis). Whereas archaeologists and anthropologists have debating and modifying Boserup's intensification concept or the notion of "agricultural involution" of Geertz for decades, this seems to have came rather late to global climate and land use modelling studies. Intensification in the use of all sorts of things has been a hallmark of human prehistory, from the broad spectrum revolution, the development of post-harvest intensification, in the use of grinding stone and other cook techniques (explored elegantly by Wollstonecroft 2011), the development of pre-harvest intensification (i.e. cultivation), improved yields through the evolution of domestication traits (with its own new labour demands, a kind of intensification too, see, e.g. my "domestication as innovation" paper), and agricultural intensification as it is normally defined (on which, see Morrison 1994). That our review of these two planets, which fairly clearly comes out in favour of one in which transformations by people are old and intensification processes are long-term, catches some sort of zeitgeist, is suggested both by the press coverage of this paper in New Scientist, Scientific American and The, and a session devoted to the same theme at last months SAA (summarized by Michael Balter). Of interest is that the latter two take the younger "impact" date of 3000 years, while the former takes 5000 years (I guess on my suggestion). One of the things that came up in discussions that lead to this coverage is what kind of impacts were there and when should we put the start of the "Anthropocene." 

From Early Holocene impacts to the Anthropocene

Should we replace "Holocene" with "Anthropocene"? Some might tend towards this view, since the start of Holocene is afterall when cultivation began, i.e. human "niche construction" intensified. My own view was that while that was a watershed in human behaviour, it was a long time before cultivation got underway in most parts of the world, or even in those early centres, before it developed into true agriculture, cultivation at the scale that impacted landscapes and made economies that were basically dependent on domesticates, leaving little subsistence space or time for wild foods. Early impacts were not early Holocene but notably middle Holocene from around 6000 BC-1000 BC, and with increasing intensity.

To the put the early impacts into chronological perspective, I would make the following points. 8000 years ago represents the approximate point at which agriculture was established and agriculturally-supported permanent villages appeared in several parts of the world. This is the period of the first villages in China, focused on millet cultivation and with domesticated pigs on the North Chinese loess plateau and the Yellow river valley. This appear in several places from Gansu to Hebei to inner Mongolia. By this period there is clear evidence fo established cultivation of domesticated maize and squash in southern Mexico, and various crops being farmed on the northwest coast of Peru, peanuts among them, and these had there origins in Amzonia east of the Andes. In West Asia this is the period of well-integrated agroo-pastoral systems with a whole suite of crops (wheat, barley, flax, pea, lentil) and animals (cow, goat, sheep horse). This period (9000-8000 years ago) see the rise of not just permanent villages around the Near East but large "mega-sites", for example Catal Hoyuk in central Turkey, which supported permanent population in the 1000s (~6000 is one estimate of site's size). This may not sound big in modern terms, but when you consider that hunter-gather bands are on the scale of 30-40, with large seasonal gatherings at maybe twice or 3 times that at most (i.e. there were unlikely to ever be more than 100 people in one place at one time for even for a seasonal festival for the 150,000 or so years of Homo sapiens history prior to that), then a few 1000 people living together in one place, supported by local agriculture, is a big difference. 9000-8000 years ago is when farming started to spread from the Near East reaching Turkmentistan, Pakistan in the east by 8000 (which big permanent villages established in those areas) and reaching in SW Europe (Greece, and Balkans. The establishment of agriculture on several continents means sustained transformations of local landscapes and ecosystems. Of interest is that this roughly the time point at which some, such as Bill Ruddiman, have inferred that global carbon-dioxide level just start to divert from the expected interglacial trend (see his recent Earth & Planetary Sciences review paper and his Real Climate blog post). This lends extra importance to the 8000 BP landmark. Our paper is not about the greenhouse gas story, which involves lots of complicated factors of the carbon cycle, but we are certainly with Ruddiman in as much as one needs to factor human activities into the equation at that time when considering global carbon issues since 8000 years ago.

Another landmark for me is in the 5000 BP sort of timeframe. This is the period which sees the beginning of tropical savannah farmng, in subsaharan  Africa, inner India, also the central and eastern USA, mainland SE Asia. This sees the major spread of rice out of China and into SE Asia (see my previous blog), and the land area in the Old World (Africa and Asia) that support pastoralism (sheep, goat, cattle) doubling. This period sees the spread of agriculture with llama-keeping to high elevantions in the Andes, and by about 4500 BP the establishment of maize-beans-squash farming in the American southwest. In these more marginal environments the impact of early farming on erosion and local flora may have been more severe than in naturally better-watered regions. In the established agricultural centres (Mesopotamia, Egypt, the Yellow River, southern Mexico) this is the period in which the urbanism get establish (slightly later in Mexico perhaps) with all sorts of new demands on agricultural intensification and specialized production to support urban populations that do not carry out their own subsistence. The rise of major textile and metal industries at this time, especially well documented in Mesopotamia and Egypt, means larger herd of sheep that were not for eating, land for flax that was not for eating, and increase wood fuel demands for bronze furnaces (and new materials like Faience or in China proto-porcelains). Bronze is a bit later in China and SE Asia (after 4000-3500 years ago), but still falls into this time horizon generally. There is a new scale in deforestation to go along with the establishment of agriculture on all continents and subcontinent (except Australia or the polar regions). In Ruddiman's Greenhouse gas story this period is when global methane is meant to diverge from expected interglacial trends. In other words after 5000 BP both the greenhouse gases have started to look unnatural. He has hypothesized that this was to do with the spread of wet rice, and elsewhere (in a Holocene paper) I have argued that one also must count the cattle which spread like wildfire through the tropical savannahs of Africa, India and perhaps SE Asia at this time (see previous blog). This is also roughly the dairying revolution in Europe, not when people first used a bit of milk, but when people began to herd cattle to specialize in milk production (and European people evolved adult lactase enzymes): this may have also been a upturn in animal herd density. How human activities translate into greenhouse gases is complicated, because of interacting carbon sinks and sources, and not the point of the "Used Planet" paper, but the implication of out paper is that human activities should not be ruled as a contributing to global processes

By 3000 BP or so it is hard to deny human impacts, although I would put the significant shift earlier. In archaeological terms 3000 BP roughly corresponds to the Iron Age. The thing about Iron is that is much more egalitarian than copper alloys, in as much as Iron ores are really widespread and found in all regions. Mesopotamia had import copper from Oman or distant parts of Turkey, and time from Afghanistan. Africa south of Egypt and Nubia never really had a bronze age, nor did southern India, but they all took to Iron because iron ores were available. Everybody had iron ore on their doorstep. But iron smelting requires twice as much wood fuel (at least) as copper. One set of wood fuel just to turn wood into charcoal, and then charcoal represents a second set. So a upturn in wood demands and deforestation. There is no Iron Age in the Americas but Peruvian and Mexican metallurgy (copper, gold) are full swing by this time. The other thing about the centuries after 3000 BP is the upscaling and cities and the first empires. Think Assyrians, followed by Persians. The Qin emperor of China may not unify China until the 3rd c. BC but he comes at the end of process of expansionary attempts by various rulers ("The Warring States", etc). This is the era of Maya pre-classic (in southern Guatemala) and Olmecs (on the Gulf coast of southern Mexico), which represent first urban-like communities and kingdoms in Mesoamerica. In South America this period sees the arrival of farming on the shore of Lake Titicaca (which was to become a focus of intensive farming and urbanism of Tiwanaku about 1000 years ago), and first big ceremonial centres, foci of dispersed but farming growing populations, at sites like Chavin du Huantar. This period sees the founding of sites that were to development into cities in the Niger river in west Africa, the earliest phases at place like Jenne-Jeno and Dia. In short, all over the work human population densities increase, proportions of the populations not engaged in their own subsistence increase (but are still a miniscule minority bu modern western standards) and technologies requiring heavy wood fuel use increase in scale and global frequency. 

Time for Big Archaeology

When I was asked by the journalist from New Scientist where I put the start of the "Anthropocene" I suggested 5000 BP. By 3000 BP there is certainly no doubt (the date chose by the headlines in other coverage). Erle I know does not want to commit to any one date for this transition, and I think we would both emphasize that there have been several step changes, often different in timing in different regions, in the relationship between human population and landuse and land transformation. These changes and landuse relationships need to be better-studied and better quantified. Archaeology, which I represent among the contributors on the PNAS paper, has a lot to contribute here. Archaeologists in a sense have been gathering such data without realizing its relevance to issues of long-term global change, and archaeologists are generally very region and period focused-- archaeologists, we might say, have their heads down holes-- with less awareness of the macro-scale and really long-term comparisons. I think that it is time for that to change, and I hope that more archaeologists will start see how their evidence can contribute to better models of long-term landuse and ecosystem management. It is time for archaeologists to become a bigger part of these discussions. 

We need to get some BIG ARCHAEOLOGY going. Then we can return to the issue of when the Anthropocene began.

Thursday, 21 February 2013

Earlier sorghum in Sudan

I have recently been made aware of a small report in Nyame Akuma on Kasala (northeast Sudan), where Italian researchers have restarted research which can be regarded as following on from the 1980s survey headed by R. Fattovich. The new work has included the study of some plant impressions in ceramics published as "Sorghum exploitation at Kasala and its environs, North Eastern Sudan in the Second and First Millennium BC" by Alemseged Beldados and Lorenzo Constantini in Nyame Akuma vol. 75. As its title indicates this study does confirm the present of Sorghum bicolor, plausibly (but not definitively) domesticated, in ceramics from the site of Mahal Teglinos and some from near by survey collections. It reports examination of 25 sherds of which 11 from Teglinos and 11 from survey have sorghum.

As many will know I have been critical of some previous sorghum identification from impressions, in particular coming out the lab in Rome (most infamously those from Oman and Yemen). As a result, in various tallies of early sorghum I have always regarded the 1980s report of Sorghum of the Kasala region survey as requiring a big question mark next to it (e.g. "The economic basis of the Qustul splinter state"). The sorghum here, at least in fig 4, looks legitimate. The suggestion that grains shape (narrow versus wide) can be used to identify both wild and domesticated sorghum is more problematic. Meroitic Umm Nuri produced very very thin but apparently domesticated sorghum (published by me in Sudan and Nubia 2004).What is really needed is clean views of spikelet bases (for wild versus domesticated hulled forms) or evidence for still attached rachillae (especially in free-threshing forms).

I now believe that sorghum is there in Kasala, dated by ceramics (Mokram group) and association to 1500-500 BC. This is important news, as it takes sorghum earlier probably than any of the find in the Nile Valley, which are mainly Meroitic, and with possibly earlier Napatan sorghum at Kawa (in Sudan and Nubian 2004). This is a relief given that it is India before this time by at least a couple of centuries, and maybe more (for an updated review of early African crops in South Asia see by papers in Nicole Boivin, either that in J. World Prehistory on Arabia, or the Etudes Ocean Indien paper [in English]).

Some of the other identifications, notably cowpea (Vigna unguiculata) reported from one impression remain unconvincing, at least as photographed, and I really cannot except them on this sort of evidence. I would also expect pulse seeds to make poor temper for pottery. While we might expect this species in this region and period, as it was in cultivation prior to 1500 BC in West Africa and had arrived in India too by this time, I'll await more convincing evidence.

It is a pity high quality imaging, especially SEMs, were not made of the casts as, then one could see finer details of morphology like characteristic hairs, etc., that really clinch an ID. (See, for example the unicellular  e.g. w&v in the images from the Essouk archaeobotanical report, also a rachis stalk which suggests it is domesticated).

Also tantalizing is the evidence for millet, Setaria, impressions in 3 sherds. As illustrated, one could also propose a Bracharia and we really need better resolution SEMs and husk comparisons to get this to species level. Nevertheless it is plausibly a fit for S. sphaceleata, which is of particular interest as the  "lost" millet of Nubia,which we have evidence for cultivation of from Napatan to Medieval times (Kawa, Qasr Ibrim, Nauri). The origins and history of this lost millet of Nubia really needs to be chased down. It has gone extinct from Nubia in the past millennium, replaced by Setaria italica.

(Thanks to Mike Brass for bringing this paper to my attention)