Sunday, 29 October 2017

Finding rice domestication in clay (new methods in archaeobotany)

One of the more exciting methodological developments in archaeobotany I have seen lately is the use of ct-scanning to look into chaff tempered ceramics and to extract in virtual terms the invisible plant remains therein. Aleese Baron, Tim Denham working with a range of colleagues have applied ct-scanning and computed tomography to produce images of rice chaff and rice spikelet bases from Neolithic sherds from three Neolithic sites in Vietnam published in Nature's Scientific Reports.
The sites are An Son, Loc Giang and Rach Nui. In all cases, conventional archaeobotanical evidence through macro-remains has been limited, although rice and millet as well as various wild taxa were reported from flotation at Rach Nui earlier this year. This makes the potential to recover plant remains from ceramic tempering quite tempting as an additional source of evidence on past plant use. As demonstrated by new evidence on sorghum domestication found in old sherds. However, while traditional we may cast impressions of those remains that are haphazardly represented on the surface, ct scanning allows full three-dimensional voids to be recovered from the interior of the ceramic fabric.
While patience and skill required to get such images is impressive, the results are breath-taking, with images of domesticated type, non-shattering rice spikelet bases pretty much as good as those found through flotation emerging (see left). It is not any surprise that these Neolithic folks in Vietnam were already dehusking fully domesticated rice and using the chaff to temper their ceramics-- this very much fits current hypotheses for the spread of fully domesticated rice into mainland southeast Asia from the end the Third Millennium BC (e.g. the recent review by Castillo in the journal Man in India). Methodologically, however, opens up the possibility for studying old ceramic collections from sites that may no longer be amenable to sampling through flotation or which lack good stratigraphy, at least so long as some ceramics are chaff tempered. This could prove quite useful for any earlier, less sedentary phases in the spread of rice, just as sherd impressions have proved so useful in Africa, right across the Sahara and sub-Sahara. Studying sherd impressions just got powerful new tool.

Thursday, 26 October 2017

Earlier Sorghum in Sudan (2017)





A few years ago I posted a blog on Earlier sorghum in Sudan highlighting the work by Alemseged Beldados and Constatini on sherd impressions from Kasala from the early Second Millennium BC. At the time I raised the question as to whether or not these impressions were wild or domesticasted. At the time I bemoaned the lack of SEMs and attention to spikelet base remains. That blog post attracted the attention of Frank Winchell (see his comments at the time), and around the same time Frank had met Michael Brass, then a PhD student at UCL. Through these interactions, online and eventually in person, we started a collaboration to re-examine ceramics that Frank has collected and studied from a site of Kasm el Girba 23, to the southwest of Kasala, from field work over 30 years ago. Frank has long been impressed by the present of a large number of apparently seed or chaff tempered ceramics in a ware type called Kharadag Plain, and through extensive examination in the UCL archaeobotany laboratory, casting impressions and SEM study, as well as re-assessing our reference material of domesticated and wild sorghum.


The results are highly significant, and have now been published in Current Anthropology. Domesticated sorghum morphologies were present much earlier than previously found, i.e before 3000 BC, more than a millennium earlier than the Kasala finds or finds in India. In addition the material represents a mix of almost equal parts morphologically wild (smooth spikelet base) and domesticated (torn rachilla). This suggests that the Kasm el Girba material is around midway in the domestication process, and by analogy with the protracted domestication now well documented for rice, wheat and barley, we should be considering this as an advanced stage of pre-domestication cultivation, and seeking the beginnings of pre-domestication cultivation sometime before 4000 BC. This has received some science journalism attention from Nature and Science News.

One of the other highly significant patterns is the Kasm el Girba faunal evidence, as previously published by Joris Peters: it represents a wild hunted savanna fauna. It lacks the evidence for sheep, goat or cattle, in contrast to the evidence for some pastoral component to the economies of the Neolithic around Khartoum from the Fifth Millennium BC at least. This calls into questions the widely accepted notion of "cattle before crops" in Africa (as per Marhsall and Hildebrand 2002). Certainly pastoralism gets established in parts of the Sahara around 6000 BC, long before any evidence for cultivation. It is also true that the earliest evidence for domestication of pearl millet, reported by Manning et al (2011), occurs alongside evidence for cattle and caprine pastoralism. But in this case we seem to see evidence for cultivation of early sorghum and sorghum domestication taking place among fairly sedentary hunter-gatherers and not their Sahelian pastoralist neighbours. This raises some exciting questions for further research in Sudan, and calls for renewed efforts in zooarchaeology and archaeobotany of the Early to Middle Holocene in northern Sudan, etc.

Wednesday, 23 September 2015

A tribute to Alice Berger, a research student lost too soon

A personal tribute from Alice’s PhD supervisors at UCL

This week we learned the sad and shocking news of Alice Berger’s passing. As Alice’s PhD supervisors at the Institute of Archaeology, UCL, we extend our deepest sympathies to her family and friends. Alice came to the Institute from the Department of Archaeology and Ancient Near Eastern Cultures at Tel Aviv University. Her Masters thesis on “Plant Economy and Ecology in Early Bronze Age Tel Bet Yerah” won the prestigious John Evans postgraduate prize, awarded by the Association for Environmental Archaeology, and her achievements were recognized by the further award of UCL’s Overseas Research Scholarship and Graduate Research Scholarship to support her PhD research.
Alice was a fiercely independent researcher of extraordinary capacity, breadth, and originality. She possessed a flair for environmental archaeology that was quite unusual, mastering techniques of botanical and zoological analysis that are often treated as isolated specialisms, and reminding us all that these are simply vehicles in a wider project of understanding the human past, and its changing relationships to the non-human world. Her doctoral project, teasing out the environmental correlates of Early Bronze Age urbanisation and migration in the southern Levant, was producing exciting results, presented by Alice at conferences around the world with a style and confidence that always rose to the surface when she spoke in public. She was deeply passionate about her research, which was attracting widespread praise and attention.
Alice was also a gifted and natural teacher, seeming happiest and calmest when instructing students. While some specialists are intellectual hoarders, Alice’s approach to knowledge was democratic to the core. She excelled as a teaching assistant at the Institute, and in the field at Tel Bet Yerah she transformed her laboratory into a centre of learning, taking pride and delight in the ability of undergraduates to identify prehistoric animal remains after just a short time in her company. Anyone who had the privilege to know or work alongside Alice will also know the struggles she faced on a daily basis, and the courage with which she confronted them. One always had the feeling that, whatever the obstacle, Alice would eventually emerge, smiling, resolute, and in search of her next challenge. Hers is a dreadful loss to our subject and our community, and we will miss her terribly.
But we also feel sure that Alice would not want our brief tribute to end on a sombre note. So we will finish with a recollection that perhaps captures something of Alice, and the intensity with which she seized life, both inside and outside the laboratory. It relates to Alice’s first encounter with the Institute in London, when she undertook Dorian’s intense short-course in archaeobotany. David Wengrow, her host at the time, recalls her coming to his office within a few days of arrival, to explain that she had suffered a concussion while attending a Rob Zombie concert. ‘But don’t worry’, she reassured him, ‘I actually find that as a result I can stare down the microscope for much longer periods of time’. May you rest in peace, dear Alice.  



Many more posts from Alice's friends and colleagues can be found on her facebook wall.

Early Rice Project symposium last week

Last week we hosted in London a symposium for the Early Rice Project, 
Investigating the evolution and impact of rice cultivation through the later prehistory of monsoon Asia. We brought in colleagues and collaborators on the archaeology of India, Southeast Asia and China, from countries across several continents, and had a success full exchange, not just on the archaeobotany of the region and new data (much of it generated at UCL through our NERC and ERC projects), but also on the stories of domesaticated fauna, our current understanding of Neolithic spread processes, Mesolithic persistence, demographic growth and the emergence of complex societies and irrigation. What is clear is that there is much new to say about rice, when it first arrived in several regions of monsoon Asia, and as it was transformed into the cornerstone species in the subsistence base of large complex societies. Nevertheless the meeting highlighted also the major gaps in empirical evidence, both geographically and chronologically. We hope to be able to pull this together for publication to further broaden out our dialogue on what we know and what we need to know. There has certainly been a rapid increase in data as the chart (below) of published, or recently counted archaeological spikelet bases indicates (from my introduction presentation)..


Some recent outputs from the Early Rice Project include publication of ancient DNA from charred rice grains from sites in Thailand and India (Castillo, Tanaka et al.), which add some flesh on the skeleton of the Proto-indica hypothesis; and publication of the first of a new generation spatial modelling of the early geography of rice, this one aimed at deducing the most like region (or regions) from which rice originated and spread, in particular the originals of early japonica rice that was so important to the Neolithic developments in China and throughout Southeast Asia (Silva et al. in PLOSone).  See also, the paper on phytoliths as a reflection of weed flora (Weisskopf et al 2014), the first of several in the pipeline that will illustrate new and more robust approaches to determining past rice ecology.

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.