Wednesday 29 April 2009

Recent Yucatan symposium

In March, a small Wenner-Gren symposium on the origins of agriculture was held in Hacienda Temezon, Yucatan. A synoptic report by the organizers (T. Doug Price & Ofer Bar-Yosef), can now be found on the Wenner-Gren website. The publication is intended to come out in early 2010.

Monday 27 April 2009

Millet Watch: Even earlier dates for Chinese Panicum

Published on-line last week in PNAS was a major new archaeobotanical study of the site of Cishan in central China, which utilized husk phytolith identification methods-- recently developed (published in PLoSone in February)-- and chemical differentiation between foxtail millet and broomcorn millet-- newly developed in this paper. Cishan is well-known site names, generally dated to sometime around 6000 BC, and regarded as type sites one of the early Neolithic cultures of northertn China. There has long been confusion over exactly what sort of millet remains were preserved there, based on the report from previous excavations in the early 1980s, of large storage pits full of 'millet' which variously been interpreted as Panicum or Setaria, but which never were studied or published within any real basis for identification (see for example the recent Cantab. review on early millets). Now this paper by Lu Houyuan and colleagues from the Institute of Geology at the Chinese Academy of Sciences, have cleared this matter up: broomcorn millet was the basic staple at Cishan, at least at its earliest period, and Setaria italica, therefore appears to be a later addition to the crop repertoire, at least in this region. Indeed, this also appears to be the case fruther west at the later Dadiwan, where Panicum cultivation, and especially consumption (by people and their dogs), goes back to 5900 BC or so (work by Barton et al., on which I blogged previously - and with a reply from Barton).

The other major bit of exciting evidence from this new Cishan study are the radiocarbon dates that put the earliest storage pits and millet at the site back to 8000-8500 BC. This would seem to push millet back about 2000 years! (Giving it an even bigger head-start, over rice, as a crop). Other dates are as late as 5500 BC, suggesting a very long (but continuous ?) occupation at Cishan. As any archaeologist will feel, the long span of time covered by the Cishan dates raises many questions about the nature of settlement, society, and site formation over this period.

This study has many strengths (especially with regards to the careful and innovative lab methodologies) but it also has a few weaknesses. These include the unstated/unquestioned assumptions about the ecology of the wild progenitor-- points I raised earlier in relation to Dadiwan-- although I tend to agree that large grain stores imply a regularly cultivated stock. There is also a lack of comparably detailed archaeological work: what is the settlement pattern and material culture that goes with these early millet cultivators and how does it change over the millennia between 8500 and 5500 BC? The latter is, of course, not a question aimed at the authors of this study, but at Chinese archaeological colleagues. Prof. Lu and colleagues have provided some powerful new tools for finding and identifying early millets, but the next step is to deploy these methods in some joint projects with archaeologists so that open excavations, ceramic and lithic toolkits can be assessed alongside the phytoliths. In short, we need more archaeobotany like this to be part of archaeological projects.

My final quibble, as is so often the case, is that we need to be cautious with use of the term 'domestication'. Was the millet at Cishan cultivated? Probably, for the reason that it was stored in large quantities as a staple food. Had it undergone morphological domestication, for non-shattering, larger grain sizes, possible changes in dormancy?... More research that links phytolith morphologies to the domestication process (selection pressures) and domestication traits is needed (this is true of most cereal crops, not just millets!). It seems unlikely that phytoliths will answer all the questions about domestication (like non-shattering). Where on the pathway to domestication was the Cishan millet, and how did it change and move along that evolutionary trajectory over the 3000 years the site was occupied? (Or are we to infer the process was all finished?) The lesson of Tianluoshan is that early crops were still evolving, and this is a protracted process that we should be able to see and track, once we develop the right tools with which to see this-- somes lesseon might be drawn from other crops like wheat and barley for which it is just becoming possible to track the mode and rate of domestication [Ann. Bot. paper]. These new phytolith and chemical criteria, developed in this Cishan study, are an important part of the tool kit that we need for domestication studies in millets. We need more data and integration together with additional methods (macro-remains, isotopes). So the fun begins, the quest for millet domestication.

Studies inspired by Gordon Hillman

Gordon Hillman made a lasting impression on archaeobotany, both through his research and publications, and especially through his teaching. The study of hunter-gatherer archaeobotany (especially in Europe and the Near East), the origins of agriculture, and crop-processing (which he pioneered), would not be the same. In a few months a collection of papers in honour of him by former students, colleagues and those inspired by his work (like myself) will be published by Oxbow Books. Information on contents, are below. [This book was published at the end of July 2009 & presented to Gordon on 2 August]

From Foragers to Farmers; papers in honour of Gordon C. Hillman,
edited by Andrew Fairbairn & Ehud Weiss

contents list:
1. Gordon Hillman and the development of archaeobotany at and beyond the London Institute of Archaeology (David R. Harris) 2. Gordon Hillman, Abu Hureyra and the development of agriculture (Andrew M. T. Moore) 3. Gordon Hillman’s pioneering influence on Near Eastern archaeobotany, a personal appraisal (George Willcox)

THEORY AND METHOD 4. On the potential for spring sowing in theancient Near East (Mark A Blumler and Giles J. Waines) 5. Domestication and the dialectic: Archaeobotany and the future of the Neolithic Revolution in the Near East (Joy McCorriston) 6. Agriculture and the development of complex societies: An archaeobotanical agenda (Dorian Q Fuller and Chris J Stevens) 7. Dormancy and the plough: Weed seed biology as an indicator of agrarian change in the first millennium AD (Martin Jones)

ETHNOBOTANY AND EXPERIMENT 8. Wild plant foods: Routine dietary supplements or famine foods? (F├╝sun Ertug) 9. Acorns as food in southeast Turkey: Implications for prehistoric subsistence in Southwest Asia (Sarah Mason and Mark Nesbitt) 10. Water chestnuts (Trapa natans L.) as controversial plants: Botanical, ethno-historical and archaeological evidence (Ksenija Borojevic) 11. Evidence of domestication in the Old World grain legumes (Ann Butler) 12. Einkorn (Triticum monococcum L.) cultivation in mountain communities of the western Rif (Morocco): An ethnoarchaeological project (Leonor Pena- Chocarro, Lydia Zapata et al.) 13. The importance and antiquity of frikkeh: A simple snack or a socio-economic indicator of decline and prosperity in the ancient Near East? (Amr Al-Azm) 14. The doum palm (Hyphaene thebaica) in South Arabia: Past and present (Dominique de Moulins and Carl Phillips) 15. Harvesting experiments on the clonal helophyte sea club-rush (Bolboschoenus maritimus (L.) Palla): An approach to identifying variables that may have influenced hunter- gatherer resource selection in Late Pleistocene Southwest Asia.(Michele Wollstonecroft) 16. Aspects of the archaeology of the Irish keyhole- shaped corn drying kiln with particular reference to archaeobotanical studies and archaeological experiments (Mick Monk and Ellen Kelleher)

ARCHAEOBOTANY 17. Glimpsing into a hut: Economy and Society of Ohalo II's inhabitants (Ehud Weiss) 18. Reconstruction of local woodland vegetation and use of firewood at two Epipalaeolithic cave sites in southwest Anatolia (Turkey) (Daniele Martinoli) 19. Vegetation and subsistence of the Epipalaeolithic in Dakhleh Oasis, Egypt: Charcoal and macro-remains from Masara sites (Ursula Thanheiser) 20. The uses of Eryngium yuccifolium by Native American people (Maria Scott Standifer et al.) 21. Bananas: Towards a revised prehistory (Jean Kennedy) 22. The advance of agriculture in the coastal zone of East Asia (Elena Sergusheva and Yury Vostretsov) 23. Knossos, Crete: Invaders, “sea goers”, or previously “invisible”, the Neolithic plant economy appears fully-fledged in 9,000 B.P. (Anaya Sarpaki) 24. Reconstructing the ear morphology of ancient small-grain wheat (Triticum turgidum ssp. parvicoccum) (Mordachi Kislev) 25. The Khalub-tree in Mesopotamia: Myth or Reality (Naomi Miller and Alhena Gadotti) 26. The archaeobotany of cotton (Gossypium sp. L) in Egypt and Nubia with special reference to Qasr Ibrim, Egyptian Nubia (Alan Clapham and Peter Rowly -Conwy) 27. Questions of continuity: Fodder and fuel use in Bronze Age Egypt (Mary Anne Murray) 28. Food and culture: the plant foods from Roman and Islamic Quseir, Egypt (Marijke van der Veen, Jacob Morales, Alison Cox)

Friday 24 April 2009

African Archaeobotany 2009

Although I will sadly miss it myself, I want to note the link to the webpage of the upcomming International Workshop for Africa Archaeobotany 6 in Cairo this summer. I have finally updated the African archaeobotany links on the IWAA website, both to point to the new website, but also some resources that have come to my attention recently, including PROTA, which makes available the text of the all the species which have been written up and published in the Plant Resources of Tropical Africa project, and the Kyoto University based AFLORA, which is a database of African Ethonobotany. It appears to be particularly rich for Pygmy and Bushmen groups.

Monday 20 April 2009

Flotation in China

Just to note that I have revised my account of early flotation in China, in an attempt to be more accurate, but remain brief. It appears that in addition to efforts by Gary Crawford and others involved in the early Chinese-American collaborative projects (which have sadly, still produced little in the way of published reports !), that the Chinese archaeologist Xiong Haitang observed flotation  whilein Japan visiting Nagoya University, and published a Chinese account of the technique and its usefulness for environmental remains in general (includung fish bones and molluscs) in the journal Nongye Kaogu in 1989. This inspired its application at Lilou in 1992 described by Wu, Yaoli and Chen, Xingcan in the Chinese journal Wenwu Tiandin 1992.

Thursday 16 April 2009

Portable Flotation

I remain a fan of the simple bucket, but I admit it probably requires more finesse to be relaible than a good flotation machine. (Machines are also a good sign of archaeological commitment to archaeobotany!) I have recently been supplied with photos of two portable flotation machine designs, one used at Dadiwan in China
 has been added to the base of the Chinese Flotation Machine webpage, and the other from the Belgrade Museum has been added to the base of the Serbian page. Thanks to Loukas Barton and Dragana Filipovic for brining these to my attention

Wednesday 15 April 2009

African Archaeobotany watch: the small matter of tef

For those who like to generalize, it is often suggested that early farmers chose those grasses in their environment that had the largest seeds (e.g. in Diamond's Guns, Germs and Steel), but if you want an exception, look to the Ethiopian "millet" tef [it is as much a "millet" as Finger millet, as both are Eragrostidae not Panicoids, the true "millet-grasses"]. It has by far the smallest grains of any cereal little different in size from poppy seeds when judged by the naked eye [it's length is around 1-1.5 mm and its breadth about 0.5 mm]. While domesticated cereals tend to evolve bigger grains than their wild ancestors, in Eragrostic tef this is only very marginally the case. In a recent exhaustive study published in Economic Botany Dec. 2008, the archaeobotanist Cathy D'Andrea lays out what we know, including much important new archaeobotanical data of her own. The article includes extensive data from carbonization experiments on modern wild and domesticated Eragrostis, a review of the Axumite and pre-Axumite agriculture of Ethiopia (with the continuing problems of whether indigenous crops pre-dated the introduced wheat, barley and flax; and how much earlier than 1000 BC agriculture got started in Ethiopia). From the point of view of domestication process, I note a few points from her discussion.
  • Tef has only partly lost grain shattering; while it is apparently reduced it remains a problem with mature crops (much as is true of sesame). The fact that this 'semi-domesticated' state has persisted for at least 2500-3000 years should be a warning to those pondering domestication processes: non-shattering need not evolve (either rapdily or in absolute terms) for a crop to be successfully cultivated and a persistant part of subsistence. Is there is model here for wheat, barley, rice or other millets during the enigmatic era of 'pre domestication cultivation'?

  • The lack of clear early selection for grain size increase also attracts discussion. In part this might be accounted for by increase in grain number. Yield is a combination of both factors. She suggests that lack of intensive tillage may have operated against selection here. As a proponent for a tillage-grain size increase link I, of course, am prone to agree (see my Ann Bot paper). But importantly she attributes this to a concern for lodging, in which tall plants fall over under their own weight, or the weight of their grain, reducing yields and harvestibility. Apparently lodging is a big problem in tef, and made worse when soils are heavily tilled. This raises interesting comparative questions about other crops, such as to what extent similar concerns might have played a role early in cultivation. Most domesticated cereals have rather thicker culms than their wild progenitors; they are also often taller and straighter. Wild rices, and I reckon primitive cultivars, were spreading and thin-stalked. Operating against the development of erect forms may have been concerns with lodging, at least until thicker stalks evolved, and in some contexts this may have also operated against the trend towards larger grains, and helped to contribute to the vast variability in grain size one encounters across archaeological rices.

  • D'Andrea points to the domesticated Digitaria spp. of west Africa (iburu and fonio) as possibly following a similar domestication pathway with similar constraints. Is there is more generalizable pathway here, perhaps applicable to Brachiaria spp. and Paspalum scrobiculatum as well, in which think culms that threaten lodging operate againt major increases in grain size and grain density, but not overall grain number which is dispersed across the panicle? This might also be relevant for some Panicum spp. (sumatrense, sonoram; but I guess not P. miliaceum)?
Much food for thought and grist for the mill in this paper, in addition to being a nice contribution to the under-archaeobotanized East Africa.

Tianluoshan rice in the News

On our recent publication on the rice spikelet bases from Tianluoshan, the following sources picked it up as a news item.

From the China Daily Newspaper: "Fresh proof of China being the Cradle of Rice"

The Science News feature by Michael Balter (from Science 20 March 2009): "Recipe for rice may have taken Millennia"

The CBC (Canadian Radio) program, Quirks & Quarks, featured some discussion on rice domestication and the Tianluoshan paper, in its 11 April 2009 broadcast. A podcast is available.

Summary and comments on the Agricultural Biodiversity Weblog.

The full text of the article can be accessed free through the link on Dorian Fuller's publication list on the his UCL staff profile. For an introduction to the project see this initial Tianluoshan project page, and for new directions in rice research, visit the brief description of my NERC  rice project.

Millet Watch: Cantab reviews on early millets in China & Europe

Xinyi Liu, Hunt and MK Jones have published an assessment of the (quite limited) data for early North Chinese millets in Antiquity, in which they argue for a shift away from the river valleys of early civilization to the 'hilly flanks' in the search for domestication. Probably right but seems quite a lag-time to be re-inspired by Braidwood!

This Cambridge archaeobotany group have also provided a recent review of ~5000 BC and earlier millets reported from across Eurasia in a recent Vegetation History and Archaeobotany [open access]. A useful compilation in particular as it has made reference to hard to obtain sources published in Chinese and Russian. I remain unconvinced of Jones' (2004) hypothesis that Panicum miliaceum was an early Neolithic crop dispersal from East Asia to Europe. The Early European data is quite thin on the ground and may well represent weedy/wild material, or a separate origin as millet crept into East European cultivation. Striking is the evidence for a late (i.e. Bronze Age dispersal out of China) of Setaria italica and other Chinese domesticates.

Here is the link to their "East-West Millet Project" website.

African archaeobotany watch: new data on the First Millennium BC 'crisis'

In the latest issue of Quaternary Research (May 2009), Ngomanda, Katarina Neumann and colleagues report new pollen data from Cameroun which address the nature of vegetation changes between the end of the Second Millennium BC and the end of the First Millennium BC, a period when archaeological settlements are thin on the ground in sub-Saharan West Africa. Elsewhere Neumann and others(Breunig) have written on the apparent crisis in which early agricultural settlements of the West African Neolithic (based on pearl millet agriculture) were abandoned and sedentary agricultural settlement (often with a different, broader agricultural package) re-emerged in the later First Millennium BC. In this paper they suggest some possible reasons. I have been struck by a somewhat parallel abandoment phase in peninsular (savanna) India between ca, 1200 and 600/400 BC, i.e. the Jorwe collapse in the North Deccan and the end of Southern Neolithic. Could there have been a parallel kind of ecological shift involved?

Tuesday 14 April 2009

New World Archaeobotany Watch: early dates for maize and other centres

Rio Balsas Maize, 6700 BC. New data pushes back maize earlier in Mexico than outside mexico and in the right part of Mexico, but notice that it is already domesticated, which means the beginnings of cultivation are earlier. This has a ScienceNOW post by Michael Balter, and the artilce by Piperno et al in PNAS (March 2009), "Starch grain and phytolith evidence for early ninth millennium B.P. maize from the Central Balsas River Valley, Mexico," needs to be read with the Ranere et al PNAS paper in the volume on the archaeological context., "The cultural and chronological context of early Holocene maize and squash domestication in the Central Balsas River Valley, Mexico".

North Peruvian Early Agriculture. Starch grain data from human teeth confirms the consumption og Phaseolus beans, squach (Cucurbita cf. moschata) and peanut at ca. 6000 BC, as reported in the recent (Dec 2008) PNAS paper by Piperno and Dillehay. The confirms the evidence of macrobotanical remains reported by Dillehay et al in 2007 in Science, in which AMS dates pushed cultivation in this region back to 7000-8000 BC. While all this may be suggestive of this area being an early focus of agriculture (and it featured as possible centre 3c in the recent Purugganan and Fuller map in a Nature review), some of this crops (certainly peanut) and arguably squash (?) were probably not native this particular region, implying that their start to cultivation was somewhere else and even earlier!

North American Early Crops. The latest installment on the evidence for indigenous domesticates of the later Mid-Holocene of Eastern North America is represented by the Smith and Yarnell report on the Riverton seed assemblage in PNAS 7 April 2009, which includes some of the classic 'lost crops' of North America such as Hordeum pusillium and Chenopodium berlanderi

Recent South Asian Archaeobotany

Kanmer. The joint excavations of the Kharakwal and the Osada Project of RIHN (Kyoto). Two preliminary reports have been published in the occassional papers series of the project (nos. 2, [2007], and 5, [2008])-- difficult to obtain publications. Both include some archaeobotanical data (lists of species present by samples) provided from analysis by Pokharia in Lucknos.

Ojiyana. Anil Pokharia reports the plant remains from Ojiyana a Chalcolithic site of the Banas [Ahar] Tradition in Rajasthan, in Current Science March 2008 [pdf]. As seems to be emerging as a pattern with sites dated at BS, two dates are anamolously early (both ca. 5000 BC) and out of stratigraphic sequence with two dates in the 1750-1400 cal. BC range, which is more in keeping with the materail cultural of the site (Ahar/Banas pottery and I presume copper artefacts). In keeping with the tradition of the Lucknow school of archaeobotany, quantification is assiduously avoided, but presence/absence data is provided only (for 29 samples). Some metrical data is indicated for the identified but as broad ranges, so no sample size or standard deviation can be calculated. Of note are the presence (in one sample each) or finger, sorghum and safflower. Sesame is rather more widespread. Naked wheat and barley (both hulled and naked) and rice are near ubiquitous, as is "Setaria sp./ Setaria italica"-- how much (if any) of the latter might be Brachiaria ramosa deserves consideration. Nevertheless a valuable contribution in as much as it provide a diverse suite of species in a region poorly sampled archaeobotanically [the only other well-samples site is Deccan College's Balathal].

Tokwa.  In Current Science in January 2008, Anil Pokharia reported archaeobotanical evidence from flotation at this excavation by Allahabad University between 2001 and 2003 [some small samples collected by the team in 2000 came to London for analysis by Emma Harvey & Fuller]. As seems to be emerging as a pattern with sites dated at BS, one date is anamolously early (ca. 580 BC) and out of stratigraphic sequence with two dates in the 1800-1500 cal. BC range, which is more in keeping with the material culture and regional context (comparable to Mahagara and Neolithic Koldihwa down stream-- where a good series of AMS dates on crops in the PhD of Emma Harvey are consistent with the Late Neolithic 1800-1500 BC range).  Pokharia is suitably cautious about accepting the early date. In this study counts of each species are given but details on the contexts sampled, and which samples contained which species is not provided. Of note are finds of brown mustard and flax alongside the standard rice, barley, wheat triumvirate of this time/region. Two possible mis-identifications must be noted. In Fig. 3N the photographs look like a Panicum (and not a Setaria as reported!), perhaps on the small side for P. miliaceum but the broad and short shape is more suggestive of miliaceum than sumatrense, and the reported length is consistently above 1.5mm which seems big for sumatrense. The second duboius ID is the headlined find of custard apple (Annona), which we expect to be native to South America. Claims from other sites also appear dubious.  I wonder whether we might no consider some fruit in the Ebenaceae (Diospryos) and a Sapindaceae.

Bhairabdhanga/ Pakhanna. Of interest is this unexpected archaeobotanical report from a new lab (or a lab not normally doing archaeobotany), which represents really the first archaeobotany in West Bengal. Authors, Ghosh et al., from the Botany Dept. of Calcutta University reported this in the Chinese edited but English Journal of Integrative Plant Biology in June 2006. The site is apparently Chalcolithic to Iron Age and Early Historic and said to be "in the Bhairabdhanga area of Pakhanna" (at Lat. and Long. that don't quite fit the described location). The only species reported are brown mustard, rice and urd bean, so I presume a large scale flotation program was not part of the project. Withouth stratigraphic details of the samples, they float between an early C14 date of ca. 1600 BC  (but with gross 400 yr error bars, putting it anywhere between 2000 and 1000 BC!) and two others of around AD 0. Still some new, but not surprising, data from a blank region. Lets hope it is just the beginning of archaeobotany in this region. They also report pollen data from the site, but this aren't very informative. The reported presence of Tamarindus  is of note. (but how confident can we be in genus/species level pollen ID in the tree legumes?)

Areca nuts. Also of note is the useful, critical review on the history the Areca palm and Areca chewing by Thomas Zombroich, published in the Electronic Journal of Indian Medicine.

Monday 13 April 2009

Rice watch: some recent genetics

Some recent articles on rice genetics that bear closer reading, vis-a-vis the evolution of the domestication syndrome and diversification as rice spread in prehistory.

Hagiwara et al (2009) in Molecular Ecology, report on "Diversification in Flowering-time genes in wild and cultivated rice".

Takahashi et al (2009) in PNAS, also report on Flowering time genes in rice

Izawa et al. (2009) "What DNA Changes tell us about rice domestication", the latest of many reviews on the genetics of rice domestication in recent years. Published in Current Opinion in Plant Biology. It continues to promote the hypothesis of stealth origins of rice somwhere in uncivilizaed Island Southeast Asia. (more comments on this some other time, but see the Fuller & Sato letter to Nature Genetics last November).

A new 'yield enhancing gene' dep1 has been reported in Nature Genetics. Here is a short report from the China Daily newspaper.

Grillo et al (2009) have published a discussion of the "Genetic Architecture... of Oryza nivara" representing the latest output of Tao Sang's lab in Michegan, generally a source of useful insights. The bibliography includes no references in archaeobotany.

A Hokkaido research group (Ariyaratne et al) have reported another gene ( rcn 4) involved in control of axillary branching in rice architecture in Plant Science issue for June 2009.

Rice Watch: Rice, methane and an early start to global warming

Last July, Bill Ruddiman and Chinese colleagues from the Institute of Geology published a artcile looking at the correlation between a compilation of archaeological evidence for rice in China and the divergence of global methane levels, towards higher levels, from the decrease that is expected based on previous interglacial patterns. This article appeared in Quaternary Science Reviews, and attracted a news note in Science "Was China an Early Emitter", but this has important implications for archaeologist, or rather it highlights the importance of the archaeology of early agriculture to wider issues to do global climate change. Below are my first reactions at the time of publication:  

This is an important and compelling study, and represents the first attempt to ground truth that hypothesis of major prehistoric anthropogenic methane production may be linked to intensive rice cultivation. It is a clear indication of the importance of long-term history to better predictive modelling, and the role that archaeology can play in contributing to a more nuanced understanding of the human-ecosystem feedbacks in the long-term. I think it points towards a future of increasing cross-disciplinary research by palaeoclimatologists, climate modellers and archaeologists. I see my own research agenda as moving in this direction, and I put in a research grant on this topic (in June 2008) which has now been funded by NERC and starts in 2009. Prof. Ruddiman is acting as an international project partner on this grant, with a role of identifying the cross-disciplinary implication for palaeoclimatic studies. My recent participation at the Dec 2008 meeting of the American Geophysical Union, with a session on Holocene CO2 and Methane, is also representative of this growing need for increased communication and synergy between environmental archaeology, palaeoclimatology, and climate-modelling [abstract of poster here].

The overall trend that they find is that the spread of rice in China is in agreement with predictions of Ruddiman’s hypothesis, and shows how patterns can emerge from large databases even of rather uneven data. This indicates that the archaeological record of some regions, such as China, is just reaching the critical mass of past research that allows us to see robust patterns. I would note that the archaeological record for rice is still quite uneven: most of the sites on their list were not subjected to systematic archaeobotanical sampling (flotation), nor have they been published with a full analysis of crops and weeds. Some are based on the presence of rice husk as ceramic temper (e.g. Pengtoushan—and the date of this site make its dubious whether rice was domesticated and even pre-domestication cultivation could be open to argument: see recent re-assessment by Fuller et al. 2007 Antiquity; Fuller et al. 2009 Science). Ultimately what is needed is a quantitative study of well-sampled sites, to assess the relative importance of dry-land millets (and later wheat) versus rice, and whether rice was indeed grown in wetland conditions- which should be revealed by wetland weeds (for a first stab at this kind of analysis, see paper by Fuller and Qin (2009) in World Archaeology).

In support of their hypothesis and conclusions I would offer the following observations:

1. recent work [e.g. the Tianluoshan Science paper] shows clearly the emergence rice agriculture in the 5th millennium BC (by which time a large minority of rice was morphologically domesticated, and by the end of that millennium the vast majority was), indicates that during the 5th millennium BC this early agriculture was associated with wetland weed flora with a wide range of annual sedges and small-seeded annual grasses that can be associated with paddy cultivation. Excavations by the Suzhou museum at Chuodun and Caoxieshan from near the end of the 5th millennium preserve clear fieldsystems for wetland paddy cultivation. I was in Suzhou in April 2008 to help set up the first systematic sieving and floatation program on one of their excavations, at the site of Caoxieshan , and we will soon be able to document directly what weeds were growing in those fields , and which came back to settlement areas with the harvest (as well as the proportions of immature and wild rice that remained in the population).

2. Rice starts to become much more geographically widespread from about 3000 BC. There a few sites with rice in Middle Yangshao (>3000 BC) in central China, and few more in the late Yangshap (3000-2500 BC) and many more in the Longshan (2500-1800 BC). Where full sampling has been carried out and weed flora studies, there is some indication for the presence of wetland weeds—including some of the same sedges as the Lower Yangzte sites. This is clear in our first results from the Upper Ying Valley (preliminary results were published in by Fuller & Zhang (2007) bilingual, in a Chinese monograph [access a PDF from here]), and our ongoing research at Yangshao-Longshan Baligang site in southern Henan. The overall appearance of these samples is similar that reported from the Yiluo Valley (see the Lee et al 2007 PNAS paper), although details of identification and presence of weeds has not been fully reported yet for the Yiluo. Work other sites in ongoing, including by UCL PhD students Jixiang Song and Alison Weisskopf: for a list of current UCL Archaeobotany PhD projects, see here).

3. The spread of rice outside China should also be taken into account. By 3000-2500 BC rice reached Taiwan , then by ca. 2000 BC rice had reached central Thailand, and this implies a rapid spread of rice cultivation into SE Asia. As argued by Higham, and others, this may have followed the major river valleys. If so, then it may be that early cultivation only replaced natural wild rice wetlands in the initial stages. As such it would not add to net Methane. What future research needs to show is that the total extant of marshy environments and rice paddy over the area represented by wild rice and other marshes…. For SE Asia our archaeobotanical record is still highly inadequate!

4. Also India: Rice cultivation was established in the Middle Ganges by the Third Millennium BC, and the first finds of rice in Northwest India and Pakistan, behind the range of the wild progenitor, may date to this period. In the subsequent late 2nd millennium BC and the early first millennium BC rice spread southwards, such that by 500-200 BC it is found in the far south of India in Tamil Nadu and Andhra Pradesh. It is also clear from available archaeological weed flora that Iron Age sites in the Ganges has a high diversity of wetland weed species (see paper by Fuller and Qin (2009) in World Archaeology). Thus even if it is likely that the earliest Indian rice cultivation was based on annual riverine floods and rainfall, by the time rice spread to South India wet-field systems had been developed. This accords with archaeological evidence for the development of tank irrigation systems from ca. 500 BC as rice spread south—for example from recent archaeological fieldwork by my colleague Dr. Julia Shaw in Madhya Pradesh (Sanchi area). [a paper in Asian Perspectives 2007].

5. BUT. As indicated in 3, and 4. What is needed is to test this correlations more rigourously is clear evidence that when rice was present it was being grown in wet-field (paddy) systems rather than dry-cropped, e.g. in upland indica cultivation or shifting cultivation as dry-cropped systems would not increase methane output. Although it is likely the case that most early rice in the Yangzte and Yellow basins of china was paddy systems (the earliest well-documented Yangzte systems were), it would be good to have better data on weed flora to confirm this, and quantitative archaeobotanical samples to better estimate the relative extents of millet farming vs. rice farming. Archaeobotnically we needed better developed methodologies for sampling and for analyzing samples to determine the nature of cultivation systems they represent. The kind of archaeobotanical weed flora analyses which are established in the Near East and Europe need to be developed in China and India

6. Not just rice? We also need to consider the potential of human sources other than rice. The other big potential source is the spread of livestock, especially cattle. Early in their history domestic cattle were in the Near East, Pakistan and the Sahara, and spread to parts of Europe (all by 6000/5500 BC), but herd numbers, as too human populations, are likely to have been relatively low. After 3000 BC and by ca. 1000-500 BC, the scale of things changes. Only from ca. 2500 BC onwards to you get domestic animals on sub-Saharan West Africa [e.g. new direct AMS dates from NE Mali], from which you get dispersal southwards and eastwards through central Africa. In Ethiopia, Eritrea and the horn what little data we have put the earliest cattle at 3000-2000 BC but with clear southwards dispersal to southern Africa from 2000-500 BC. Similarly livestock break the Thar Desert barrier and spread through the savannah of India after 3500 BC and mainly from 3000-2500 BC, with pastoralism (and agriculture) becoming much more widespread and dense throughout India from 2000-1000 BC. Similarly domesticated cattle only enter China in the Longshan period (2500-2000 BC) and then become widespread there. In SE Asia it is clear that cattle (mainly buffalo probably) are widespread by 500 BC. In other wards between 3000 and 500 BC you have massive increase in Old World domestic ungulate populations over much larger areas. This, together with the expansion of rice, may help to account for the accelerating trend of increasing methane level from ca. 1000 BC.

Millet Watch: new Dadiwan isotope results

The recent article in PNAS by Loukas Barton et al., on stable isotopes (of people, dogs and pigs) from the site of Dadiwan has provided new data and a new methodology for looking at the establishment of millet agriculture in China. This article attracted a nice news summary by Michael Balter on the ScienceNOw site. My first reactions below:

It remains the case that the transition to agriculture in most parts of China is poorly understood and documented with limited data. This is an important new study for a couple of reasons: it provides new evidence for agriculture in one of the north Chinese early millet cultures; also, it provide a novel methodology for thinking about the development and intensification of agriculture in terms of shifts in how people fit into the food chain.

Most clearly it shows that when Dadiwan is reoccupied in the Middle Yangshao period (from 4500 BC) that a fully developed millet dependence was developed in which humans and domesticated animals (pigs and dogs) were reliant on a millet-based staple plant food diet. As the authors argue the data suggest that this intensive, and sedentary, Yangshao millet-pig economy spread into the Dadiwan region, presumably from the East. This is significant because it highlights the fact that it was the Yangshao, which starts closer to 5000 BC in its core region, was the first expansive Neolithic agricultural tradition, in China. In other words, Yangshao spread represents the result of demographic transition towards higher levels of population growth and spread. This is happening at a period in which early rice cultivators in the Yangtze are still just collectors, settling into cultivation, and divided into smaller, regional and non-expansive cultural transitions (the Chenbeixi, Hemudu, Majiabang, Longqiuzhuang cultures). This is a smoking gun for millet agriculture developing earlier than full-fledged rice agriculture.

The earlier data from the Dadiwan culture is thinner and harder to be certain about, but is provocative. Significant are its differences from the better understood later samples: a lack of millet-fed pigs, and only a single millet-eating dog—thus implying the pigs had not been domesticated, although I would express some caution on this point: if Dadiwan people were low level food producers, then by definition millet would not have been a staple food, and their other wild staples would have been C3, and could have been shared with pigs without leaving a signature. Also, thinner and smaller occupation layers, by contrast to the impressive architectural remains from the Yangshao period (including building F901 which was a large public building)—thus implying that Dadiwan culture was less sedentary and more seasonally mobile.

It suggests that there was some millet-reliance, but the level remains problematic. This relies on two dogs having eaten a lot of millet, but we can not be sure either that millet was a regular staple for the people nor that the millet was domesticated. They infer this to be cultivation of millet, although in the absence of large archaeobotanical assemblages and morphological domestication traits, this is hard to be certain about. This difficulty is compounded by our lack of understanding of the ecology, and potential wild availability, of the wild progenitor of broomcorn millet. While the weedy Panicum ruderale provides a good model of wild morphology, what we do not have is a good model of its habitat and distribution. If it were like Panicum sumatrense, the domesticated little millet of India (e.g. Harappan Gujarat), then the wild progenitor would be a patchily distributed clump-forming grass, and large scale reliance probably would imply cultivation  for bringing large stands together. On the other hand if we take Panicum laetum, an important West Africa food that was never domesticated, as a model then we could envision extensive monospecific stands (more like wild barley or wild rice) on which hunter-gatherers could easily subsist in quantity without cultivation. How they can then conclude that millet cultivation must have started earlier somewhere else, seems something of a stretch. Nevertheless, their argued scenario seems entirely plausible, and what’s more it provides a novel food-chain perspective for looking at agricultural origins in North China. While carbon isotopes have certainly been measured on pigs and dogs before, the integration of these data as a way of getting at shifts in human and dependent animal food chains involving possible crop resources is new and important. What we need now is more of this kind of data from across North China, which is in the lucky position of being a region low in natural C-4 plants, but with major C-4 crops. [The same approach would not work in most world regions which lack such conditions or such crops!