Tuesday 30 June 2009

Rice genetics watch

A few notes on three recent additions to the library of publications of rice genetics.

1. Yamamoto et al (from Tusukuba) have publiished a review "Towards the Understanding of Complex Traits in Rice: Substantially or Superficially?" in DNA Research. This seems to be aimed at breeders and the potential of marker-assisted breeding, but it contains a useful compilation on a good range of QTLs for various domestication-related and post-domestication traits. It includes a schematic map with ~4000 qtls mapped onto the 12 chromosomes of rice, which just goes to show both how much information there is on rice, and how complex it is to understand the history of this crop when there is so much information. It is fair enough to say that most reviews have an inevitably partial view of evidence from the rice genome.

2. Panuad has published a short essay, ostensibly in honour of Darwin, on "The molecular bases of cereal domestication and the history of rice" in the French journal C. R. Biologies.It strikes me as neither particularly insightful nor up-to-date, but it is short and might of interest the less rice-savvy. Its limited reference to archaeology is rather disappointing and odd (a single Chinese article in the minor journal Nongye Kaogu), and the claim that we have less evidence from India as opposed to China because preservation is worse in tropics, is not really a fair assessment. True charred seed densities tend to be lower in India than China, but the main reason is that more Neolithic sites have been excavated in the Yangtze than in the Ganges. And even though flotation was started in India in the 1970s, perhaps 20years ahead of China, it is now being widely practiced in China as a rapid rate, whereas it is the the same 2 two labs doing flotation and analyses in India that started it in the 1970s (plus a couple of us occasional foreign visitors). Indian needs more sampling, and not to be written off as too tropical to work i, but needs more work, more workers, and more critical analysis and debate (e.g. about the nature of Lahuradewa's early rice).

3. The recent genetics paper I have seen that I am most impressed with is the study by Yamane et al (2009, in Rice) of the phylogenegentics of Hd6, one of the genes involved in regulating heading (flowering), and linked to response to photoperiod (daylength). It is clear that non-responsive plants have one of two alternate forms of the responsive (short-day) type, corresponding to two indica vs. japonica domestication pathways. It also suggests that a non-reponsive type found mainly in temperate japonica rices also derives from the wild and is found in some South Chinese wild rices. This story is entirely reminiscent of the case in barley recently brought to light by Huw Jones and colleagues.

Monday 29 June 2009

Hunter-gatherers, farmers, and monumental storage

Just a quick note of record of a new edited volume Interactions between Hunter-Gatherers and Farmers: from Prehistory to Present, edited by Ikeya, Ogawa and Mitchaell, was recently published in the series Senri Ethnological Studies by the National Museum of Ethnology in Osaka [at the time blogging, this was not yet listed on their website]. The book is entirely in English, ands arises from a session at the WAC intercongress held in Japan in 2006. It includes a mix of studies from ethnographic (2 chapters on the Agta of the Philippines, and 2 chapters on Homng farmers and Mlabari (former) hunter-gatherers in northern Thailand) and archaeological (one on Southern African by Peter Mitchell, one on the spread of farming to Guangxi, China by Tracey Lu, and 3 on Japan, and one on the archaeology of Northeastern Luzon, Philippines, exploring the long-term development of a frontier of interaction between farmers and hunter-gatherers.

I certainly haven't read all of it yet, but I would note that the short chapter on Guangxi by Lu provides a useful brief overview of the Chronology of the main excavated Neolithic sites in southwest China, the evidence for rice, millets and foraging. The Chapter by Takahashi on interdependent relationships between late Jomon 'foragers' and Yayoi paddy farmers, provides some useful material including an updated map of some 29 sites with preserved paddyfield systems dating to this period. At the centre of the book is a nearly 100-page chapter by Leo Hosoya on the symbolism of grain stores and the emergence of hierarchy in the Yayoi period, with reference to artistic evidence, settlement plan, and crop-processing (from rice grains and spikelet bases), stone harvest knives, octopus traps, and more. A rich tapestry with much to digest and much that is suggestive of the potential role of monumentalization of storage in creation of a new kind of settled community-- perhaps there are some fruitful comparisons to be made to those first permanent granaries recently found in PPNA Jordan (blogged last week).

Nubia as world centre, c. 1900-1600 BC (and a note on millet)

In the latest Norwegian Archaeological Review Hafsaas-Tsakos argues for seeing archaeological Kerma, what the Middle Kingdom Egyptians referred to as Kush, as shifting from a 'periphery' to a 'centre' in the world system at that time. (This article is not a particularly botanical one, but Nubia is always close to my heart, so how can I pass up a note on it.... for a botanical side to this note, read on). This argument is one that needs to be made, again (it has been made before by Stuart Tyson Smith). Kerma was probably the largest city in the Nile valley at its heyday (1700-1560 BC), and one of the great world cities at that time (particularly as the cities of the Indus and the Oxus had pretty much withered away by this date). The importance of Kerma a few centuries earlier is indicated by the large scale, and heavily fortified Egyptian military presence at the Second Cataract, indicated by the many Egyptian fortresses and their garrisons of the Middle Kingdom (this article includes a nice photo of one of the last, unsubmerged fortresses of Nubia at Shelfak). It seems odd that the author of this paper opines that the Egyptian presence was just about trade and did not involve control of Lower Nubia, as military towns and inscription attest to garrisons patrolling swathes of Lower Nubia (see, e.g. Joe Wegner's article in JARCE 32 (1995) 127-160)-- presumably to keep the natives in line and assure supply lines to and from Egypt. As is so often the case, economic administration and military control went hand-in-hand.

Unfortunately, this article says little about what commodities flowed from Kerma northward to make it such a centre, or what flowed from Kerma's periphery to Kerma. The importance of gold sources in the Third Cataract to Second Cataract stretch of the Nile and the Red Sea hills to the east are well-known, but I would like to flag some plant resources, of course. In her list of possible commodities, the authors notes incense. The importance of incense should be underscored. Incense was central to Egyptian temple ritual, its smoke literally helped to feed (and communicate with) the gods; and it was a required in the embalming of royal mummies. One of the forms of incense of 'ntyw, was likely frankincense or myrhh or a collective term for both. Egyptian sources indicate that this often came from the mysterious land of Punt but also flowed from Nubia. But the sources of true Frankincense (Boswellia) and myrrh (Commiphora) lie far away in Yemen, southern Oman and Somalia. Nubia was one of the point of contact then with poorly understand trades links to much further away. This centrality of incense goes back to the very beginnings of Egyptian written record, and probably before, even to the Predynastic period (see, e.g. some discussion in the recent book by David Wengrow). More than half a century ago, Henri Frankfort (The Birth of Civilization in the Ancient Near East) drew attention to the importance of incense to both early Egypt and Mesopotamia and he even speculated that traders from the two societies might have met and exchanged ideas of kingship and culture in the incense ports of Yemen-- rather a fantasy, but the importance of distantly imported incense is clear.

Hafsaas-Tsakos illustrates an imported Near Eastern juglet that probably contained fragrant olive oil or the like from a grave at Kerma period Ukma. The excavations at Ukma, published in the 1980s, provide the other tantalizing clue to Kerma's links to cultures to the east: finds of broomcorn millet (Panicum miliaceum), identified by the archaeobotanist Van Zeist (his short report in English on 'The Plant Remains' can be found in the french monograph by Vila). The importance of this lies in the fact that this species is absent from Egypt, the Levant and Mesopotamia at this time. This crop appeared in the Indus valley in the Late Harappan period, after 2000 BC (as part of a larger group of Chinese imports, see pg. 36 in my J. World Prehistory paper of 2006). There are possibly earlier finds of the mid-late Third Millennium BC reported from Yemen and eastern Iran (Tepe Yahya). Other Third Millennium find comes from further north in Central Asia. It is well-known that some African crops moved east, via sea, to India by, or just after 2000 BC; Panicum miliaceum is the one crop for which we have evidence that it moved the other way, in the world of Kerma/ Kush.

Hafsaas-Tsakos is right to put Kerma on the map of a Bronze Age world system, but such an expansion of the map needs to also include areas upstream that linked the upper Nile to Eritrea, Northern Ethiopia and the Red Sea, with its ties to the incense lands of Yemen and Dhofar. The millet from Kerma-age Ukma is the forensic clue that there were contacts, even if via down the line trade, between Kerma and these cultures to the East and South, in Yemen and to the Indo-Iranian region beyond (and from there ultimately to China where this Panicum crop originated (on its origins, see previous posts on Dadiwan and Cishan). Kerma was another centre but part of its importance lies in its links to these poorly-studied, maritime 'peripheries,' which in their own right were central to the flow of key-valued resources (like incense) with which new cultigens piggy-backed.

For more on the history & archaeology of Nubia, try this site from the expert Dr. David Edwards.

For a googlemap of many sites in Nubia, including Kerma (which you can see if you zoom in), try here.

Thursday 25 June 2009

Indian Archaeobotany watch: Lahuradewa 2008

Critical comments on the archaeobotany of Lahuradewa. The Pragdhara volume 18 (for 2008) arrived in London in the first week of June. It constitutes a special issue on the Neolithic and agricultural origins, with various reviews on other parts of the world (some I was involved in writing), and for various parts of South Asia. Perhaps the centrepiece of the issue is the latest report on Lahuradewa, excavated by the Uttar Pradesh State Department of Archaeology, directed by Rakesh Tewari. This one article from the latest Pragdhara has been made available on-line here. I have been a disbeliever in print in the past on the rice from this site (see JWP 2006, and others). Not about whether it is an important site, nor the fact that it has the earliest finds of rice from South Asia (>6000 BC), nor the earliest pottery in South Asia-- demonstrably earlier than Mehrgarh Period 2, which starts from ca. 6000 BC. But I do not think, and I now doubt even more, that the rice was domesticated. It is not even clear that it was cultivated, and is plausibly (perhaps safest interepreted as) wild gathered.

They report three new radiocarbon dates on bulk charcoal samples, which calibrate to between 8000 and 9000 BC. This means that the 50cm or so of cultural stratigraphy now has to account for 5000 years, or more, of human occupation. One has to conclude that this occupation was unlikely to have been permanent and sedentary. Importantly, they also recovered more plant remains, including more rice from the lower levels (Period 1A). Details of numbers, densities and samples from flotation are not reported. New finds also include a large ceramic fragment tempered with rice husk, and apparently some rice grains, as well as carbonized grains and spikelets. They suggest that these are domesticated on the basis of three criteria, grain size and grain ratios (using what might be termed the ‘Vishnu-Mittre index’), husk patterns, and the alleged presence of non-shattering rachises (i.e. spikelet bases).

Spikelet bases. Lets start with the last observation first.

Clear criteria for distinguishing three categories of spikelet bases, one of which is definitely of domesticated type, have been recently published (Fuller et al. Science 2009; Fuller & Qin 2008), although these publications probably post-date when this report went to press. Nevertheless, earlier work by Gill Thompson (1996; 1997) provided clear illustration of the differences between typical wild and typical domesticated spikelet bases. There are four spikelet bases shown in their Figure 16, one which is shown in close-up (Fig 16.3: above) as an example of the non-shattering type. Its long rachilla is still attached, which is a trait occassionally (but rarely!) encountered in domesticated rice, and when it does occur it usual in East Asia rices that possess multiple non-shattering alleles and it seems most common in modern varieties adapted to machine harvesting. Rather the attached rachilla is typical of rice harvested immature and green. As noted in the Lower Yangzte and China generally, spikelet bases with protruding rachillae are common in the earlier Neolithic (e.g. at Kuahuqiao and Tianluoshan) but these forms decrease over time (see Fuller et al Science 2009 [follow the link from here]), until by ca. 2000 BC in Chinese sites they are very rare (<10%).

It should be noted that both of these represent spikelets that do not appear to have broken during dehusking, and that appear thin and deformed, and are likely immature (green spikelets), which did not contain fully-formed grains. These therefore look more like green-harvested, wild rice spikelets than the threshed remains of a domestic rice harvest! But these are illustrated as the best candidates of Lahuadewa "domesticates". What is more they both have preserved awn bases. While the loss of awns is not a definitive trait of domesticated rice (many varieties, especially of tropical japonica) are awned, the presence of awns is typical of wild rices. The pictures therefore do not agree with what is stated in the text, but quite the opposite.

What about husk patterns? The basis of using husk patterns to distinguish definitively between O. nivara, O. rufipogon and O. sativa has never been clearly demonstrated or published. Quite the contrary this seems to be a non-replicable, subjective judgement. The idea is that domesticated rice is nicely ordered with square cells, and wild rice is wild and disordered. There is perhaps more of the magic of metaphors than a real method here I suspect—in any case I have never been able to see this, and one can find exceptions to this in evefy box of wild or domesticated reference material. The original inspiration of this came from the work of T. T. Chang (and was then developed by Vishnu-Mittre and his students in Lucknow), and although Chang often assigned archaeological material on the basis of husk patterns, this relied on a kind of personal magic and authority and had always had to be taken on faith. Chang borrowed this method (which was termed the SUMP method-- Susuki’s Universal Micro-Printing) from the earlier work of Katayama (1969). In the original study it is determined that there are no significant differences among the species of the sativa-complex (including rufipogon) but only between these and other wild rices (non-AA genomes rices). [Katayama, T, 1969. Botanical studies in the genus Oryza I. Morphological and anatomical investigation of glume- and leaf surface with the SUMP and histological method. Memoirs of the Faculty of Agriculture Kagoshima University 7/1, 89-117.]

I suspect that there may be some tendencies of difference between wild and domesticated spikelets husks on a popualtional level, akin to the weak tendencies in husk phytolith form, all of which are probably linked to selection for larger, fatter grains. The husk patterns therefore should show trends of gradual change overtime as grains do, but until methods of measuring and quantifying this over time are developed, this is a non-method, and seems a leap of faith too far.

Grains. This report provides a table of grain measurements, on 26 grains (although judging by the photos I wonder if some of this included attached husk, which would elevate some measures and create greater variance). It should be noted that these are all Period 1A grains with no comparison provided to later periods. Thus there is no possibility of looking for the temporal trends that one expects with domestication. In any case it is clear from examining these measurements that they break into two size groups, one is small and the other larger. This is easily illustrated in the following chart.

The smaller-grained group is comparable to non-sativa small-grained rices (e.g. O. officinalis), while the other falls into a size range that could be domesticated rice. However, when length and width measurements are taken as a scatter plot, all of these grains fall within the range defined by modern O. rufipogon and (especially) O. nivara. None of them fall into the range of domesticated rice. In order words none of them is bigger than a baseline that might be defined on the basis of modern measurements. Both the large and small groups contain ‘Vishnu-Mittre indices’ that are >2 and ~1.7, which are alleged to distinguish domesticated and wild rices. Internally this data deconstructs the usefulness of this index as a marker of domestication. Modern measurements on populations of wild domesticated rice grains certainly do not bear these indices out!

The two populations are illustrated also by scatter plot, below, where the Lahuradeva specimens (light green) are plotted over the scatter of modern populations that were plotted in Fuller et al (2007, Antiqiuty; measurements by Emma Harvey). To compare the modern and ancient grains I have added a +10% increase to the archaeological specimens as a reasonable standard correction for charring. It can be seen that the Lahuradewa grains plots nicely with Oryza nivara, while the shorter grains plot with O. granulata and O. officinalis.

Because comparison with modern rice grains may be complicated by the charring factor, I have taken two archaeological populations from India for comparison as well. Both are Early Historic (perhaps ca. 200 BC, or so) and both come from regions beyond the range of wild rice. One is from a lense of charred grains at Terr, Maharashtra, and the other is from Balathal, Rajasthan. Both were measured in London, 300 grains each. As can be seen there is considerable variation (part of that is probably due to the fact that the Balathal grains were charred as grains, whereas the Terr grains were charred as spikelets and many retain husk fragments), but these later Indian archaeological domesticated rices are clearly shifted away from the range of reference nivara and from Lahuradewa. Thus, using later archaeological rices as a baseline the larger Lahuradewa grains do not look domesticated. There is nothing beyond reasonable doubt to accuse these grains of being domesticated.

Interestingly, if these grains are compared to those from the later Neolithic in the Ganges, e.g. measured grains from Mahagara and Koldihwa, they fit nicely together. Based on recent spikelet base finds from Mahagara (1800-1600 BC), we know this rice to be domesticated. This then implies that there has been no appreciable change in grain size in rice the middle Ganges between ca. 6000 BC and ca. 1800 BC, despste being domesticated by the end of this period. This implies a very different domestication process than that in Chinese rice, in which grains get progressively larger over time as spikelet bases become non-shattering, or from wheat and barley in the Near East (see my Annals of Botany 2007 paper). Indeed, it suggests that there was hardly any selection for increasing grain size in the proto-indica cultivated in the Ganges plains (whenever cultivation began, which remains unclear). This makes sense in terms of hypothesized patterns of wild rice exploitation and minimalist wild plant food production (pre-domestication) cultivation that can be postulated for the Ganges (Fuller & Qin 2009).

This evidence is probably to be expected, given that genetic evidence indicates that several key mutations had to be introduced to proto-indica via hybridization from domesticated japonica, including sh4, for non-shattering, prog1 for erect growth habit, as well as rc for white pericarp. The real leap forward for indica rice was perhaps closer to 2000-1800 BC. Nevertheless the roots of rice cultivation were laid down earlier, but it remains unclear if this was as early of the eariest dates at Lahuradewa or whether these were periodic seasonal rice gatherers.

Diatoms. It is also suggested that the diatom assemblage from the lake sediments indicates rice growing fields. Are they suggesting, implausibly, paddy fields at this date? There is simply too little background work on the ecology of diatoms in natural wetlands where Oryza nivara, O. officinalis, etc, grow to be able to justify this statement. The diatom species that now inhabit rice fields existed before there were rice fields, and they had to come from somewhere. The habitat of wild rices seems the obvious place.

(Appendix) Some general notes on the plant assemblage. Plant taxa reported from Period 1A are: rice (reported as wild and domesticated, but see below), wild Setaria (referred to yellow foxtail millet, S. pumila), Chenopodium (referred to C. album), Coix lachryma-jobi, Artemisia sp., Silene conoidea. The Silene appear to have intact light-coloured hila (Fig. 6.8), which makes one a little concerned that they may be uncharred and intrusive, but maybe not. The rice grains as illustrated are for the most part plump and appear mature, but they are relatively short (more a feature of O. nivara than typical modrn indica), except for a few elongate, thinner grains (Fig. 6.5), at least one of which is poorly formed, which are referred to O. rufipogon; indeed they are quite plausibly rufipogon, but may also include immature grains.

Period 1B (probably 2500-2000 BC, although one wood charcoal date goes back to ca. 2800/2900 BC): apart from rice, finds include free-threshing wheat, barley, lentil, Cyperus, Coix lachryma-jobi, Artemisia, Setaria cf. pumila [Saraswat persists in the use of S. glauca, a taxonomically illegitimate name—Linnaeus’ type specimen was pearl millet not yellow foxtail!-- but lets not squabble], kodo millet (Paspalum scrobiculatum)—these are in the husk and look more likely to be wild/weedy specimens rather then the crop. The rice includes many grains referred to Oryza sativa (reasonable), some O. rufipogon (which again look like they may include immature grains: Fig. 8.8), and some O. officinalis (very short and wide), with length of ~3mm or less (Fig. 8.9). It’s a pity that these and the sativa type grains were not measured for comparison to the Period 1A material. Impressively there is some husk material of O. officinalis. This adds another site to evidence for the exploitation (or at least harvesting) of more than one rice species in the Ganges plain. Emma Harvey (in her PhD, UCL, 2006), at Mahagara and Koldihwa, Neolithic sites of the Second Millennium BC, measured husk phytoliths (the double-peaked morphotypes) and found a small proportion of husk phytoliths that fell well outside of the range of the sativa-rufipogon complex, some of which overlapped reference measurements for O. officinalis. This suggests that we should expect multiple rice species to occur on many early sites in this region.

Millet watch: Setaria genetics

Plant Physiology for January includes a short, useful review on the genetics of foxtail millet, by Doust, Kellogg, Devos and Bennetzen. From this we learn that work is underway to prepare a full genome sequence for Setaria. It usefully provides an bibliography on the phylogenetc and genetic diversity studies in Setaria italica and viridis. Most of these have concluded that Setaria italica is polyphyletic (work by Kawase, Fukunaga, etc.), although the number fo domestications versus the role of introgression with local wild populations deserves further research. It includes some discussion of architectural changes, relating to growth habit--especially apical dominance-- that were important in the domestication process of this species (and also most other cereals).

More genetic reviews on domestication

Domestication seems as hot a topic as ever, everyone is writing review papers on domestication, especially from a genetics perpsective. Often with varying degrees of ignoring, or sometimes misconveying the archaeological contribution. The paper by Brown et al in TREE late last year is a nice example of the integration of genetics and archaeology, with a focus on the Near East; there was also my own attempt (Purugganan & Fuller, in honour of Darwin). But here I would like to flag some others.

Writing recently in Plant Physiology, Sang Tao (who has done important work on finding and sequencing the sh4 domestication genes [Science 2006] which contributes to non shattering in domesticated rices-- and is shared across indica and japonica), reviews genes and mutations underlying domestication in grasses. It summarizes some of the recent functional genes reported and sequenced from rice, barley and wheat, with focus on thise genes involved in tough-rachis/ non-shattering. References to the archaeological record are absent. The general conclusion is that most domestication genes are a single mutation for a single trait, despite the fact that they are shared across diverse cultivated lines that may have different phylogenetic origins. He therefore conludes that hybridization and gene flow moved adaptive domestication genes across early cultivated populations. Indeed, this was probably a key factor in rice domestication. But contrary to Sang's assumption that non-shattering (sh4) arose in indica, I have argued (in a recent WA) it is likely to have arisen in japonica and spread to South Asia with japonica rice and other Chinese crops (and harvest knives) in the Late Harappan era (ca. 1900 BC), which represents something of a 'Chinese horizon' in northwestern South Asia.

There is a fundamental implication of a key role of hybridization in the formation of the crops we know today. Wheat researchers have long knwon this, due to polyploidy. Hexaploid bread did arise by hybridization, between a domesticated tetraploid and a wild relative. But genetics is increaaing suggesting this sort of thing was not the exception but the norm. Barley has tow distinct origins (West and East of the fertile crescent), but naked barleys of both origin share the mutation nud. The evidence indica rice clearly implicates hybridization in the making of fully domesticated indica: domestication genes that were selected by Neolithic Chinese farmers foufound their way through pollen into primitive prototype indica cultivars, which already had important adaptations to the monsoonal environment of South Asia.

This seems to raise a further question which is to what extent gene flow and hyrbdization was crucial in the earliest stages of pre-domestication cultivation? The move to accepting a protracted transition to domestication, would seem to open up this possiblility. Thus selection for large grains in one area, non-shattering in another, and erect growth in yet another seems plausible, and the extended period of pre-domestication cultivation may be necessary for this various adaptation to be brought together. Culturally this implies contact, the exchange and sharing seed stocks between communities, and in the case of rice apparently over long distances. For archaeologists who have studies things like the trade in obsidian, or the translocation of crops between African and India, in prehistory, this should come as no surprise. People were connected (even if irregularly and indirectly) over quite long distances sometimes. The evolution of cultivation systems and the crops in them was taking place in the context of interconnected communities and cultures.

Sang also raises but does not attempt the solve the historical problem that temperate japonica rices have another additional non-shattering gene (qsh1), which seems to me to be most likely selected for later as japonica cultivars were subjected to new forms of harvesting (such as basal harvesting by true sickles, which occur in China from the late 4th/ early third M. BC?) and processing.

Recent commentaries: the surge of archaeobotany

These have been a busy few months for the archaeobotany of domestication, or at least those keeping up with reading new publications. (The hard work producing the data was no doubt also busily spread out over the past few years). Since December we have seen new data on early foods in Peru, Maize in Mexico, North American crops, new thoughts on the wild food use at the start of Near Eastern domestication (Willcox et al., in The Holocene [or GCW's site]), new early evidence for Panicum miliaceum cultivation in Gansu, and then even earlier dates in central China at Cishan, and the evidence on the evoution of domesticated rice from Tianluoshan. Well-preserved granaries (the oldest) from the PPNA of Jordan when cereals were still morphologically wild but probably cultivated, have also been noted (blog here). The vast majority of these studies appeared in big impact journals (PNAS, Science), and these have of course, attracted some wisened commentaries. Here are some links to those commentaries but (without any particular further comments on them).

T. Douglas Price, commenting on Smith & Yarnell, in PNAS 106 (16): 6427-6428

Gary Crawford, commenting on Lu et al , in PNAS 106 (18): 7271-7272

Martin Jones & X. Liu in Science (8 May 2009), commenting on Tianluoshan, and early Chinese millets.

Wednesday 24 June 2009

Large granaries and pre-domestication cultivation

Pre-domestication granaries in Jordan: Kuijt & Finlayson (2009) in PNAS report preserved archaeological structures for granaries—round buildings which would have had raised wooden floors and lifespans of ca. 50 years. (This has also been reported by Michael Balter on the ScienceNOW blog.) They suggest these structures might have contained morphologically wild barley. It is a pity the archaeobotanical evidence from this site, which they elude to, is not actually presented in any detail (nor is whoever has done the work mentioned in the acknowledgements).

The quality of the excavation and the reconstruction of the architectural remains is exemplary, and leaves little doubt that raised floor granaries were constructed at Dhra (and presumable other Southern Levant sites) in the PPNA, by ca. 9200 BC. This is important evidence, since storage has more often been inferred than structurally demonstrated. They associate these structures with evidence from other sites for morphologically wild cereals (Gilgal: oats and barley; Netiv Hagdud: barley) and suggest that large-scale storage was a key part of the transition to reliance on pre-domestication cultivation. This evidence for large scale storage starting only in the PPNA seems to challenge our expectations that storage amongst hunter-gatherers ought to be a prerequisite for cultivation. Instead it appears that large-scale storage occurs alongside, or even results from (occurring after), the move to early cultivation. Undoubtedly there would have been smaller-scale precursors, such as the more limited evidence of possible Natufian silos and caching that they review.

Also of interest is the observation that storage structures move from public spaces to the inside of houses at ca. 8500 BC in the PPNB and then to special rooms by 7500 BC. This shift seems to parallel the move from early pre-domestication cultivation to more intensive cultivation as domestication traits, like non-shattering that began to increase in cereal populations from c.8500 BC and became predominant after 7500 BC (as documented for the northern Levant by Tanno & Willcox, Science 2006; and for the broader region, including Jordan, in Fuller 2007 Ann. Bot.—most of the evidence from Jordan is from S. Colledge (2001) Plant exploitation on epipalaeolithic and early neolithic sites in the Levant, BAR). This also parallels a trend in the find spots of food processing tools (grinding stones), documented by Karen Wright (UCL), which move from public spaces in the Natufian to inside houses in the PPNA-Ea. PPNB and into well-hidden back rooms by the end of the PPNB (Wright, K, 2000. The social origins of cooking and dining in early villages of western Asia, Proceedings of the Prehistoric Society 66, 89-12)

There is something of a southern Levant bias reflected in this paper, as archaeobotanical evidence for cultivation, and even archaeological evidence for possible storage structures from the Northern Levant (Syria) seems to be ignored. As reflected especially by the work of Willcox (e.g. Science 2006; the Balter News Focus piece of 2007), as well as work by Hillman and Colledge, pre-domestication cultivation is demonstrated earlier by ca. 10,000 BC at Mureybit and Qaramel. Perhaps upto 500-1000 years earlier at Abu Hureryra. Many northern sites (Mureybit, Tell Abr, Jerf el Ahmar) have large sunken floor ‘public buildings’. While these are usually regarded as structures of ritual use, they may also have been used for storing grain as suggested recently by Willcox et al. (2008) based on grain finds at Tell Abr., Vegetation History & Archaeobotany 17, p. 315). Oddly, this paper’s weakness is that it has a rather limited view of the archaeobotanical evidence, ignoring the broader macro-regional pattern for the shift to cultivation that accompanies increasing sedentism and architectural investment (both in the northern Levant/upper Euphrates area—probably first, and then the Jordan valley, a little later). It ignores archaeobotanical data from elsewhere in Jordan (e.g. publications by S. Colledge, J. Meadows). The examples it draws on are some of the least well-documented cases for pre-domestication cultivation, as they lack arable weed flora or sequences of change towards morphological domestication (by contrast to northern Levant cases), and despite some headline pieces in Science have never been published in any detail. (I nevertheless agree that they almost certainly are pre-domestication cultivation). In the end this is a nice archaeological find, with some great illustrations, but if feels somehow that they rushed to press without too much account for the archaeobotany.

Sunday 21 June 2009

Expanding African phytolith potential

An article in the latest Annals of Botany, by John Mercader et al., presents results from a study of phytoliths from modern vegetation in the forests near Lake Nisiala in Mozambique. This is an important baseline and background study, which should contribute to the potential application of phytolith analysis in archaeology and palaeoenvironmental studies in East Africa. Perhaps most importantly they have considered issues of expected relative preservation rates for different morpotypes and the patterning of phytolith assemablges representing different families, even in the absence of true species diagnostics, which should allow for inferring the vegetation type of the Miombo woodlands. Combined with a few other, widely dispersed phytoltih moprhotype studies in parts of Africa, listed below, this represents another important step on the path of developing systematic archaeobotany in sub-Saharan Africa. Other previous background studies, include:
  • Bremond L, Alexandre A, Peyron O, Guiot J. 2005. Grass water stress estimated from phytoliths in West Africa. Journal of Biogeography 32: 311–327.
  • Bremond L, Alexandre A, Wooller MJ, et al. 2008. Phytolith indices as proxies of grass subfamilies on East African tropical mountains. Global and Planetary Change 61: 209–224.
  • Runge F. 1999. The opal phytolith inventory of soils in Central Africaquantities, shapes, classification, and spectra. Review of Palaeobotany and Palynology 107: 23–53.
  • Runge F, Runge J. 1997. Opal phytoliths in East African plants and soils. In: Pinilla A, Juan-Tresseras J, Machado MJ eds. The state-of-the-art of phytoliths in soils Madrid: Centro de Ciencias Medioambientales. 71–81.

Friday 19 June 2009

Post-Doc position for the archaeobotany of rice

This is just to mirror the newlu advertised post-doc position at UCL, for candidates who are (or will be) qualified at doctoral level with expertise in the relevant research areas, to join our project 'The Identification of Arable Rice Systems in Prehistory'. The project is funded by the Natural Environment Research Council (NERC) and the appointment is for the period 1 September 2009 to 31 August 2012. In particular, we are seeking an established track record in phytolith analysis. In addition expertise in archaeobotany, palaeoenvironments or archaeology in Asia would be helpful.

The candidate with join a diverse archaeobotanical research laboratory, but will be expected to focus on phytolith analyses from Chinese archaeological and modern analogue samples. The candidate may also be involved in assisting/advising student research on Indian samples. This project will involve fieldwork in China, Cambodia, Thailand and possibly additional countries.

For further information on the overall research project, visit this web-page: http://www.ucl.ac.uk/silva/archaeology/staff/profiles/fuller/rice and for further details, contact the project leader, Dr. Dorian Q Fuller (this blogger). It would also be helpful to know your intention to apply, via email, before the closing date.

The starting salary is on Grade 7 point 29, currently £28,839 per annum plus £2,781 London Allowance per annum.

Interviews are expected to be held between 15th and 22nd July 2009.

A downloadable application form is available from the UCL Job Opportunities website or by contact Louisa Goldsmith at l.goldsmith@ucl.ac.uk, 0207 679 7503.

Please complete an applications form and send with a covering letter, full CV and two letters of reference to Louisa Goldsmith UCL Institute of Archaeology, 31-34 Gordon Square, London WC1H 0PY or by email to l.goldsmith@ucl.ac.uk.

UCL Taking Action For Equality.

The closing date for applications is Monday, 6th July 2009.