Pre-axumite wheat and barley preference: isotopic evidence

I seem to have overlooked this last year, but was excited to see some stable isotope results, (published last year in J. Arch Science by D'Andrea et al), from northern Ethiopian pre-Axumite  and Proto-Axumite sites (i.e. 800-100 BC). This indicate a strong tendency in human bones towards predominantly (but not necessarily) exclusively C-3 plant diet, i.e. such crops as wheat and barley, but with limited C-4 input. This is of interest since Sorghum, tef and finger millet, all of which might expect to have been around are C-4 plants. So the mystery deepens as to the antiquity of these taxa in agriculture in this region-- or at least they were not very important. If memory serves there is some evidence for tef from around this period (but mainly later)-- treated in some detail by D'Andrea (and blogged previously), where as the earliest finds of finger millet and Sorghum are later and Axumite Also there is an important contrast with the domestic fauna, which have a distinctly different diet form the people. Cattle and donkey have a strongly C4 signature suggesting grazing or foddering mainly from the savannah grasslands. Sheep, goat and gazelle fall in between suggesting C4 grazing mixed with browsing of C3 shrubs etc.

Gordon Hillman honoured with Feitschrift

Yesterday, Gordon Hillman had some surprise visitors, Andy Fairbairn and Ehud Wiess (and I tagged along), who presented him with a feitschrift in his honour, published last week by Oxbow Books, Several years in writing, editing, and production the volume came as pleasant surprise to Gordon.

Gordon is pcitured here with the Feitschrift in his honour and the two editors, his former students Andy Fairbairn (University of Queensland) and Ehud Weiss (of Bar-Ilan University & the Weizmann Institute of Science). This book reflects the wide impact of Gordon's research, teaching and ideas both amongst colleagues (inlcuding junior colleagues like myself), but especially amongst his students, drawn from all over the world).

In typical fashion, Gordon offered us tea but suggested that first we ought to get out and collect some Deschampsia (D. caespitosa, the tufted hair-grass), as it was at the end of its ripening window (of less than 2 weeks or so). With his characteristic enthusiasm and eneregy we headed to Pevensey Marsh with baskets and seed beaters to have a short session at paddling up some spikelets from the extensive stand that grows in an under-grazed area of the marsh. (It has small red grains, not dissimilar from the Ethiopian crop tef in terms of size).

From Gordon Hillman 2 Aug 2009

There was more time spent sitting and eating some fruit (foraged by Andy & Ehud from a supermarket) than actually collecting, with conversation taking up issues of harvesting windows for wild grasses, acorn gathering, processing and tree ownership, seaweed collection and Australian Auracaria pinecones. Having caught up we headed back to Gordon's kitchen to dehusk and grind some Deschampsia and Festuca he had gathered earler in the week and dried. And some simple wild grass biscuits were griddle cooked to accompany our cup of tea.

It is inspiring to see Gordon still add it, regularly out in field and forest, gathering, experimenting with processing and eating. And, he is still working on a book that gathers all of this knowledge and experience on wild food plants together.

The feitschrift contents have been presented previously on this blog. The book can be ordered from Oxbow Books. A full tally of Gordon's published works (so far) can be found here.

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.