C14 dates at Wadi Kubbaniya, Egypt

New radiocarbon dates and Late Palaeolithic diet at Wadi Kubbaniya, Egypt

I was overhauling  my old entry on Wadi Kubbaniya, and found this. Its about 20 years old now. The most important observation from it was that the C14 dates found on the domesticated barley at the site were very wrong. They were not 18,000 years old, but instead well within the neolithic era.  This lead to some older Wendorf papers mentioning agriculture as appearing first in this area, which he later corrected.

The use of grinders to make tubers more digestible would be a logical intermediate step on the way to eating wild grass seeds. If you think about it, grinding up a plump (if  inedible unprocessed) tuber that can be easily pulled up by hand makes more sense than designing a complex specialist tool to cut through grass stalks, and then inventing the quern. So it may be that access to the tubers as a food source was the cue to the expansion from upper Egypt, not grain, which may have followed considerably later, as late as nine thousand years is possible.

Vegetable remains are a rarity in Palaeolithic contexts. These new determinations on material from southern Egypt establish securely the date of an intensive grass-tuber and fish economy in the Nile Valley towards 20,000 years ago.

In 1978, during test excavations at a group of Late Palaeolithic sites in Wadi Kubbaniya, near Aswan, Egypt, several grains of barley and one grain of einkorn were found, seemingly firmly associated with a buried hearth (E-78-4) (Wendorf et al. 1979; 1980). Because of the potential significance of this discovery, a major effort was made in 1981-4 to recover more remains of food plants, particularly cereals. Large-scale excavations were conducted at three localities (E-78-3, E-78-4 and E-81-1), and 24 others were partially excavated or tested. Our discussion here will be limited to sites in one geomorphic settings: those in the massive field of dune sand and interfingering lenses of Nile silt. The stone artefacts at the sites are characterized by an abundance of Ouchtate bladelets, which sometimes make up over 80% of the retouched tools, occasional, well-made burins (often on Levallois flakes), scaled pieces, notches, denticulates and truncations.

Flotation could not be used for plant recovery because most of the remains were extremely fragile and disintegrated on contact with water. Instead, several hundred cubic metres of dry sediment were processed through specially constructed sets of graded screens. This yielded a large quantity of plant remains, including barley grains from near the surface of site E-78-3 and date-stones from E-78-3 and E-81-1. Some of the barley grains were blackish in colour, but neither they nor the date-stones were actually charred. Numerous grinding-stones, presumed to have been used for processing the cereals, were found in the sites, often deeply buried, and reinforced the supposed association of the cereals with the Late Palaeolithic occupations. Radiocarbon dates on associated wood charcoal placed the occupations between 18,500 and 17,000 b.p. These finds led some of us to suggest an early origin of food production, with subsequent implications for the initial development of complex societies.

While the Kubbaniya excavations were still under way, it became possible to date very small samples, even individual cereal grains, by the then-new technology of the tandem accelerator mass spectrometer (AMS), and the Kubbaniya cereals and date-stones were among the first materials dated by this technology. The cereal grains were dated at the University of Arizona, Tucson, and the date-stones at the Oxford University facility; all were shown to be relatively modern contaminants.The idea that cereals and dates had been important components of the Late Palaeolithic economy of Wadi Kubbaniya was therefore abandoned (Wendorf et al. 1984; Gowlett 1987).

Although we are still unable to agree on how apparently undisturbed archaeological horizons were contaminated by relatively modern plant materials, this experience demonstrates that we must be extremely cautious in evaluating the association of isolated plant fragments with archaeological contexts. At the very least, all such materials found outside their expected areal or temporal ranges should be subjected to direct (AMS) dating, and many of those within their expected ranges should also be dated (Harris 1986; 1987; Legge 1986).

The charred plant remains recovered at the Kubbaniyan sites consisted mostly of wood charcoal, all of which has been identified as tamarisk (Tomczynska, in press). There was also a significant collection of food plant preserved by charring, among which most of the identified specimens are purple nut-grass tubers (Cyperus rotundus). Other identified remains include tubers of club-rush (Scirpus sp. of the S. maritimus or S. tuberosus type), a fern, seeds of chamomile, asparagus, club-rush, an umbell, the receptacle from a flower-bud of a water-lily and fruit fragments of dom palm (Hyphaene thebaica) and Tribulus; identified seeds from human coprolites include club-rush and chamomile (Hillman et al. in press; Hillman in press). These plants still occur today along the Nile and grow either on the terraces and banks, or in marshy areas adjacent to the river.

After the experience with the cereals and data-stones, it seemed prudent to submit several samples of the most abundant class of charred plant-food remains for AMS dating. Twelve specimens were selected, including 11 tubers of purple nut-grass and one tuber of a club-rush. Three specimens were selected from each of two sites and six from the third, all of them indisputably charred. The results are shown in TABLE 1.

Prior to the accelerator measurement, the samples were combusted to CO2, which was then converted by a catalytic process to graphite powder. The graphite powder was packed under pressure into an aluminum target holder and mounted in the ion source of the accelerator. The ratios of 14C/13C in the target samples and in standard samples made from, NBS oxalic acid were made in the manner described by Donahue et al. (in press). the ages given in TABLE 1 are radiocarbon ages calculated from 14C half-life of 5568 years, and the uncertainties are standard deviations of the average of several measurements of each quantity. The measurements were not corrected for variation in 13C/12C ratios. Such corrections would not change the results by more than 25 years.

The results thus confirm that the charred Cyperus tubers were contemporaneous with the Late Palaeolithic occupations. They are in general agreement with the radiocarbon dates given in TABLE 2, which were obtained by traditional methods on wood charcoal from the same layers of the same sites (Haas in press).

However, the AMS and conventional dates do not correspond entirely: statistical analysis shows that AMS dates are definitely younger at site E-81-1, tend to be rather younger at Site E-78-3, and tend to be rather older at Site E-78-4 (Hietala in press). Further research will be needed to resolve this discrepancy.

The excavation techniques used at Kubbaniya resulted not only in the recovery of plant-remains, but also of a much more complete faunal collection than had previously been known from the Nile Valley. This is particularly true of the fish fauna, which includes the fragile remains of young animals and smaller species. Together, the faunal and floral collections recovered from the Kubbaniyan sites provide our first glimpse of what must have been a very complex and seasonally diverse diet during the Late Palaeolithic in the Nile Valley (Gautier & Van Neer in press; Hillman et al. in press; Hillman in press).

When mature, the wet-land tubers are rich in carbohydrates, but they must also contain toxins and an excess of fibre and must be processed before they can be consumed in quantity. The processing includes roasting, crushing, grinding and perhaps leaching to eliminate the toxins and to make the fibre more digestible. We suggest that the grinding stones in the sites were used primarily for this purpose, and for the grinding of other fibrous foods, such as reed rhizomes and Hyphaene fruits (Hillman et al. in press). Such use is also indicated by the chemical analysis of traces of organic compounds on one of the grinding-stones, showing high values for cellulosics (which could indicate starch, as well as cellulose sensu stricto) and low values for proteins (Jones in press).

The collections of fish bones from the Kubbaniyan sites in the dune field consist primarily of adult catfish (Clarias), with an occasional Tilapia and eel (Gautier & Van Neer in press). this is interpreted as reflecting a massive harvest of catfish during the spawn, which in the Nile Valley begins with the onset of the seasonal flood (in July) and ends just before the water begins to recede (in early September). The excavations also yielded numbers of bird bones, many of which are of sucks and geese which today winter in Egypt, plus rather less frequent bones of large mammals (essentially wild cattle, hartebeest and gazelle). there were occasional shells of Unio abyssinicus, an edible freshwater mussel.

The floral and faunal remains from the dune sites also provide our best clues to the seasonal use of these localities. The yearly round in the Nile Valley begins with the seasonal flood, which rises gradually in early July but then expands rapidly to reach its peak, 7m or more above low water, in mid-August and early September. There is an almost equally rapid decline, with the season of lowest waters from February through June. At peak flood, the water spreads far beyond its normal limits and covers the broad floodplain. In the Late Palaeolithic, the channels of the main river were several metres higher than today and the seasonal rise was at least as great. Thus, during the season of the maximum flood, the floodplain extended several kilometres up Wadi Kubbaniya, over and beyond the massive dunefield in which the sites occur.

It was probably during the period of rising water, from perhaps mid-July until just before the peak of the flood in mid-August, the the intensive harvest of spawning catfish occurred (Gautier & Van Neer in press). The quantities of fish taken during the spawn harvest were so large (one site yielded 130,280 fish bones) that they may have exceeded immediate needs and some of the fish may have been dried or smoked for later consumption.

When the floodwaters covered the dune sites, the people either shifted to the sandstone escarpments on either side of the wadi or, more likely, simply moved up the wadi ahead of the flood to continue the fish-harvest at the edge of the water. Sites that might have been occupied during the highest-water phase are not known; they have presumably been destroyed by deflation. There may also have been some large mammal hunting at this time. The rising water would have forced the animals from the lowland areas to the edge of the floodplain where there was less cover and beyond which there was neither food nor shelter.

As the floodwaters began to recede, fishing probably continued in the swales and cut-off ponds, although we have no direct evidence of this. Such evidence would be extremely difficult to detect among the numerous bones resulting from the spawn-harvest, although distinctive fish spectra, indicating post-flood fishing in cut-off pools, were recovered at some earlier Late Palaeolithic sites in the area.

Plants were also important components of the diet after the seasonal flood. Among the first may have been seeds of annuals, including chamomile, which are available in October soon after the flood recedes. The gathering of nut-grass and club-rush tubers could have begun at about the same time, at which point they would have required only rubbing and roasting to be edible (Hillman et al. in press). However, they reach their maximum food-value only at maturity, in December and January, when they also require complex processing, including grinding or pounding. The grinding-stones and carbonized tubers in the dune sites suggest occupation during the winter months. Purple nut-grass probably grew as a dense carpet over much of the wadi, including the dune areas, and a surplus beyond immediate needs could have been gathered at this time and stored for later consumption; once dried, the tubers retain their food value for several months. It was probably also during the winter that the ducks and geese were taken.

Use of the dunes sites still later in the year is indicated by the presence of dom palm fruits, which mature in February and March, and by the occasional shells of Unio abyssinicus; the Unio probably could be gathered only in the period between February and the end of June. However, there is no evidence that these sites were much used in the driest part of the year (from March until July), and, indeed, it seems likely that most settlements at that time were inside the valley, close to the deeper channels. Such sites are unknown at Kubbaniya and will be rarely found elsewhere, since most of them were destroyed by the down-cutting by the river during the Holocene.

Large mammals were probably taken throughout the year, but they were not so important as fish as sources of protein and fats. Despite the larger size and greater density of mammal bones, they represent only about 1% of all bone in the dune sites. It is possible that these sites were not used during the major hunting periods, but the fish and floral remains indicate some use of them during most of the year.

It is important to note that we are not suggesting semi-permanent or permanent occupations, but rather a settlement system which involved the re-use of key areas to exploit a variety of seasonal resources. Hillman and others (in press) have observed that the plant-food resources which would have been locally available could have supported occupation in one location for most of the year, even without food-storage, but there is no direct evidence for the use of all these potential resources. Instead, the evidence suggests a new economic system in the Nile Valley, based upon the intensive exploitation of a few seasonally available foods which lend themselves to processing and storage for later consumption. Such intensive exploitation is evident in the summer when large quantities of spawning catfish were taken, and in the autumn, winter and spring when wet-land tubers were gathered and processed. Together, these two foods could have provided all the basic components of a balanced diet: the catfish are rich in protein and fat and the wet-land tubers and dom palm fruits contribute the carbohydrates and dietary fibre. Other sources of food were certainly known and used, but their contribution to the diet may have been not essential and less important.