Contrasting patterns in crop domestication and domestication rates: recent archaeobotanical insights from the Old World

BACKGROUND: Archaeobotany, the study of plant remains from sites of ancient human activity, provides data for studying the initial evolution of domesticated plants. An important background to this is defining the domestication syndrome, those traits by which domesticated plants differ from wild relatives. These traits include features that have been selected under the conditions of cultivation. From archaeological remains the easiest traits to study are seed size and in cereal crops the loss of natural seed dispersal. SCOPE: The rate at which these features evolved and the ordering in which they evolved can now be documented for a few crops of Asia and Africa. This paper explores this in einkorn wheat (Triticum monococcum) and barley (Hordeum vulgare) from the Near East, rice (Oryza sativa) from China, mung (Vigna radiata) and urd (Vigna mungo) beans from India, and pearl millet (Pennisetum glaucum) from west Africa. Brief reference is made to similar data on lentils (Lens culinaris), peas (Pisum sativum), soybean (Glycine max) and adzuki bean (Vigna angularis). Available quantitative data from archaeological finds are compiled to explore changes with domestication. The disjunction in cereals between seed size increase and dispersal is explored, and rates at which these features evolved are estimated from archaeobotanical data. Contrasts between crops, especially between cereals and pulses, are examined. CONCLUSIONS: These data suggest that in domesticated grasses, changes in grain size and shape evolved prior to non-shattering ears or panicles. Initial grain size increases may have evolved during the first centuries of cultivation, within perhaps 500-1000 years. Non-shattering infructescences were much slower, becoming fixed about 1000-2000 years later. This suggests a need to reconsider the role of sickle harvesting in domestication. Pulses, by contrast, do not show evidence for seed size increase in relation to the earliest cultivation, and seed size increase may be delayed by 2000-4000 years. This implies that conditions that were sufficient to select for larger seed size in Poaceae were not sufficient in Fabaceae. It is proposed that animal-drawn ploughs (or ards) provided the selection pressure for larger seeds in legumes. This implies different thresholds of selective pressure, for example in relation to differing seed ontogenetics and underlying genetic architecture in these families. Pearl millet (Pennisetum glaucum) may show some similarities to the pulses in terms of a lag-time before truly larger-grained forms evolved.     

Alien species reflecting history: medieval castles in Germany

Ninety‐seven alien plant species were found in habitats provided by rocks and walls around 56 castles in Germany. Compared to Central European agriophytes (i.e. alien species naturalised in natural vegetation), the flora adjacent to castles had more species introduced before 1500. More alien species introduced earlier were found at castles built earlier compared to castles built later. Fifty percent of the species introduced before and during the Middle Ages were usable plants at that time, compared to 20% of usable plants among the native species in the same habitats. Species introduced earlier were mainly used for medication and nutrition, whereas later introductions were used for ornamental purposes. Compared to the total alien flora of Germany, there were more useable species at the castles, nearly the same percentage of ornamentals and fewer plants without use. These results imply that the species composition of alien species growing in the vicinity of medieval castles today may be traced back to the historical reasons for their introduction to these places.     

An experimental approach to Neolithic shifting cultivation

Archaeobotanical data from Late Neolithic lake-shore dwellings (4300-3500 cal B.C.) in the northern Pre-alpine lowlands are interpreted in different ways. The presence of permanent arable fields as well as arable fields with short fallow phases and shifting cultivation with slash-and-burn has been discussed. To test these hypotheses experimentally we have been conducting tests in a forest northeast of Stuttgart since 1994. The slightly south-exposed experimental area of approximately 4.5 ha on a loess soil is covered by mixed deciduous forest, is available for at least 20 years and has been divided into 34 plots of 30 × 30 m. Up to 2001, five plots were used for experiments. The normal procedure is clearing, burning the dry small timber (less than 10 cm in diameter) and then growing winter cereals (bread wheat) for one season. The yields were between 2000 and 4000 kg grains per ha. The harvest was more or less free from weeds. First attempts with summer crops gave much lower yields of about 1100 kg grains per ha. Continuous cereal growing on the same place in the following years resulted in minimal to zero yields, mainly due to vigorous weed growth. These weeds are not crop weeds, but forest perennials of clearings and forest fringes. Ploughing to remove the weeds is not possible, because of the presence of roots and tree-stumps, most of them still living. Weed regulation by hoeing, burning or cattle grazing remains to be tested. Protection of the crop from game and birds is by fences and nets, but protection from mice seems difficult. In the spectra from the pollen traps, clearing and burning are strongly indicated, but cereal growing only slightly. Received July 31, 2001 / Accepted April 9, 2002     

Vitis vinifera in the Iberian Peninsula: A review

The origin of the Eurasian grapevine, Vitis vinifera L. and the different steps in the development of viticulture from the wild grapevine to the modern varietal situation in the Iberian Peninsula are reviewed here. The ancestors of Vitis vinifera subs. sylvestris, the only representative of the Vitis genus in natural Eurasian and North African ecosystems, appeared in the late Miocene. In the Iberian Peninsula, human action has significantly reduced the habitat of this species, whose oldest palaeobotanical remains go back to the late Pleistocene. The introduction of viticulture in Iberia is connected with the relationships between the indigenous population and the trading colonies founded by Phoenicians and Greeks. In this way, there is evidence of wine production and consumption, even as a ritual and prestige item, going back to the third millennium BP. Chloroplast genome studies carried out in wild and cultivated plants indicate that a secondary domestication process occurred in the Iberian Peninsula and this is reflected in the “A” chlorotype, which contrasts with the predominance of the “B” and “C” chlorotypes in wild and domesticated vines in the Transcaucasian region, where domesticated grapes at sites of the Shulaveri Culture (Georgia) are evidence of early viticulture around 8000 BP.     

Urartian plant cultivation at Yoncatepe (Van), eastern Turkey

Plant remains were recovered from an Urartian settlement, Yoncatepe, situated in the Van province of eastern Turkey and dating to the Iron Age period (first millennium B.C.E.). Large quantities of hulled barley (Hordeum vulgare L.) and of bread/macaroni wheat (free-threshing wheat) Triticum aestivum L./T. durum Desf.), both mixed with small quantities of domesticated emmer wheat (T. dicoccum Schübl.), were found in the storerooms of the Yoncatepe palace, indicating the storage of agricultural surplus. Rye (Secale cereale L.) grains occur very occasionally, while pulses include lentil (Lens culinaris Medik.), chickpea (Cicer arietinum L.), and bitter vetch (Vicia ervilia [L.] Willd.). Grape seeds unearthed in a tomb at Yoncatepe provide physical evidence supporting written records of vineyards. Numerous seeds of gold of pleasure (Camelina sativa [L.] Crantz), found in a storage vessel, provide evidence of the cultivation of this plant. It is likely, that the Urartians used the seeds for oil extraction.     

Early agriculture and crop transmission among Bronze Age mobile pastoralists of Central Eurasia

Archaeological research in Central Eurasia is exposing unprecedented scales of trans-regional interaction and technology transfer between East Asia and southwest Asia deep into the prehistoric past. This article presents a new archaeobotanical analysis from pastoralist campsites in the mountain and desert regions of Central Eurasia that documents the oldest known evidence for domesticated grains and farming among seasonally mobile herders. Carbonized grains from the sites of Tasbas and Begash illustrate the first transmission of southwest Asian and East Asian domesticated grains into the mountains of Inner Asia in the early third millennium BC. By the middle second millennium BC, seasonal camps in the mountains and deserts illustrate that Eurasian herders incorporated the cultivation of millet, wheat, barley and legumes into their subsistence strategy. These findings push back the chronology for domesticated plant use among Central Eurasian pastoralists by approximately 2000 years. Given the geography, chronology and seed morphology of these data, we argue that mobile pastoralists were key agents in the spread of crop repertoires and the transformation of agricultural economies across Asia from the third to the second millennium BC.