Chris Stevens
University College London, Institute of Archaeology, Department Member
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Domestication is the process by which plants or animals evolved to fit a human-managed environment, and it is marked by innovations in plant morphology and anatomy that are in turn correlated with new human behaviours and technologies for... more
Domestication is the process by which plants or animals evolved to fit a human-managed environment, and it is marked by innovations in plant morphology and anatomy that are in turn correlated with new human behaviours and technologies for harvesting, storage and field preparation. Archaeobotanical evidence has revealed that domestication was a protracted process taking thousands of plant generations. Within this protracted process there were changes in the selection pressures for domestication traits as well as variation across a geographic mosaic of wild and cultivated populations. Quantitative data allow us to estimate the changing selection coefficients for the evolution of non-shattering (domestic-type seed dispersal) in Asian rice (<i>Oryza sativa</i> L.), barley (<i>Hordeum vulgare</i> L.), emmer wheat (<i>Triticum dicoccon</i> (Shrank) Schübl.) and einkorn wheat (<i>Triticum monococcum</i> L.). These data indicate that selection...
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As genetic and archaeological evidence has developed over the past few years, it has become apparent that our most basic assumptions about how crops became incorporated into human culture may be in need of fundamental revision.... more
As genetic and archaeological evidence has developed over the past few years, it has become apparent that our most basic assumptions about how crops became incorporated into human culture may be in need of fundamental revision. Conventionally, crop origins have been understood through a local founding model in which one or multiple centers of small localized populations are formed through cultivation leading to domesticated forms as plants adapt to local human environments either over short, or more recently, longer time frames. However, the genetic expectations of such models are not being met by archaeogenomic and archaeological data. A key concept to the local
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Sorghum bicolor, one of the world’s five most important crops, originated in Africa. While this has long been clear, accumulating data from both archaeobotany and genetics, provides the basis for a new overview on the domestication... more
Sorghum bicolor, one of the world’s five most important crops, originated in Africa. While this has long been clear, accumulating data from both archaeobotany and genetics, provides the basis for a new overview on the domestication process, racial evolution, and geographical dispersal of sorghum. Archaeobotanical finds from 113 sites in Africa and Eurasia are reviewed and mapped. Of these only 16 provide identifications of probable morphological races. Domestication is evidently taking place more than 3000 years BC in the eastern Sudan near the Atbara and Gash rivers. Early domesticated race bicolor then spread to South Asia around 2000 BC and to the Niger Basin in West Africa after 1000 BC. The framework of five cultivated races remains useful, with the original domesticated race bicolor being characterized by tight-fitting hulls requiring dehusking and the other races representing subsequent parallel evolution for free-threshing and larger-grained cultivars. This took place at least three times, including race ‘caudatum’ focused initially on the Sahelian region race ‘durra’ that evolved probably in India, and race ‘guinea’ that evolved in forested West Africa. Early race guinea in turn produced an even more forest adapted ‘mageritiferum’ type that appears to be ancestral to southern African guinea and ‘kafir’ sorghums, implying a dispersal across the central African rainforests. In contrast other eastern African caudatums and ‘bicolor’ types presumably followed a savannah dispersal. In addition to the early dispersal of race bicolor from Africa to India, which was ancestral to East Asian sorghums, a later dispersal of guinea types is inferred to have taken place from southeastern Africa across the Indian Ocean.
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Millets and rice were important for the demographic history of China. This review draws on current archaeobotanical evidence for rice and millets across China, Korea, eastern Russia, Taiwan, Mainland southeast Asia, and Japan, taking a... more
Millets and rice were important for the demographic history of China. This review draws on current archaeobotanical evidence for rice and millets across China, Korea, eastern Russia, Taiwan, Mainland southeast Asia, and Japan, taking a critical approach to dating evidence, evidence for cultivation, and morphological domestication. There is no evidence to suggest that millets and rice were domesticated simultaneously within a single region. Instead, 5 regions of north China are candidates for independent early cultivation of millets that led to domestication, and 3 regions of the Yangtze basin are candidates for separate rice domestication trajectories. The integration of rice and millet into a single agricultural system took place ca. 4000 BC, and after this the spread of agricultural systems and population growth are in evidence. The most striking evidence for agricultural dispersal and population growth took place between 3000 and 2500 BC, which has implications for major language...
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To what degree is cultural multi-level selection responsible for the rise of environmentally transformative human behaviors? And vice versa? From the clearing of vegetation using fire to the emergence of agriculture and beyond, human... more
To what degree is cultural multi-level selection responsible for the rise of environmentally transformative human behaviors? And vice versa? From the clearing of vegetation using fire to the emergence of agriculture and beyond, human societies have increasingly sustained themselves through practices that enhance environmental productivity through ecosystem engineering. At the same time, human societies have increased in scale and complexity from mobile bands of hunter-gatherers to telecoupled world systems. We propose that these long-term changes are coupled through positive feedbacks among social and environmental changes, coevolved primarily through selection acting at the group level and above, and that this can be tested by combining archeological evidence with mechanistic experiments using an agent-based virtual laboratory (ABVL) approach. A more robust understanding of whether and how cultural multi-level selection couples human social change with environmental transformation ...
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We consider the long-term relationship between human demography, food production, and Holocene climate via an archaeological radiocarbon date series of unprecedented sampling density and detail. There is striking consistency in the... more
We consider the long-term relationship between human demography, food production, and Holocene climate via an archaeological radiocarbon date series of unprecedented sampling density and detail. There is striking consistency in the inferred human population dynamics across different regions of Britain and Ireland during the middle and later Holocene. Major cross-regional population downturns in population coincide with episodes of more abrupt change in North Atlantic climate and witness societal responses in food procurement as visible in directly dated plants and animals, often with moves toward hardier cereals, increased pastoralism, and/or gathered resources. For the Neolithic, this evidence questions existing models of wholly endogenous demographic boom-bust. For the wider Holocene, it demonstrates that climate-related disruptions have been quasi-periodic drivers of societal and subsistence change.
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Domestication is the process by which plants or animals evolved to fit a human-managed environment, and it is marked by innovations in plant morphology and anatomy that are in turn correlated with new human behaviours and technologies for... more
Domestication is the process by which plants or animals evolved to fit a human-managed environment, and it is marked by innovations in plant morphology and anatomy that are in turn correlated with new human behaviours and technologies for harvesting, storage and field preparation. Archaeobotanical evidence has revealed that domestication was a protracted process taking thousands of plant generations. Within this protracted process there were changes in the selection pressures for domestication traits as well as variation across a geographic mosaic of wild and cultivated populations. Quantitative data allow us to estimate the changing selection coefficients for the evolution of non-shattering (domestic-type seed dispersal) in Asian rice (Oryza sativa L.), barley (Hordeum vulgare L.), emmer wheat (Triticum dicoccon (Shrank) Schübl.) and einkorn wheat (Triticum monococcum L.). These data indicate that selection coefficients tended to be low, but also that there were inflection points a...
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Recent increases in archaeobotanical evidence offer insights into the processes of plant domestication and agricultural origins, which evolved in parallel in several world regions. Many different crop species underwent convergent... more
Recent increases in archaeobotanical evidence offer insights into the processes of plant domestication and agricultural origins, which evolved in parallel in several world regions. Many different crop species underwent convergent evolution and acquired domestication syndrome traits. For a growing number of seed crop species, these traits can be quantified by proxy from archaeological evidence, providing measures of the rates of change during domestication. Among domestication traits, nonshattering cereal ears evolved more quickly in general than seed size. Nevertheless, most domestication traits show similarly slow rates of phenotypic change over several centuries to millennia, and these rates were similar across different regions of origin. Crops reproduced vegetatively, including tubers and many fruit trees, are less easily documented in terms of morphological domestication, but multiple lines of evidence outline some patterns in the development of vegecultural systems across the ...
Research Interests: Ancient History, Botany, Geography, Archaeology, Transformative Learning, and 14 moreArchaeobotany, Biology, Agriculture, Neolithic Archaeology, Medicine, Multidisciplinary, Ancient Agriculture & Farming (Archaeology), Domestication, PNAS, Biological evolution, Crop, Time Factors, Vegeculture, and archaeological evidence
The period from the late third millennium BC to the start of the first millennium AD witnesses the first steps towards food globalization in which a significant number of important crops and animals, independently domesticated within... more
The period from the late third millennium BC to the start of the first millennium AD witnesses the first steps towards food globalization in which a significant number of important crops and animals, independently domesticated within China, India, Africa and West Asia, traversed Central Asia greatly increasing Eurasian agricultural diversity. This paper utilizes an archaeobotanical database (AsCAD), to explore evidence for these crop translocations along southern and northern routes of interaction between east and west. To begin, crop translocations from the Near East across India and Central Asia are examined for wheat (Triticum aestivum) and barley (Hordeum vulgare) from the eighth to the second millennia BC when they reach China. The case of pulses and flax (Linum usitatissimum) that only complete this journey in Han times (206 BC-AD 220), often never fully adopted, is also addressed. The discussion then turns to the Chinese millets, Panicum miliaceum and Setaria italica, peaches...
Research Interests: History, Geography, Asian Studies, Archaeology, Prehistoric Archaeology, and 15 moreGeology, Archaeobotany, Chinese Studies, Agriculture, China, South Asian Archaeology, Medicine, Archaeology of Central Asia, Prehistory, Crop Science, Phytolith, Panicum miliaceum, Millet, Crop, and Central Asian History and Anthropology
This paper outlines a model for the domestication of Panicum miliaceum (broomcorn millet) in Northern China. Data from 43 archaeological sites indicate a continuous increase in average grain size between 6000 and 3300 bc. After this date... more
This paper outlines a model for the domestication of Panicum miliaceum (broomcorn millet) in Northern China. Data from 43 archaeological sites indicate a continuous increase in average grain size between 6000 and 3300 bc. After this date there is a divergence, with grain size continuing to increase in some populations, while others show no further size increase. The initial increase in grain size is attributed to selection during domestication, while later divergence after 3300 bc is interpreted as resulting from post-domestication selection. Measurements of grains from two archaeological populations of P. ruderale, showed grains were longer in length by 3300 bc than the earliest grains of P. miliaceum. This suggests this sub-species includes many feral, weedy and/or introgressed forms of P. miliaceum and therefore is probably not entirely representative of the true wild ancestor. It is argued that changes from shattering to non-shattering are contemporary with increasing grain size...
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This paper rewrites the early history of Britain, showing that while the cultivation of cereals arrived there in about 4000 cal BC, it did not last. Between 3300 and 1500 BC Britons became largely pastoral, reverting only with a major... more
This paper rewrites the early history of Britain, showing that while the cultivation of cereals arrived there in about 4000 cal BC, it did not last. Between 3300 and 1500 BC Britons became largely pastoral, reverting only with a major upsurge of agricultural activity in the Middle Bronze Age. This loss of interest in arable farming was accompanied by a decline in population, seen by the authors as having a climatic impetus. But they also point to this period as the time of construction of the great megalithic monuments, including Stonehenge. We are left wondering whether pastoralism was all that bad, and whether it was one intrusion after another that set the agenda on the island.
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Barnett, C. 2011. The Tilbury Alluvial Sequence and a Submerged Forest of Neolithic Age at 118 Victoria Dock Road, Canning Town, East London. LAMAS 62, 1-15 Archaeological evaluation of a small redevelopment site in Canning Town... more
Barnett, C. 2011. The Tilbury Alluvial Sequence and a Submerged Forest of Neolithic Age at 118 Victoria Dock Road, Canning Town, East London. LAMAS 62, 1-15
Archaeological evaluation of a small redevelopment
site in Canning Town revealed a deep, well-stratified
Holocene alluvial sequence (the Tilbury Formation)
to 5.8m depth (-4.75m OD) over Devensian fluvial
sands and gravels. A thin peat (the lower peat) at
c.5.5—5.75m depth (-4.45 to -4.7m OD) contained tree
trunks, some with roots attached. The layer was sampled
and assessed for plant macrofossils, wood and molluscs
and was radiocarbon dated to the early Neolithic
(3940—3700 cal bc), probably relating to the Tilbury
III regression. Floodplain alder carr and surrounding
mixed deciduous woodland were inundated in the
Early Neolithic by Thames flood waters during marine
transgression and have been preserved in situ as a
submerged forest. Human activity in the local forest is
indicated by the presence of wood charcoal and scorched
snails but no archaeological features or artefacts were
found.
The thick overlying sediment sequence contained
two further main bodies of peat dating to the end of
the Early Neolithic (3350—3030 cal bc) and Middle
Bronze Age (1400—1130 cal bc), correlating broadly
with other Tilbury sequences in London and with
a shallower peat sequence at Silvertown, where a
Neolithic trackway was identified. The pollen indicates
the continuation of dense and relatively undisturbed
forest for the Neolithic to Middle Bronze Age wetland
edge landscape. Although long-term settlement of the
area would not have been feasible due to the fluctuation
and instability of these wetlands, it is likely that the
area offered opportunities for economic activities such
as fishing and fowling.
Excellent preservation by waterlogging in this deep
sequence has been demonstrated and archaeological
evidence in the form of organic remains, eg trackways
and fishtraps, may be discovered in the area in the
future.
Archaeological evaluation of a small redevelopment
site in Canning Town revealed a deep, well-stratified
Holocene alluvial sequence (the Tilbury Formation)
to 5.8m depth (-4.75m OD) over Devensian fluvial
sands and gravels. A thin peat (the lower peat) at
c.5.5—5.75m depth (-4.45 to -4.7m OD) contained tree
trunks, some with roots attached. The layer was sampled
and assessed for plant macrofossils, wood and molluscs
and was radiocarbon dated to the early Neolithic
(3940—3700 cal bc), probably relating to the Tilbury
III regression. Floodplain alder carr and surrounding
mixed deciduous woodland were inundated in the
Early Neolithic by Thames flood waters during marine
transgression and have been preserved in situ as a
submerged forest. Human activity in the local forest is
indicated by the presence of wood charcoal and scorched
snails but no archaeological features or artefacts were
found.
The thick overlying sediment sequence contained
two further main bodies of peat dating to the end of
the Early Neolithic (3350—3030 cal bc) and Middle
Bronze Age (1400—1130 cal bc), correlating broadly
with other Tilbury sequences in London and with
a shallower peat sequence at Silvertown, where a
Neolithic trackway was identified. The pollen indicates
the continuation of dense and relatively undisturbed
forest for the Neolithic to Middle Bronze Age wetland
edge landscape. Although long-term settlement of the
area would not have been feasible due to the fluctuation
and instability of these wetlands, it is likely that the
area offered opportunities for economic activities such
as fishing and fowling.
Excellent preservation by waterlogging in this deep
sequence has been demonstrated and archaeological
evidence in the form of organic remains, eg trackways
and fishtraps, may be discovered in the area in the
future.
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Abstract The origins of agriculture involved pathways of domestication in which human behaviours and plant genetic adaptations were entangled. These changes resulted in consequences that were unintended at the start of the process. This... more
Abstract The origins of agriculture involved pathways of domestication in which human behaviours and plant genetic adaptations were entangled. These changes resulted in consequences that were unintended at the start of the process. This paper highlights some of the key innovations in human behaviours, such as soil preparation, harvesting and threshing, and how these were coupled with genetic &amp;amp;amp;amp;amp;amp;amp;amp;#x27;innovations&amp;amp;amp;amp;amp;amp;amp;amp;#x27; within plant populations. We identify a number of &amp;amp;amp;amp;amp;amp;amp;amp;#x27;traps&amp;amp;amp;amp;amp;amp;amp;amp;#x27; for early cultivators, including the needs for extra labour ...