The Making of the Botanical Battleground 'The development of plant communities on agricultural la... more The Making of the Botanical Battleground 'The development of plant communities on agricultural land can thus be seen in part as a battle between weed communities and human communities, in which stakes for both parties are high'
Domestication is the process by which plants or animals evolved to fit a human-managed environmen... 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...
As genetic and archaeological evidence has developed over the past few years, it has become appar... 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
Sorghum bicolor, one of the world’s five most important crops, originated in Africa. While this h... 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.
Millets and rice were important for the demographic history of China. This review draws on curren... 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...
New excavations at the Jebel Moya cemetery in Sudan reveal extensive evidence for Meroitic-era oc... more New excavations at the Jebel Moya cemetery in Sudan reveal extensive evidence for Meroitic-era occupation, providing valuable data on contemporaneous diet, migration, exchange and population composition in sub-Saharan Africa.
To what degree is cultural multi-level selection responsible for the rise of environmentally tran... 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 ...
Proceedings of the National Academy of Sciences of the United States of America, Dec 20, 2017
We consider the long-term relationship between human demography, food production, and Holocene cl... 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.
Philosophical transactions of the Royal Society of London. Series B, Biological sciences, Jan 5, 2017
Domestication is the process by which plants or animals evolved to fit a human-managed environmen... 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...
Our suggestion that agriculture was temporarily abandoned for several centuries throughout much o... more Our suggestion that agriculture was temporarily abandoned for several centuries throughout much of mainland Britain after 3600 BC has provoked criticism, notably the claim by Bishop (2015) that we have missed continuity in Scotland. We demonstrate that firm evidence for widespread agriculture within the later Neolithic is still unproven. We trace the disappearance of cereals and the associated population collapse to a probable climatic shift that impacted the abundance of rainfall and lowered temperatures, thus affecting the reliability of cereals. Divergent strategies and patterns are identified on the Scottish Islands versus the mainland, which has more in common with England, Wales and Ireland. We argue that climate shocks disrupt existing subsistence patterns, to which varied responses are represented by divergent island and mainland patterns, both in the Late Neolithic and during the Early and Middle Bronze Age. Favourable climates encouraged population growth and subsistence innovation, such as at the start of the Neolithic and in the Beaker period.
Proceedings of the National Academy of Sciences of the United States of America, Jan 29, 2014
Recent increases in archaeobotanical evidence offer insights into the processes of plant domestic... 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 ...
The period from the late third millennium BC to the start of the first millennium AD witnesses th... 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...
This paper outlines a model for the domestication of Panicum miliaceum (broomcorn millet) in Nort... 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...
This paper presents new excavation data and new radiometric dates for Jebel Moya, south-central S... more This paper presents new excavation data and new radiometric dates for Jebel Moya, south-central Sudan. These data suggest revisions to previous chronological understandings of the site. New excavations, initiated in 2017, show a longer, more continuous occupation of the site than has been previously recognised. Archaeozoological and archaeobotanical analyses provide evidence for domesticated taxa. Archaeobotanical evidence is dominated by domesticated sorghum (Sorghum bicolor), radiocarbon dated to c. 2550-2210 BC. Faunal remains include cattle and goat/sheep. A late third-millennium BC date on the human skeleton excavated in the 2017 season also shows that mortuary activity began early in the site's history, contemporary with domesticated faunal and botanical remains. These initial results indicate the long-term association of the site with pastoralism and agriculture and with environmental change. Jebel Moya's continued potential to serve as a chronological and cultural reference point for future studies in south-central Sudan and the eastern Sahel is reinforced.
Interdisciplinaria Archaeologica - Natural Sciences in Archaeology
High Resolution X-Ray Computed Tomography (HRXCT) offers a powerful 3-dimensional, nondestructive... more High Resolution X-Ray Computed Tomography (HRXCT) offers a powerful 3-dimensional, nondestructive and non-invasive diagnostic tool for imaging the external and internal structures of a range of specimens of interest including archaeobotanical remains. HRXCT offers new possibilities in terms of the research questions which may be asked of fragile and valuable archaeological and specifically archaeobotanical material. This technology, although currently somewhat limited in terms of time and access to beamtimes at National Synchrotrons, requires simple, non-destructive preparation of samples and produces exciting results. Based upon two rounds of successful work, we believe that this new methodology has wider implications and utility for advancing the field of imaging, and investigating aspects of plant domestication such as internal anatomical changes.
We report archaeobotanical results from systematic flotation at what is presently the earliest Ne... more We report archaeobotanical results from systematic flotation at what is presently the earliest Neolithic site with hard evidence for crop cultivation in the Southwestern Chinese province of Yunnan, at the site of Baiyangcun. Direct AMS dates on rice and millet seeds, included together in a Bayesian model, suggests that sedentary agricultural occupation began ca. 2650 BCE, with cultivation of already domesticated rice (Oryza sativa), broomcorn millet (Panicum miliaceum), and foxtail millet (Setaria italica). Soybean (Glycine cf. max) was also present and presumably cultivated, although it still resembles its wild progenitor in terms of seed size. Additional possible cultivars include melon (Cucumis melo) and an unknown Vigna pulse, while wild gathered resources include fruits and nuts, including hawthorn (Crateagus) and aquatic foxnut (Euryale ferox). Weed flora suggests at least some rice was cultivated in wet (flooded or irrigated fields), while dryland weeds may derive from millet fields. This subsistence system persisted throughout the site's occupation, up to ca. 2050 BCE. These data provide secure evidence for the spread of Chinese Neolithic crops to Yunnan, and provide new evidence for reconstructing possible sources of cereal agriculture in mainland Southeast Asia.
The transition to urbanism has long focused on annual staple crops (cereals and legumes), perhaps... more The transition to urbanism has long focused on annual staple crops (cereals and legumes), perhaps at the expense of understanding other changes within agricultural practices that occurred between the end of the initial domestication period and urbanisation. This paper examines the domestication and role of fruit tree crops within urbanisation in both Western Asia and China, using a combination of evidence for morphological change and a database that documents both the earliest occurrence of tree fruit crops and their spread beyond their wild range. In Western Asia the domestication of perennial fruit crops likely occurs between 6500 bc and 3500 bc, although it accompanies a shift in location from that of the earliest domestications within the Fertile Crescent to Mesopotamia, where the earliest urban societies arose. For China, fruit-tree domestication dates between ca 4000 and 2500 bc, commencing after millet domestication and rice domestication in Northern and Southern China, respectively, but within the period that led up to the urban societies that characterised the Longshan period in the Yellow River basin and the Liangzhu Culture in the Lower Yangtze. These results place the domestication of major fruit trees between the end of the domestication of staple annual crops and the rise of urbanism. On this basis it is argued that arboriculture played a fundamental role within the re-organisation of existing land use, shifting the emphasis from short-term returns of cereal crops into longer term investment in the developing agricultural landscape in both Western and East Asia. In this respect perennial tree crops can be placed alongside craft specialisation, such as metallurgy and textiles, in the formation of urban centres and the shaping the organisational administration that accompanied the rise of urbanism.
The evolution of domesticated cereals was a complex interaction of shifting selection pressures a... more The evolution of domesticated cereals was a complex interaction of shifting selection pressures and repeated episodes of introgression. Genomes of archaeological crops have the potential to reveal these dynamics without being obscured by recent breeding or introgression. We report a temporal series of archaeogenomes of the crop sorghum (Sorghum bicolor) from a single locality in Egyptian Nubia. These data indicate no evidence for the effects of a domestication bottleneck, but instead suggest a steady decline in genetic diversity over time coupled with an accumulating mutation load. Dynamic selection pressures acted sequentially to shape architectural and nutritional domestication traits, and to facilitate adaptation to the local environment. Later introgression between sorghum races allowed exchange of adaptive traits and achieved mutual genomic rescue through an ameliorated mutation load. These results reveal a model of domestication in which genomic adaptation and deterioration was not focused on the initial stages of domestication but occurred throughout the history of cultivation.
The Making of the Botanical Battleground 'The development of plant communities on agricultural la... more The Making of the Botanical Battleground 'The development of plant communities on agricultural land can thus be seen in part as a battle between weed communities and human communities, in which stakes for both parties are high'
Domestication is the process by which plants or animals evolved to fit a human-managed environmen... 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...
As genetic and archaeological evidence has developed over the past few years, it has become appar... 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
Sorghum bicolor, one of the world’s five most important crops, originated in Africa. While this h... 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.
Millets and rice were important for the demographic history of China. This review draws on curren... 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...
New excavations at the Jebel Moya cemetery in Sudan reveal extensive evidence for Meroitic-era oc... more New excavations at the Jebel Moya cemetery in Sudan reveal extensive evidence for Meroitic-era occupation, providing valuable data on contemporaneous diet, migration, exchange and population composition in sub-Saharan Africa.
To what degree is cultural multi-level selection responsible for the rise of environmentally tran... 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 ...
Proceedings of the National Academy of Sciences of the United States of America, Dec 20, 2017
We consider the long-term relationship between human demography, food production, and Holocene cl... 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.
Philosophical transactions of the Royal Society of London. Series B, Biological sciences, Jan 5, 2017
Domestication is the process by which plants or animals evolved to fit a human-managed environmen... 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...
Our suggestion that agriculture was temporarily abandoned for several centuries throughout much o... more Our suggestion that agriculture was temporarily abandoned for several centuries throughout much of mainland Britain after 3600 BC has provoked criticism, notably the claim by Bishop (2015) that we have missed continuity in Scotland. We demonstrate that firm evidence for widespread agriculture within the later Neolithic is still unproven. We trace the disappearance of cereals and the associated population collapse to a probable climatic shift that impacted the abundance of rainfall and lowered temperatures, thus affecting the reliability of cereals. Divergent strategies and patterns are identified on the Scottish Islands versus the mainland, which has more in common with England, Wales and Ireland. We argue that climate shocks disrupt existing subsistence patterns, to which varied responses are represented by divergent island and mainland patterns, both in the Late Neolithic and during the Early and Middle Bronze Age. Favourable climates encouraged population growth and subsistence innovation, such as at the start of the Neolithic and in the Beaker period.
Proceedings of the National Academy of Sciences of the United States of America, Jan 29, 2014
Recent increases in archaeobotanical evidence offer insights into the processes of plant domestic... 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 ...
The period from the late third millennium BC to the start of the first millennium AD witnesses th... 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...
This paper outlines a model for the domestication of Panicum miliaceum (broomcorn millet) in Nort... 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...
This paper presents new excavation data and new radiometric dates for Jebel Moya, south-central S... more This paper presents new excavation data and new radiometric dates for Jebel Moya, south-central Sudan. These data suggest revisions to previous chronological understandings of the site. New excavations, initiated in 2017, show a longer, more continuous occupation of the site than has been previously recognised. Archaeozoological and archaeobotanical analyses provide evidence for domesticated taxa. Archaeobotanical evidence is dominated by domesticated sorghum (Sorghum bicolor), radiocarbon dated to c. 2550-2210 BC. Faunal remains include cattle and goat/sheep. A late third-millennium BC date on the human skeleton excavated in the 2017 season also shows that mortuary activity began early in the site's history, contemporary with domesticated faunal and botanical remains. These initial results indicate the long-term association of the site with pastoralism and agriculture and with environmental change. Jebel Moya's continued potential to serve as a chronological and cultural reference point for future studies in south-central Sudan and the eastern Sahel is reinforced.
Interdisciplinaria Archaeologica - Natural Sciences in Archaeology
High Resolution X-Ray Computed Tomography (HRXCT) offers a powerful 3-dimensional, nondestructive... more High Resolution X-Ray Computed Tomography (HRXCT) offers a powerful 3-dimensional, nondestructive and non-invasive diagnostic tool for imaging the external and internal structures of a range of specimens of interest including archaeobotanical remains. HRXCT offers new possibilities in terms of the research questions which may be asked of fragile and valuable archaeological and specifically archaeobotanical material. This technology, although currently somewhat limited in terms of time and access to beamtimes at National Synchrotrons, requires simple, non-destructive preparation of samples and produces exciting results. Based upon two rounds of successful work, we believe that this new methodology has wider implications and utility for advancing the field of imaging, and investigating aspects of plant domestication such as internal anatomical changes.
We report archaeobotanical results from systematic flotation at what is presently the earliest Ne... more We report archaeobotanical results from systematic flotation at what is presently the earliest Neolithic site with hard evidence for crop cultivation in the Southwestern Chinese province of Yunnan, at the site of Baiyangcun. Direct AMS dates on rice and millet seeds, included together in a Bayesian model, suggests that sedentary agricultural occupation began ca. 2650 BCE, with cultivation of already domesticated rice (Oryza sativa), broomcorn millet (Panicum miliaceum), and foxtail millet (Setaria italica). Soybean (Glycine cf. max) was also present and presumably cultivated, although it still resembles its wild progenitor in terms of seed size. Additional possible cultivars include melon (Cucumis melo) and an unknown Vigna pulse, while wild gathered resources include fruits and nuts, including hawthorn (Crateagus) and aquatic foxnut (Euryale ferox). Weed flora suggests at least some rice was cultivated in wet (flooded or irrigated fields), while dryland weeds may derive from millet fields. This subsistence system persisted throughout the site's occupation, up to ca. 2050 BCE. These data provide secure evidence for the spread of Chinese Neolithic crops to Yunnan, and provide new evidence for reconstructing possible sources of cereal agriculture in mainland Southeast Asia.
The transition to urbanism has long focused on annual staple crops (cereals and legumes), perhaps... more The transition to urbanism has long focused on annual staple crops (cereals and legumes), perhaps at the expense of understanding other changes within agricultural practices that occurred between the end of the initial domestication period and urbanisation. This paper examines the domestication and role of fruit tree crops within urbanisation in both Western Asia and China, using a combination of evidence for morphological change and a database that documents both the earliest occurrence of tree fruit crops and their spread beyond their wild range. In Western Asia the domestication of perennial fruit crops likely occurs between 6500 bc and 3500 bc, although it accompanies a shift in location from that of the earliest domestications within the Fertile Crescent to Mesopotamia, where the earliest urban societies arose. For China, fruit-tree domestication dates between ca 4000 and 2500 bc, commencing after millet domestication and rice domestication in Northern and Southern China, respectively, but within the period that led up to the urban societies that characterised the Longshan period in the Yellow River basin and the Liangzhu Culture in the Lower Yangtze. These results place the domestication of major fruit trees between the end of the domestication of staple annual crops and the rise of urbanism. On this basis it is argued that arboriculture played a fundamental role within the re-organisation of existing land use, shifting the emphasis from short-term returns of cereal crops into longer term investment in the developing agricultural landscape in both Western and East Asia. In this respect perennial tree crops can be placed alongside craft specialisation, such as metallurgy and textiles, in the formation of urban centres and the shaping the organisational administration that accompanied the rise of urbanism.
The evolution of domesticated cereals was a complex interaction of shifting selection pressures a... more The evolution of domesticated cereals was a complex interaction of shifting selection pressures and repeated episodes of introgression. Genomes of archaeological crops have the potential to reveal these dynamics without being obscured by recent breeding or introgression. We report a temporal series of archaeogenomes of the crop sorghum (Sorghum bicolor) from a single locality in Egyptian Nubia. These data indicate no evidence for the effects of a domestication bottleneck, but instead suggest a steady decline in genetic diversity over time coupled with an accumulating mutation load. Dynamic selection pressures acted sequentially to shape architectural and nutritional domestication traits, and to facilitate adaptation to the local environment. Later introgression between sorghum races allowed exchange of adaptive traits and achieved mutual genomic rescue through an ameliorated mutation load. These results reveal a model of domestication in which genomic adaptation and deterioration was not focused on the initial stages of domestication but occurred throughout the history of cultivation.
Sorghum bicolor, one of the world's five most important crops, originated in Africa. While this h... 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.
Our suggestion that agriculture was temporarily abandoned for several centuries throughout much o... more Our suggestion that agriculture was temporarily abandoned for several centuries throughout much of mainland Britain after 3600 BC has provoked criticism, notably the claim by Bishop (2015) that we have missed continuity in Scotland. We demonstrate that firm evidence for widespread agriculture within the later Neolithic is still unproven. We trace the disappearance of cereals and the associated population collapse to a probable climatic shift that impacted the abundance of rainfall and lowered temperatures, thus affecting the reliability of cereals. Divergent strategies and patterns are identified on the Scottish Islands versus the mainland, which has more in common with England, Wales and Ireland. We argue that climate shocks disrupt existing subsistence patterns, to which varied responses are represented by divergent island and mainland patterns, both in the Late Neolithic and during the Early and Middle Bronze Age. Favourable climates encouraged population growth and subsistence innovation, such as at the start of the Neolithic and in the Beaker period.
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Papers by Chris Stevens