Cameron A. Petrie

Abrupt weakening of the summer monsoon in northwest India ~4100 yr ago

Climate change has been suggested as a possible cause for the decline of urban centers of the Indus Civilization ~4000 yr ago, but extant paleoclimatic evidence has been derived from locations well outside the distribution of Indus settlements. Here we report an oxygen iso- tope record of gastropod aragonite (δ 18 O a ) from Holocene sediments of paleolake Kotla Dahar (Haryana, India), which is adjacent to Indus settlements and documents Indian summer mon- soon (ISM) variability for the past 6.5 k.y. A 4‰ increase in δ 18 O a occurred at ca. 4.1 ka mark- ing a peak in the evaporation/precipitation ratio in the lake catchment related to weakening of the ISM. Although dating uncertainty exists in both climate and archaeological records, the drought event 4.1 ka on the northwestern Indian plains is within the radiocarbon age range for the beginning of Indus de-urbanization, suggesting that climate may have played a role in the Indus cultural transformation.

Assessing the effects of volcanic disasters on human settlement in the Willaumez Peninsula, Papua New Guinea: a Bayesian approach to radiocarbon calibration

Bayesian statistical approaches to calibrating radiocarbon determinations can make a significant contribution to disaster studies by adding precision to the dating of both the environmental forcing agent and the consequent human responses. An archaeological case study in the Willaumez Peninsula region of New Britain, Papua New Guinea uses radiocarbon dating to examine the chronology of five major volcanic events and the timing and nature of recolonization. The results demonstrate the general applicability of Bayesian-based approaches for building a sound tephrochronology and for evaluating the impacts of volcanic hazards on human history.

Adaptation to Variable Environments, Resilience to Climate Change: Investigating Land, Water and Settlement in Indus Northwest India

This paper explores the nature and dynamics of adaptation and resilience in the face of a diverse and varied environmental and ecological context using the case study of South Asia’s Indus Civilization (ca. 3000–1300 BC). Most early complex societies developed in regions where the climatic parameters faced by ancient subsistence farmers were varied but rain falls primarily in one season. In contrast, the Indus Civilization developed in a specific environmental context that spanned a very distinct environmental threshold, where winter and summer rainfall systems overlap. There is now evidence to show that this region was directly subject to climate change during the period when the Indus Civilization was at its height (ca. 2500–1900 BC). The Indus Civilization, therefore, provides a unique opportunity to understand how an ancient society coped with diverse and varied ecologies and change in the fundamental environmental parameters. This paper integrates research carried out as part of the Land, Water and Settlement project in northwest India between 2007 and 2014. Although coming from only one of the regions occupied by Indus populations, these data necessitate the reconsideration of several prevailing views about the Indus Civilization as a whole and invigorate discussion about human-environment interactions and their relationship to processes of cultural transformation.

Journey to the east: Diverse routes and variable flowering times for wheat and barley en route to prehistoric China

Today, farmers in many regions of eastern Asia sow their barley grains in the spring and harvest them in the autumn of the same year (spring barley). However, when it was first domesticated in southwest Asia, barley was grown between the autumn and subsequent spring (winter barley), to complete their life cycles before the summer drought. The question of when the eastern barley shifted from the original winter habit to flexible growing schedules is of significance in terms of understanding its spread. This article investigates when barley cultivation dispersed from southwest Asia to regions of eastern Asia and how the eastern spring barley evolved in this context. We report 70 new radiocarbon measurements obtained directly from barley grains recovered from archaeological sites in eastern Eurasia. Our results indicate that the eastern dispersals of wheat and barley were distinct in both space and time. We infer that barley had been cultivated in a range of markedly contrasting environments by the second millennium BC. In this context, we consider the distribution of known haplotypes of a flowering-time gene in barley, Ppd-H1, and infer that the distributions of those haplotypes may reflect the early dispersal of barley. These patterns of dispersal resonate with the second and first millennia BC textual records documenting sowing and harvesting times for barley in central/eastern China.

Exploring Indus crop processing: combining phytolith and macrobotanical analyses to consider the organisation of agriculture in northwest India c. 3200–1500 bc

This paper presents a preliminary study combining macrobotanical and phytolith analyses to explore crop processing at archaeological sites in Haryana and Rajasthan, northwest India. Current understanding of the agricultural strategies in use by populations associated with South Asia’s Indus Civilisation (3200–1900 bc) has been derived from a small number of systematic macrobotanical studies focusing on a small number of sites, with little use of multi-proxy analysis. In this study both phytolith and macrobotanical analyses are used to explore the organisation of crop processing at five small Indus settlements with a view to understanding the impact of urban development and decline on village agriculture. The differing preservation potential of the two proxies has allowed for greater insights into the different stages of processing represented at these sites: with macrobotanical remains allowing for more species-level specific analysis, though due to poor chaff presentation the early stages of processing were missed; however these early stages of processing were evident in the less highly resolved but better preserved phytolith remains. The combined analyses suggests that crop processing aims and organisation differed according to the season of cereal growth, contrary to current models of Indus Civilisation labour organisation that suggest change over time. The study shows that the agricultural strategies of these frequently overlooked smaller sites question the simplistic models that have traditionally been assumed for the time period, and that both multi-proxy analysis and rural settlements are deserving of further exploration.

Feeding ancient cities in South Asia: dating the adoption of rice, millet and tropical pulses in the Indus civilisation

Abstract The first direct absolute dates for the exploitation of several summer crops by Indus populations are presented here. These include rice, millets and three tropical pulse species at two settlements in the hinterland of the urban site of Rakhigarhi. The dates confirm the role of native summer domesticates in the rise of Indus cities. They demonstrate that, from their earliest phases, a range of crops and variable strategies, including multi-cropping, were used to feed different urban centres. This has important implications for understanding the development of the earliest cities in South Asia, particularly the organisation of labour and provisioning throughout the year.

Quantitative historical analysis uncovers a single dimension of complexity that structures global variation in human social organization

Significance Do human societies from around the world exhibit similarities in the way that they are structured and show commonalities in the ways that they have evolved? To address these long-standing questions, we constructed a database of historical and archaeological information from 30 regions around the world over the last 10,000 years. Our analyses revealed that characteristics, such as social scale, economy, features of governance, and information systems, show strong evolutionary relationships with each other and that complexity of a society across different world regions can be meaningfully measured using a single principal component of variation. Our findings highlight the power of the sciences and humanities working together to rigorously test hypotheses about general rules that may have shaped human history. Do human societies from around the world exhibit similarities in the way that they are structured, and show commonalities in the ways that they have evolved? These are long-standing questions that have proven difficult to answer. To test between competing hypotheses, we constructed a massive repository of historical and archaeological information known as “Seshat: Global History Databank.” We systematically coded data on 414 societies from 30 regions around the world spanning the last 10,000 years. We were able to capture information on 51 variables reflecting nine characteristics of human societies, such as social scale, economy, features of governance, and information systems. Our analyses revealed that these different characteristics show strong relationships with each other and that a single principal component captures around three-quarters of the observed variation. Furthermore, we found that different characteristics of social complexity are highly predictable across different world regions. These results suggest that key aspects of social organization are functionally related and do indeed coevolve in predictable ways. Our findings highlight the power of the sciences and humanities working together to rigorously test hypotheses about general rules that may have shaped human history.

‘Multi-cropping’, Intercropping and Adaptation to Variable Environments in Indus South Asia

Past human populations are known to have managed crops in a range of ways. Various methods can be used, singly or in conjunction, to reconstruct these strategies, a process which lends itself to the exploration of socio-economic and political themes. This paper endeavours to unpack the concept of ‘multi-cropping’ by considering diversity and variation in the cropping practices of the populations of South Asia’s Indus Civilisation. It argues that nuanced interpretations of the evidence provided by the combinations of crop seeds and weeds present in specific contexts and phases of occupation can reveal much about Indus cropping strategies, which in turn enables consideration of issues related to adaptation, intensification and resilience in the face of changing social, political, economic and environmental climates.

The topographic and environmental context of the earliest village sites in western South Asia

Researchers in several continents have found that agriculture began not in major river valleys but up in the hills, where early farmers tended crops on alluvial fans and improved irrigation by building earth barriers across them. Here the authors reveal a similar process in the hills of Baluchistan and Khyber Pakhtunkhwa, where early farming villages overlook the plains of the Punjab and Sindh, heartland of the later Indus civilisation. Today this is a troubled border zone, with difficult access on the ground, but our researchers make exemplary use of satellite survey to map the villages in their specific local environments.

Expanding the research parameters of geoarchaeology: case studies from Aksum in Ethiopia and Haryana in India

A wide-ranging geoarchaeological approach is put forward using two case studies in northern highland Ethiopia at Aksum and in Haryana province of northwestern India where the authors are part of collaborative archaeological research projects. Geoarchaeological approaches are well placed to underpin archaeological project design and contribute to the understanding and modelling of the human ecosystem legacy. There is also the potential to use that data to both inform wider audiences of the importance of long-term land-use dynamics in shaping our landscapes today and influencing modern land-use policy and implementation.