Publications
The Nile and Climate History, 3000 BCE to 30 BCE
Heritage, 2025
The relationship between Nile flood variability and Egyptian political stability has been studied since Barbara Bell’s pioneering work in the 1970s, yet precise causal mechanisms linking environmental stress to societal crisis have remained elusive due to chronological limitations. This paper presents a methodological framework achieving annual to decadal resolution through volcanic forcing of the East African Monsoon. Large volcanic eruptions disrupt atmospheric circulation, suppressing monsoon rainfall over the Ethiopian Highlands and reducing Nile summer floods with impacts precisely dated through ice core chronologies (±1–2 years). Applied to Ptolemaic Egypt (305–30 BCE), this methodology demonstrates that volcanic-induced flood failures significantly increased revolt probability (p < 0.02) and correlated with land sales, warfare cessations, and economic stress indicators. Statistical validation distinguishes causal relationships from chance correlations, while comparative analysis of early versus late Ptolemaic responses reveals how political legitimacy, fiscal capacity, and institutional strength determined societal resilience versus vulnerability to environmental shocks. This approach achieves temporal resolution beyond the century-scale resolution of previous studies, determining temporal sequence essential for establishing causation. The methodology is replicable across historical contexts where documentary sources overlap with ice core volcanic chronologies, offering a template for integrating paleoclimatic precision with historical analysis to understand human–environment interactions in past societies.
Nile floods reveal Ancient Egypt's pattern of revolts
Preprint, 2025
The Nile River’s annual flood sustained Egyptian agriculture for millennia, overflowing its banks and enabling gravity-fed irrigation in a desert climate1,2. Consequently, poor flood years could produce severe agricultural failures, which are hypothesized to have promoted civil unrest during the famous Ptolemaic era (305–30 BCE)3–5. Here we show, using a novel two-dimensional hydraulic model of the Egyptian Nile, that even moderate flow reductions produced large declines in feasibly irrigated area, but with marked regional variation. These impacts were more frequent in the Thebaid region, where minor flow reductions would exclude much of the agricultural land from irrigation. By contrast, irrigation in Middle Egypt would remain stable under moderate flow reductions but faced catastrophic losses during rare, extreme droughts. These findings align with historical records of societal unrest and help explain the Thebaid’s repeated role in originating revolt movements. Further, our findings contextualize the human impact of the many major volcanic eruptions during the Ptolemaic period, which would have produced multi-year catastrophic agricultural failures across the entire region 6. This work demonstrates how external climate shocks likely cascaded through societies dependent on floodplain agriculture and highlights the vulnerability of historical administrative systems to environmental stress.
Kingship, not Monarchy. Some New Directions in the Study of Hellenistic Kingship
Hellenistic Monarchies in the Mediterranean World, 2024
The principal concern of Ptolemaic rule was the extraction of resources necessary for sustaining the court and especially for making war with the goal of acquiring further resources. To this end, kings acted as executives-in-chief overseeing a court bureaucracy largely responsible for formulating the edicts that negotiated the competing interests of many groups and institutions, some native, some naturalized. Factors beyond administrative control, such as drought, famine, and consequent internal unrest, stressed the image that prosperity flowed from the divine guidance of kings, requiring blame to be assigned to failures on the part of institutions that made up the Ptolemaic enterprise.
Investigating hydroclimatic impacts of the 168–158 BCE volcanic quartet and their relevance to the Nile River basin and Egyptian history
Climate of the Past, 2023
The Ptolemaic era (305–30 BCE) is an important period of Ancient Egyptian history known for its material and scientific advances, but also intermittent political and social unrest in the form of (sometimes widespread) revolts against the Ptolemaic elites. While the role of environmental pressures has long been overlooked in this period of Egyptian history, ice-core-based volcanic histories have identified the period as experiencing multiple notable eruptions, and a repeated temporal association between explosive volcanism and revolt has recently been noted. Here we analyze the global and regional (Nile River basin) hydroclimatic response to a unique historical sequence of four large and closely timed volcanic eruptions (first a tropical one, followed by three extratropical northern hemispheric events) between 168 and 158 BCE, a particularly troubled period in Ptolemaic history for which we now provide a more detailed hydroclimatic context. The NASA (National Aeronautics and Space Administration) GISS (Goddard Institute for Space Studies) ModelE2.1 Earth system model simulates a strong radiative response with a radiative forcing (top of atmosphere) of −7.5 W m−2 (following the first eruption) and −2.5 W m−2 (after each of the three remaining eruptions) at a global scale. Associated with this, we observe a global surface cooling of the order of 1.5 ∘C following the first (tropical) eruption, with the following three extratropical eruptions extending the cooling period for more than 15 years. Consequently, this series of eruptions is observed to constrain the northward migration of the inter-tropical convergence zone (ITCZ) during the Northern Hemisphere summer monsoon season, and major monsoon zones (African, South Asian, and East Asian) were seen to experience a suppression of rainfall of >1 mm d−1 during the monsoon (JJAS) season averaged for 2 years after each eruption. A substantial suppression of the Indian and North African summer monsoon (over the Nile River headwater region) was seen to strongly affect the modeled river flow in the catchment and discharge at river mouth. River mass flow over the basin was observed to decrease by 29 % and 38 % relative to an unperturbed (non-volcanic) annual mean flow in the first and second year, respectively, after the first (i.e., tropical) eruption. A moderate decrease ranging between 5 % and 18 % was observed after the third and fourth (extratropical) eruptions. These results indicate, in sum, that the first eruption likely produced a strong hydroclimate response, with the following extratropical eruptions prolonging this. These results also support the recently hypothesized association between ice-core-based signals of explosive volcanism and hydroclimatic variability during the Ptolemaic era, including the suppression of the agriculturally critical Nile summer flooding.
Reply to Strunz and Braeckel: Agricultural failures logically link historical events to extreme climate following the 43 BCE Okmok eruption
Proceedings of the National Academy of Sciences, 2022
We report ice core evidence that unambiguously identifies massive sulfur fallout over much of the Arctic, attributed using tephra geochemistry to eruption of Alaska’s Okmok volcano, with climate model simulations indicating 2 y of extreme temperatures and precipitation throughout the Northern Hemisphere starting in early 43 BCE. This climate event occurred in the waning years of the Roman Republic and Ptolemaic Kingdom during a period of well-known social, political, and economic stress including food shortages, epidemic disease, and unusually inclement weather reported in ancient sources. We contend that such a climate anomaly—corroborated by paleoclimate proxies—undoubtedly contributed to historical events primarily through disruptions in food production in the Mediterranean region. Without offering any specific criticisms or substantive alternatives, Strunz and Braeckel disagree with our contention.
Extreme climate after massive eruption of Alaska’s Okmok volcano in 43 BCE and effects on the late Roman Republic and Ptolemaic Kingdom
Proceedings of the National Academy of Sciences, 2020
The assassination of Julius Caesar in 44 BCE triggered a power struggle that ultimately ended the Roman Republic and, eventually, the Ptolemaic Kingdom, leading to the rise of the Roman Empire. Climate proxies and written documents indicate that this struggle occurred during a period of unusually inclement weather, famine, and disease in the Mediterranean region; historians have previously speculated that a large volcanic eruption of unknown origin was the most likely cause. Here we show using well-dated volcanic fallout records in six Arctic ice cores that one of the largest volcanic eruptions of the past 2,500 y occurred in early 43 BCE, with distinct geochemistry of tephra deposited during the event identifying the Okmok volcano in Alaska as the source. Climate proxy records show that 43 and 42 BCE were among the coldest years of recent millennia in the Northern Hemisphere at the start of one of the coldest decades. Earth system modeling suggests that radiative forcing from this massive, high-latitude eruption led to pronounced changes in hydroclimate, including seasonal temperatures in specific Mediterranean regions as much as 7 °C below normal during the 2 y period following the eruption and unusually wet conditions. While it is difficult to establish direct causal linkages to thinly documented historical events, the wet and very cold conditions from this massive eruption on the opposite side of Earth probably resulted in crop failures, famine, and disease, exacerbating social unrest and contributing to political realignments throughout the Mediterranean region at this critical juncture of Western civilization.
Volcanic suppression of Nile summer flooding triggers revolt and constrains interstate conflict in ancient Egypt
Nature Communications, 2017
Volcanic eruptions provide tests of human and natural system sensitivity to abrupt shocks because their repeated occurrence allows the identification of systematic relationships in the presence of random variability. Here we show a suppression of Nile summer flooding via the radiative and dynamical impacts of explosive volcanism on the African monsoon, using climate model output, ice-core-based volcanic forcing data, Nilometer measurements, and ancient Egyptian writings. We then examine the response of Ptolemaic Egypt (305–30 BCE), one of the best-documented ancient superpowers, to volcanically induced Nile suppression. Eruptions are associated with revolt onset against elite rule, and the cessation of Ptolemaic state warfare with their great rival, the Seleukid Empire. Eruptions are also followed by socioeconomic stress with increased hereditary land sales, and the issuance of priestly decrees to reinforce elite authority. Ptolemaic vulnerability to volcanic eruptions offers a caution for all monsoon-dependent agricultural regions, presently including 70% of world population.
Quantitative Historical Analysis Uncovers a Single Dimension of Complexity that Structures Global Variation in Human Social Organization
Proceedings of the National Academy of Sciences, 2017
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.
Various Chapters
The Encyclopedia of Ancient History, 2012
Apollonios, Ptolemaic Minister
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Demotic, Legal Texts
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Elephantine, Ptolemaic and Roman
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Hydraulic Civilization
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Money, Ancient Near East and Pharaonic Egypt
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Nubia
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Royal Land
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Syene
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Thebes (Diospolis Magna), Ptolemaic and Roman periods
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Land and Power in Ptolemaic Egypt: The Structure of Land Tenure
Cambridge University Press, 2009
By revealing the dynamics between central and local power in Egypt, Joe Manning demonstrates that Ptolemaic economic power ultimately shaped Roman Egyptian social and economic institutions. His book offers a framework for understanding the structure of the Ptolemaic state and economy, as well as the relationship between the new Ptolemaic economic institutions and the ancient Egyptian legal traditions of property rights. Historians of Egypt and the Hellenistic world will welcome the volume.
État et irrigation en Égypte antique
Cambridge University Press, 2002
In this paper I examine the relationship between irrigation and the ancient Egyptian State. Despite the persistence of the theory of the hydraulic bureaucracy developed by Engels, Marx, and Weber, and the so-called “hydraulic hypothesis” of Wittfogel, there is no evidence that connects the irrigation system to a “despotic” form of government in ancient Egypt. The ideology of centralized control must be carefully distinguished from the diffused nature of water control. For most of its history, the exploitation of the land in Egypt was organized in low-lying basins, and irrigation of the fields followed the rhythm of the annual flood and its recession. It was not until the 19th-century CE, with the concept of a mercantilist State and the use of barrages and weirs, and cash crops of cotton and sugar cane, that perennial irrigation became commonplace. Artificial irrigation is known from the beginning of the unified State (ca. 3100 BCE), but its use was limited until Roman times. This general understanding of the relationship of irrigation to the State has important implications for the understanding of the Ptolemaic intervention in Egypt. Despite the earlier central planning or etatist model of the Ptolemaic State, the Ptolemaic agrarian economy, as it was earlier, was reactive rather more than it was planned, and used a localized administrative structure to tax agricultural production.
The Scribe of Thebais: a Correction
Chronique d’Égypte, 1997
The Chronique d’Égypte has been published annually every year since 1925 by the Association Égyptologique Reine Élisabeth (formerly the Fondation Égyptologique Reine Élisabeth) sponsored by the Ministry of Education and the Fondation Universitaire de Belgique. Originally published as a newsletter, it quickly evolved into an international scientific journal containing articles on various aspects of Egyptology, papyrology and coptology (including philology, history, archaeology, and history of art) as well as critical reviews of recently published books. The articles are written by experts of various nationalities.
Egypt: Demotic Law
A History of Ancient Near Eastern Law
The first comprehensive survey of the world's oldest known legal systems, this collaborative work of twenty-two scholars covers over 3,000 years of legal history of the Ancient Near East. Each of the book's chapters represents a review of the law of a particular period and region, e.g. the Egyptian Old Kingdom, by a specialist in that area. Within each chapter, the material is organized under standardized legal categories (e.g. constitutional law, family law) that make for easy cross-referencing. The chapters are arranged chronologically by millennium and within each millennium by the three major politico-cultural spheres of the region: Egypt, Mesopotamia, and Anatolia and the Levant. An introduction by the editor discusses the general character of Ancient Near Eastern Law.
Hellenistic Egypt
The Cambridge Economic History of the Greco-Roman World, 2008
I treat here the internal economic history of the Ptolemaic dynasty, the longest lived of the Hellenistic successor states, leaving aside the Ptolemaic empire (relevant to the first half of the period, or roughly from 330–168 bc), the role of military conquest (its expenditure and revenue), and international trade. The following can in no way stand for a synthesis. Much important work is underway, or about to appear, on various aspects of the Ptolemaic economy, and there is still considerable unpublished material, particularly written in Demotic Egyptian, which bears on the understanding of the economy. The period was remarkable in the economic history of the Mediterranean, when Greek immigrants’ institutions were integrated with ancient modes of production and social organization. Like the Seleucid dynasty, the Ptolemies established themselves on a Persian foundation and provided a new incentive structure for state service and private economic activity. Egypt had been an important trade axis connecting the Mediterranean to the east and south for a millennium before the Ptolemies, but Greek immigration, the new city of Alexandria, and Greek institutions had profound effects.
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Despite the relative abundance of documentation, much remains unclear or uncertain with respect to revenue and expenditure, and thus, there are severe limits to the quantification of performance. Some subjective measures are possible. The building of new urban centers at Alexandria and Ptolemais, the founding of new villages (especially in the Fayyum), and the construction of new temples is one obvious measure of expansion. The most serious absence of evidence is our restricted knowledge of the Greek urban centers (Alexandria, Naucratis, Ptolemais).
