The Holocene

At some point during the Holocene, human action began to accelerate or redirect landscape and biospheric evolution. Basic questions for this preface are whether we should define this new dynamism as an ‘Anthropocene era’ and how might it be delimited with respect to absolute time or to the Holocene. Traditional geo-stratigraphic nomenclature developed through accretion of field observations, vetted by theoretical discussion, to facilitate four-dimensional reference to lithology, topography, space, and time. Current notions for an Anthropocene carry additional connotations: (1) the focus is on a more dynamic agenda that is far from being synthesized; (2) this revolves around the increasingly salient role of cultural agents that selectively shape a multitude of small and large specific areas, so as to favor divergences and disjunctures; (3) the result is a non-normative dynamic of changing spatial configuration and temporal scales that was superimposed on non-cultural Holocene processes predominantly steered by ‘natural’ forces; and (4) this would argue for a flexible, time-transgressive concept, rather than a firm time-frame, that should stimulate identification and investigation of centers of early or unusual human disturbance. The amplified energy and amplitude of these culturally modified divergences are formidable, but Pleistocene glaciation posed a more severe test for biotic evolutionary success than did past or current global change driven by human actions. This would suggest that instead of proclaiming alarmist schedules, we should concentrate on constructive research and university instruction that better emphasizes environmental and sociocultural resilience, adaptation, and the interplay of buffering feedbacks with systemic micro-evolution.

When is the baseline for Anthropocene? The first indications of human impact on earth closely relate to early human behavior and use of resources. First agricultural societies modified the landscape with the aim of generating their own resources to satisfy the needs of an increasing population. This new system was the result of years of learning and continuous interaction with landscape. Hunter-gatherer societies had shown a vast knowledge of their surrounding environment, which allowed them to exploit and optimize the available resources. But, had these societies the capacity to modify the landscape in such a way that can be traced up until today? How far back in time can we go to find the first evidence of human impact on earth? In this paper, we will try to analyze early human behavior and the possible impact of their activities on the landscape. We will use the paleoanthropological site of Olduvai Gorge (northern Tanzania) as a case study to suggest that the baseline for Anthropocene, taking the term as human impact on earth through cognitive-behavioral strategies, can be moved back to the time when early hominins visited Olduvai. Olduvai Gorge is perfectly suited for this study since the latest scientific research and publications have yielded a detailed knowledge of the vegetation, the landscape, and of the wildlife that lived in the area.

The ecological impacts of human activities have infiltrated the whole of the ‘natural world’ and precipitated calls for a newly defined geological epoch – the Anthropocene. While scholars discuss tipping-points and scale, viewed over the longue durée, it is becoming clear that we have inherited the compounding consequences of a constructed environment with a long history of human landscape modification. By linking phytolith and micro-charcoal evidence from sediments in the Azraq Basin, Jordan, we discuss potential Early Epipaleolithic (23,000–17,400 cal. BP) human–environment interactions in this wetland. Our analyses reveal that during the Last Glacial Maximum, Levantine hunter-gatherers could have had a noticeable and increasing impact on their environment. However, further work needs to be undertaken to assess the range, frequency, intensity, and intentionality of marsh disturbance events. We suggest that the origin of ‘persistent places’ and larger aggregation settlements in the Azraq Basin may have been, in part, facilitated by human–environment interactions in the Early Epipaleolithic that consequently enhanced the economic and, subsequently, social meaning of that landscape. Through their exploitation of the sensitive wetland environment, hunter-gatherers were modifying the marshes and initiating long-term changes to the already dynamic and changing landscape at the close of the Pleistocene. These findings challenge us to further reconsider the way we see early hunter-gatherers in the prehistory of the Levant and in the development of the ‘Anthropocene’.

Palynological archives dating from the Pleistocene–Holocene transition are scarce in the arid zone of the southern Levant. Anthracological remains (the carbonized residues of wood fuel use found in archaeological habitation sites) provide an alternative source of information about past vegetation. This paper discusses new and previously available anthracological datasets retrieved from excavated habitation sites in the southern Levant dating to the Pre-Pottery Neolithic (PPN) period. The available evidence indicates the existence of distinct arboreal floras growing in different ecological niches, which occupied areas that today are either treeless or very sparsely wooded. The anthracological data provide independent confirmation of the hypothesis that early Holocene climate in the southern Levant was significantly moister than at present. Clear North–South and East–West precipitation and associated woodland composition gradients are evidenced. Far from deducing widespread anthropogenic degradation of the regional vegetation, it is suggested that woodland expansion in the semi-arid interiors of the Levant may be attributed to the intensive management of Pistacia woodlands for food, fuel and pasture.

This paper examines the hypothesis that human landscape modifications involving early agriculture contributed to greenhouse gas emissions in preindustrial times, a proposal that has significant implications for the timing of the Anthropocene era. In synthesizing recent papers that both advocate and challenge this hypothesis, we identify a major bias in the ongoing debate, which focuses on the land clearance practices of agrarian people, with insufficient consideration of a diverse range of hunter-gatherer societies who regularly utilized landscape-scale burning for various purposes. Employing California as a case study, we examine how the exclusion of hunter-gatherers from this debate may have shortchanged estimates of human biomass burning in preindustrial times. We also suggest that human population size may be a poor proxy for the degree of land clearance and anthropogenic burning, and we describe how previous approaches to these questions may have underplayed the importance of variation in the timing and magnitude of depopulation in different regions of the Americas.

The nature and spatial scale of prehistoric human landscape modifications in Amazonia are enduring questions. Original conceptions of the issues by archaeologists published more than 40 years ago posited little human influence because of putative environmental constraints. Empirical data accumulated more recently demonstrated dense, permanent settlements along major watercourses of the central and southern Amazon, and profound landscape alterations in seasonally flooded savanna regions of Bolivia. These results led some investigators to propose that most to all of Amazonia was heavily populated and modified before European arrival, and that prehistoric fires and forest clearing were of such a massive scale that post-Columbian reforestation was a significant contributor to decreasing atmospheric CO₂ levels and the onset of the ‘Little Ice Age’. Recent data generated from investigations of soils sampled from underneath standing terra firme forests in parts of the western Amazon indicate ephemeral ancient human occupation and little vegetation disturbance there. These issues are central to ongoing discussions surrounding the classification and timing of the Anthropocene, because a geological epoch proposed on the basis of profound human alteration of environments and considerations of when during the Holocene it should begin, require robust paleo-environmental and archaeological data from major, critically important zones such as the Amazon Basin. This paper reviews debates and existing information on prehistoric human influences in Amazonia, provides new data from the western Amazon, and attempts to arrive at reasonable conclusions based on the available empirical data.

Despite evidence for the protracted presence of humans in the Amazon Basin, its vast interfluvial habitats are frequently depicted as having survived until recently as ‘wild’ landscapes with neither human settlement nor substantial human land use. Related research interests of paleoecology and archaeology share parallel histories in the development of explanatory paradigms for understanding processes contributing to neotropical ecology, as both emerged from earlier periods dominated by models based on stability and equilibrium to a contemporary advocacy of dynamic stability and change. Recent paradigms accommodate humans as keystone species and implicate their role in past and present landscape management. This is particularly important in the neotropics where it is argued that an extensive and ancient indigenous agroforestry employed intermediate disturbance in the management of interfluvial landscapes. This is contrasted with a critical discussion of recent paleoecological research in central and western Amazonia, which argues that interfluvial landscapes were devoid of pre-Columbian populations and survived as relatively pristine relic landscapes throughout most of the Anthropocene.

Islands are traditionally considered sensitive to environment and climate change. The Caribbean Islands are a biodiversity hotspot, where conservation efforts should be a priority. However, the archaeological record suggests that the biotic characteristics of the islands, even within nature or forests reserves, are strongly shaped by thousands of years of intense human activity. This presents an issue for conservation efforts because defining what should be preserved and what should be reconstructed is not straightforward. Using Puerto Rico as case study, this article explores how socioecosystem dynamics influenced the biotic characteristics of the island at specific archaeological periods and to what extent these processes have affected the environmental resources on the island today. Climatic data, its implications on forest type and cover, and landscape characteristics as seen from sedimentary records, combined with archaeological data on human–environment interactions over time, from the mid-Holocene to the present are used to investigate these themes. This article brings forth more questions than answers, but it reflects the status of deep-time environmental research on the island, which is still in its early stages. I argue that, starting from the earliest occupations, human influence has altered the ecology of Puerto Rico so deeply that the natural resources we work toward preserving, conserving, or restoring today cannot be understood without considering the social contexts that shaped them. In this sense, if the Anthropocene is a proposal to rename the current geological period because of the overwhelming physical evidence of change that human activity has left behind, then the history of the Puerto Rico supports the proposal for the application of the term since at least 5 ka. Applying the concept would bring the relevance of human activity to the forefront, contributing to the reconsideration of the role of humans in the formation and preservation of modern ecological systems.

This is the first article to characterize the soil and fluvial geomorphology of the Rio Bravo’s fluviokarst watershed in the Rio Bravo Conservation and Management Area, northwestern Belize. Although the watershed has had little-altered tropical forest cover since c. 1000 BP, humans inhabited it for millennia, especially during the Maya Preclassic and Classic, c. 3000–1000 BP. We studied soils and floodplain formation in four excavation transects in the Rio Bravo to understand long-term human impacts on this watershed. Archaic to Preclassic (c. 3000–1700 BP) sedimentation rates ranged from 0.82 mm yr⁻¹ at Chawak But’o’ob to 1.5 mm yr⁻¹ on the Gran Cacao floodplain. The late Preclassic through Classic (c. 2300–1000 BP) rates rose 0.98–2.03 mm yr⁻¹, and the Classic (c. 1700–1000 BP) rates ranged from 1 mm yr⁻¹ to as high as 9.12 and 16.27 mm yr⁻¹ at ancient Maya wetland field sites. Post Classic rates dropped back in the one dated profile, and the well-developed topsoils indicate long-term surface stability. Older soils at the edges and higher islands of the valley had more vertic features and full Vertisols, whereas Vertic Mollisols and Aquerts have formed in younger sediments. We also present new evidence for late Classic Maya wetland field formation at Chawak But’o’ob, which shows field raising with canalization in this wetland of low ionic water. All the soil profiles with dating and stable carbon isotope evidence exhibited increased δ¹³C in the profiles through the Classic period sediments, although some were equivocal. The two wetland field δ¹³C profiles through the Classic period sediments increase by c. 6‰ at Chawak But’o’ob and 3‰ at the Birds of Paradise (BOP) Field center, although earlier BOP profiles increased by as much as 7‰. Hence, this watershed exhibits three large diachronic shifts: from lower to higher and again to lower deposition over pre-Maya, Maya, and post-Maya times. These changes along with earlier evidence for ancient intensive agriculture from 3000 and 1000 BP lie sandwiched between the ancient and contemporary little-altered tropical forest.

In this paper, we use geoarchaeological and paleoenvironmental data from three localities in the Yellow River Valley, China – Taosi, Sanyangzhuang, and the Yiluo Valley – to argue that human activity in the mid- to late-Holocene contributed to large-scale changes in the behavior of the Yellow River and that these changes were of sufficient magnitude to bend the arc of China’s history. Massive anthropogenic landscape transformation from the later Neolithic into the early Dynastic periods, especially in the Chinese Loess Plateau, increased sedimentation in the Yellow River requiring intensive investment in flood control features to protect an ever-growing population. As the Yellow River channel aggraded, channel gradients became increasingly steep, and avulsions occurred with greater frequency and consequence. Flooding reached an apogee in the first decades of the Common Era when a massive avulsion of the Yellow River ca. 14–17 CE caused the river to shift to the south and east of its former channel. This avulsion and the catastrophic flooding that followed triggered the collapse of the Western Han dynasty. The Yellow River – known as ‘China’s Tribulation’ – has been seen as a natural scourge that afflicts the inhabitants of the fertile North China Plain. However, when viewed in an Anthropocene perspective, it is evident that China’s Tribulation largely is the result of human manipulation of the environment.

The Yellow River catchment of northern China was central to the rise of complex societies from the first Neolithic farmers through to early states and empires. These cultural developments brought with them rising populations and increasing intensity of land-use. This region provides an important record of landscape changes that mark the development of the Anthropocene in China. Geoarchaeological research in the middle reaches of the Yellow River catchment of Henan Province and eastward to the Si River drainage of Shandong Province illustrates human impact on vegetation and hydrological systems dating back at least until the middle Neolithic Yangshao Period in the mid-Holocene, ca. 7000 yr BP. This research provides geomorphological evidence that early human impact began in the Yangshao period with deforestation, soil erosion, and increased alluviation in the upper catchment of the Yiluo River. The increased alluviation allowed small-scale Neolithic farmers to intensify and supplement their production with rice paddy farming. Further east along the Si River of Shandong Province, Neolithic Dawenkou farmers were intensifying production by taking advantage of the already moist floodplains, but had little impact on the surrounding forests and hillslopes. At the beginning of the Zhou Period (ca. 1000 BCE), farmers along the Si River at Qufu began to intensify production by digging canals into the floodplain, and deforestation of the hillslopes led to the beginnings of widespread floods and silty floodplain buildup, culminating in the massive destructive floods of the later Han Period characterized by thick sand beds.

A multiproxy record from Lake Parishan, SW Iran, shows human impact on the lake and its catchment over the last 4000 years. The Parishan record provides evidence of changes in lake hydrology, from ostracod, diatom and isotope analyses, that are directly linked to human activity in the catchment; recorded by pollen and charcoal and supported by regional archaeological and historical data. The lake ostracod fauna is particularly sensitive to human-induced catchment alterations and allows us to identify changes in catchment hydrology that are due to more than a simple change in precipitation: evaporation state. Oxygen isotope data from endogenic carbonates follow these faunal changes but also display a longer trend to more positive values through the period, coincident with regional patterns of water balance for the late-Holocene in the eastern Mediterranean.

Pre-industrial human impacts on the past environment are apparent in different proxy records at different times in different places. Recognizing environmentally transformative human impacts in palaeoenvironmental archives, as opposed to natural variability, is a key challenge in understanding the nature of the transition to the Earth’s current ‘Anthropocene’ condition. Here, we consider the palaeoenvironmental record for Iceland over the past 2.5 ka, both before and after the late ninth century human settlement (landnám). The Scandinavian colonization of the island was essentially abrupt, involving thousands of people over a short period. The colonization triggered extensive changes in Icelandic ecosystems and landscapes. A volcanic ash known as the Landnám tephra was deposited over most of Iceland immediately before the settlement began. The Landnám tephra layer thus provides a uniquely precise litho-chrono-stratigraphic marker of colonization. We utilize this marker horizon as an independent definition of the effective onset of the local palaeoanthropocene (which is conceptually related to, but distinct from, the global Anthropocene). This allows us to evaluate proxy records for human impact on the Icelandic environment and to assess how and when they show transformative impact. Based on this analysis, we consider the implications for understanding and defining the Anthropocene in those areas of the Earth where such a clear independent marker of the onset of significant human impacts is lacking.

The offshore islands of the North Atlantic were among some of the last settled places on earth, with humans reaching the Faroes and Iceland in the late Iron Age and Viking period. While older accounts emphasizing deforestation and soil erosion have presented this story of island colonization as yet another social–ecological disaster, recent archaeological and paleoenvironmental research combined with environmental history, environmental humanities, and bioscience is providing a more complex understanding of long-term human ecodynamics in these northern islands. An ongoing interdisciplinary investigation of the management of domestic pigs and wild bird populations in Faroes and Iceland is presented as an example of sustained resource management using local and traditional knowledge to create structures for successful wild fowl management on the millennial scale.

Medieval Islamic archaeology in Jordan is relevant to the ‘Anthropocene’ discourse because of state investment in intensive land use, including irrigation and diversion of local agricultural economies from subsistence crops to cash crops. Archaeology offers a deep-time perspective on these issues. Previous archaeological and historical studies indicate that major centers of Medieval agriculture deteriorated at some point during the 15th century, in part because of state economic withdrawal and this impacted land use. In this paper, we use phytoliths to understand agricultural practices of Medieval Hisban (Mediterranean vegetation zone), Tawahin as-Sukkar, Khirbet as-Sheikh Isa, and Beidha (semi-arid region of the Jordan Valley) to offer new insights into state agricultural policies in relation to ecological and environmental history. Our results show control of irrigable land by subsistence farmers gave them resilience and contributed to sustainable farming. However, state-managed agricultural systems expropriated irrigable land, emphasizing production of cash crops for state revenue, thus reducing sustainability and putting pressure on the landscape. Sugarcane production replaced cereal cultivation and led to wood fuel burning, enhancing landscape erosion. Phytoliths from Beidha indicate that intensive agricultural production extended to marginal areas with the use of irrigation, thus creating greater human impact on sensitive environments.

When Spanish colonists entered New Mexico in 1598, they encountered landscapes shaped by centuries of intensive human use: the fields, water features, and towns of prehistoric New Mexico were all products of human activity, and both zooarchaeological and paleoethnobotanical data suggest significant human impacts on floral and faunal features outside of human settlement. And yet, these human-influenced prehistoric Southwestern landscapes were distinct from those that developed through the ‘Columbian exchange’ and contact between indigenous communities and the Spanish. The Spanish colonists brought with them a suite of new taxa – both floral and faunal – as well as new land management practices that transformed New Mexican environments, eventually leading to the iconic Southwestern landscapes of today. In this paper, I use zooarchaeological data to explore New Mexican landscapes from the late prehistoric period through the early 20th century, assessing the degree of influence of Spanish fauna across this period of time.

The Dust Bowl of the 1930s was an environmental crisis of epic proportions characterized by unprecedented soil erosion, population redistribution, and profound transformation of the landscape in the Great Plains region of the United States. Therefore, one might expect that this event left a mark in the sedimentary and geomorphological record of the region. This study is a field reconnaissance of sedimentary and landscape changes that can be linked to the event. To achieve this objective, the Dust Bowl is analyzed as a climatic event, a geomorphic event, and a socioeconomic event. The geoarchaeological approach taken here is based on that of the archaeology of the contemporary past (Harrison and Schofield, 2010), which incidentally coincides with the Anthropocene, as defined by Crutzen (2002). The results of this survey can be useful to those who search for geomorphic evidence of environmental crises in the more distant past.

The Special Issue provides a deep-time interdisciplinary perspective on the Anthropocene and signals the importance of the Anthropocene concept in past, present, and future human–environmental relationships. This concluding article recognizes that various approaches – scientific, postmodern, catastrophist, and ecomarxist – can contribute to understanding the Anthropocene as a process and that contributions have been made by several disciplines, including Anthropology, Archaeology, Geography, History, and Politics. The critical importance of weaving together social science perspectives with those of the natural sciences is emphasized.