Timothy Beach | Georgetown University (original) (raw)

Papers by Timothy Beach

Geochimica et Cosmochimica Acta, 1994

AGU Fall Meeting Abstracts, Dec 1, 2019

Office of the VP for Researc

AGU Fall Meeting Abstracts, Dec 1, 2020

Proceedings of the National Academy of Sciences of the United States of America, Sep 27, 2021

Historical socioecological transformations in the global tropics as an Anthropocene analogue Penn... more Historical socioecological transformations in the global tropics as an Anthropocene analogue Penny and Beach PNAS | 3 of 8 Historical socioecological transformations in the global tropics as an Anthropocene analogue

The 81st Annual Meeting of the Society for American Archaeology, 2016

Soil Erosion Research Under a Changing Climate, January 8-13, 2023, Aguadilla, Puerto Rico, USA, 2023

Research Square (Research Square), Apr 12, 2023

Worldwide, mountain glaciers are shrinking rapidly and projected to disappear largely by 2100. Co... more Worldwide, mountain glaciers are shrinking rapidly and projected to disappear largely by 2100. Consequently, large areas are becoming available for novel alpine ecosystems. These harsh environments, however, slow down primary succession. In this study with a local community, we conducted an inclusion experiment to investigate if and how Llama glama in uences soils and vegetation primary succession following glacial retreat. At the foot of the Uruashraju glacier in the Cordillera Blanca, Peru (~ 4680 m.a.s.l.), we established four llama inclusion plots and four control plots that we studied from 2019 to 2022, 24-40 years after glacial retreat. After three years, the llama plots had signi cantly increased soil organic carbon and soil nitrogen. In the llama plots, we found a large, signi cant increase in vascular plant cover (+ 57%) between the second and third years of experimentation, and we identi ed four new species that were not present in 2019. Our results suggest that Llama glama, through their latrine behavior and role as a seed disperser, enhances the primary succession and novel ecosystem formation in recently deglaciated landscapes. Our study provides scienti c support that rewilding of native Andean camelid may favor adaptation to glacier retreat and strengthen the conservation and management of novel proglacial ecosystems.

2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014), Oct 19, 2014

Encyclopedia of earth sciences, Aug 12, 2016

Abstracts with programs, 2022

Wiley Interdisciplinary Reviews: Climate Change, Dec 28, 2021

Alpine glaciers worldwide will lose most of their volume by the end of the 21st century, placing ... more Alpine glaciers worldwide will lose most of their volume by the end of the 21st century, placing alpine ecosystems and human populations at risk. The new lands that emerge from retreating glaciers provide a host of challenges for ecological and human adaptation to climate change. In these novel proglacial landscapes, ecological succession and natural hazards interplay with local agriculture, hydroelectric production, mining activities, and tourism. Research has emphasized the importance of understanding adaptation around socio‐environmental systems, but regional and global management efforts that support local initiatives and connect novel proglacial landscapes to ecological, social, and cultural conservation opportunities are rare and nascent. The characteristics of these emerging lands reflect the nexus of alpine ecosystems with socio‐political histories. Often overlooked in glacial‐influenced systems are the interdependencies, feedbacks, and tradeoffs between these biophysical systems and local populations. There is no coordinated strategy to manage and anticipate these shifting dynamics, while affirming local practices and contexts. There is an opportunity to initiate a new conversation and co‐create a governance structure around these novel landscapes and develop a new framework suitable to the Anthropocene era. This article first synthesizes the rapid socio‐environmental changes that are occurring in proglacial landscapes. Second, we consider the need for integrating “bottom‐up” with “top‐down” approaches for the sustainable management of proglacial landscapes. Finally, we propose establishing a transdisciplinary initiative with policy‐related goals to further dialogues around the governance and sustainable management of proglacial landscapes. We call for increased cooperation between actors, sectors, and regions, favoring multiscale and integrated approaches.This article is categorized under:Climate, Ecology, and Conservation > Conservation Strategies

2012 GSA Annual Meeting in Charlotte, Nov 4, 2012

Nature Human Behaviour, 2021

City plans symbolizing cosmologies have long been recognized as a defining element of Mesoamerica... more City plans symbolizing cosmologies have long been recognized as a defining element of Mesoamerican civilizations. The origins of formal spatial configurations are thus the key to understanding early civilizations in the region. Assessment of this issue, however, has been hindered by the lack of systematic studies of site plans over broad areas. Here, we report the identification of 478 formal rectangular and square complexes, probably dating from 1,050 to 400 BC, through a lidar (laser imaging, detection and ranging) survey across the Olmec region and the western Maya lowlands. Our analysis of lidar data also revealed that the earlier Olmec centre of San Lorenzo had a central rectangular space, which possibly provided the spatial template for later sites. This format was probably formalized and spread after the decline of San Lorenzo through intensive interaction across various regions. These observations highlight the legacy of San Lorenzo and the critical role of inter-regional interaction.

Global and Planetary Change, 2016

Abstract We produced a new high-resolution absolute U–Th dated stalagmite oxygen isotope record (... more Abstract We produced a new high-resolution absolute U–Th dated stalagmite oxygen isotope record (δ 18 O) from Rio Secreto, Playa del Carmen, Yucatan Peninsula (YP). This new 1434-year stalagmite record (named Itzamna after the Maya god of creation) spans the time interval between BCE 1037 and CE 397 with an average resolution of 8 ± 2 years. It provides a novel view of climate evolution over the Preclassic and early Classic periods in Maya history. To understand the controls of regional precipitation δ 18 O on seasonal time scales, we characterized the amount effect between precipitation amount ( P ) and precipitation δ 18 O (δ P ). We found that precipitation δ 18 O in the Yucatan Peninsula is controlled by the amount effect on seasonal scales (δ P /Δ P = − 0.0137 ± 0.0031‰ per mm, r = 0.9), as suspected but never before demonstrated. Cave drip δ 18 O is consistent with the annual amount-weighted δ 18 O composition of precipitation. Multiple lines of evidence suggest that stalagmite δ 18 O reflects isotopic equilibrium conditions and thus stalagmite δ 18 O changes are interpreted to reflect precipitation amount. We determined quantitative precipitation changes from the stalagmite δ 18 O record following previous methods (Medina-Elizalde and Rohling, 2012). The stalagmite precipitation record suggests twelve periods of anomalous precipitation reductions ranging between about 30 and 70% below mean conditions at the time and with durations from 6 years to 31 years. Between BCE 520 and 166, the speleothem precipitation record suggests that the YP experienced an interval of high precipitation labeled the Late Preclassic Humid Period (LPHP) with precipitation maxima of up to + 86 ± 20%. Preclassic Maya cultural expansion in El Mirador Basin, located in northern Guatemala, took place while the peninsula transitioned from the LPHP to an interval with below average precipitation. We find that the Preclassic abandonment of major centers in the Mirador Basin and others around the Maya Lowlands was synchronous with two unprecedented multi-decadal events of severe precipitation reduction with magnitudes of − 55 ± 13% and − 49 ± 12 and centered at CE 186 and 234, respectively. We also find evidence that centennial scale precipitation variability in the YP during the Preclassic Period may have been associated with shifts in rainfall fluxes from Atlantic tropical cyclones.

Geochimica et Cosmochimica Acta, 1994

AGU Fall Meeting Abstracts, Dec 1, 2019

Office of the VP for Researc

AGU Fall Meeting Abstracts, Dec 1, 2020

Proceedings of the National Academy of Sciences of the United States of America, Sep 27, 2021

The 81st Annual Meeting of the Society for American Archaeology, 2016

Soil Erosion Research Under a Changing Climate, January 8-13, 2023, Aguadilla, Puerto Rico, USA, 2023

Research Square (Research Square), Apr 12, 2023

2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014), Oct 19, 2014

Encyclopedia of earth sciences, Aug 12, 2016

Abstracts with programs, 2022

Wiley Interdisciplinary Reviews: Climate Change, Dec 28, 2021

2012 GSA Annual Meeting in Charlotte, Nov 4, 2012

Nature Human Behaviour, 2021

Global and Planetary Change, 2016

Oxford Handbooks Online, 2016

Archaeological Review from Cambridge, 2009

Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures, 2008

Ancient Near Eastern Studies, 2001

browse categories : ... ...

Fuel and Energy Abstracts, 2011

... All the samples for Turkey come from near the Kinet Höyük Archaeological site on the eastern ... more ... All the samples for Turkey come from near the Kinet Höyük Archaeological site on the eastern Mediterranean coast ([Luzzadder-Beach and Beach, 2000], [Luzzadder-Beach and Beach, 2001], [Beach and Luzzadder-Beach, 2000], [Beach and Luzzadder-Beach, 2008], [Gates ...

A new paleoecology record from the El Palmar Cival adds to the emerging geoarchaeological record ... more A new paleoecology record from the El Palmar Cival adds to the emerging geoarchaeological record of El Zotz, Guatemala. El Palmar's 3 m stratigraphic record began in the Archaic period before 1500 B.C. at or just before initial Maya impacts. From the lowest level, Late Archaic organic deposition, with evidence for diverse tropical forest and a steady water table, transitioned to Early Preclassic clay deposition, decreased forest taxa, three known food taxa, and more economic species. Clay deposition continued through the Preclassic, with occasional organic and high charcoal deposition, increasing maize, and other possible economic pollen. Classic El Palmar saw a new land use type with continued disturbance evidence but diverse and greater forest cover. Human impacts continued, leaving high amounts of disturbance taxa, charcoal, and the highest maize pollen level, concomitant with lower deposition rates, δ 13 C evidence of increased, diverse tropical forest taxa and organic sediments. El Zotz Aguada's Early Classic to Postclassic sediment record overlaps this, with maize and squash pollen evidence changing to Classic period copal tree pollen dominance. Both records indicate the maximum quantity of C 4 taxa derived organic matter was about 40%, leaving at least half from C 3 taxa such as tropical forest species. C 2016 Wiley Periodicals, Inc.

Paleoecology of an Ancient Maya City, 2015

Ancient Mesoamerica, 2005

The Pakbeh Regional Economy Program is studying the vexing questions of economic life among the a... more The Pakbeh Regional Economy Program is studying the vexing questions of economic life among the ancient Maya in northwestern Yucatan, Mexico. The region constitutes an ideal laboratory in which to investigate these questions, as it has very limited agricultural potential and fewer options for intensification than are found in the southern and central lowlands, yet many times more people lived here during the Classic period than can eke out a living today, and it has abundant evidence of market trade. Because crop yields in outfields are very low, and known intensification techniques are possibly incapable of sufficient yield enhancement, we anticipated that it would be an easy task to demonstrate that this population was dependent on imports of food and other necessities of life from beyond the region and therefore had a complex exchange economy. Twelve years later, we report on how wrong we were. We are still struggling with an evaluation of agricultural insufficiency. We explore the many and varied lines of evidence we have pursued and the confounding factors inherent in them, including problems with reconstructing ancient population size, equating contemporary and historical crop yields and farming practices, as well as ancient with modern environmental conditions, and hypothesizing potential forms of agricultural intensification, including intensive fertilization and other yield enhancement techniques, and reliance on alternative crops. The best that we can say at this juncture is that using contemporary production and consumption standards, the most conservative population estimates, and the most liberal estimates of available land in the surrounding region, we can conclude only that regional agricultural self-sufficiency remains unlikely but not proved. What initially seemed like an archaeological "no-brainer" has required us to delve into the realm of archaeological epistemology that we would like to share with our colleagues.

Ancient Mesoamerica, 1997

The Petexbatun region has a series of upland ridges surrounded by lowland wetlands. In Preclassic... more The Petexbatun region has a series of upland ridges surrounded by lowland wetlands. In Preclassic times, ancient Maya peoples began colonizing the region along waterways. Although few in number, they cleared large areas of upland tropical forest for agriculture and induced significant soil erosion. Population contracted in the region during the Early Classic, and mature tropical forest growth returned. During the Late Classic, population expanded rapidly across the region, forest clearance resumed, and desirable, intensively cultivated, upland areas were divided by an elaborate wall system. Upland agriculture during the Late Classic included the use of several types of terracing that significantly checked soil erosion during this period. Considerable variation may have existed between the urban agriculture practiced in the region's three major centers-Dos Pilas, Tamarindito, and Aguateca.

Ancient Mesoamerica, 1998

Investigations at Punta Canbalam on the Gulf Coast of Campeche reveal it is probably the largest ... more Investigations at Punta Canbalam on the Gulf Coast of Campeche reveal it is probably the largest of several important but underreported trading sites on the pan-Mesoamerican maritime trade route. The coastline has been unstable for the last thousand years, subjecting the site to sea level changes and repeated episodes of beach erosion and redeposition. The relatively dense scatter of temporally mixed, highly weathered sherds and other artifacts on an exceedingly narrow, modern beach indicates that it is all secondarily deposited and that its original location was offshore. An interdisciplinary team is beginning to recognize clues in its environmental and cultural contexts as to where this peripatetic site was originally located and the extent to which it depended upon exchanges of salt, petty commodities from inland, and canoe-borne exotics from afar. This predominantly Terminal Classic and Early Postclassic site likely served as a port of entry for obsidian, jade, fine-paste ceramics, and other goods for the nearby inland city of Chunchucmil. It also probably supplied the interior with marine and estuarine food and ornamental and ritual products in exchange for inland agricultural products and other items.

Annals of the Association of American Geographers, 2009

Research on human and environmental interactions in the Maya Lowlands has included important case... more Research on human and environmental interactions in the Maya Lowlands has included important case studies of ancient water and soil management, impacts of climatic fluctuations, and diverse agricultural adaptations over millennia. Studies also have shed light on landscape and soil formation, including past periods of soil erosion and aggradation of several parts of these tropical lowlands. This study uses water, soils, radiocarbon, and archaeological data to determine the quantity, timing, and causes of aggradation in Belize's Three Rivers region in a series of sinks from the karst uplands into the coastal plain. Water sources in the uplands have low quantities of dissolved ions including sulfate, but water in the coastal plain has high amounts of dissolved ions and is nearly saturated in sulfate and calcium. Soil and geomorphic findings come from twenty-two excavations that uncovered more than 1,200 m of stratigraphy, representing a broader region. These extensive data serve to characterize and date stratigraphy, and exposures and four main excavations from the uplands into the wetlands of the coastal plain serve to intensively characterize soil profiles. We found that this landscape in the early to middle Maya Preclassic (1200 BC to 350 BC) was on average 1.2 m lower and mantled by what is now a distinct paleosol. From the Late Preclassic (350 BC–AD 250) to Classic periods (AD 250–900), the landscape aggraded by an average of 1.2 m from four possible sources: river flooding, local erosion, ancient Maya landscape manipulation, and gypsum precipitation from a rise in a water table nearly saturated in calcium and sulfate ions. Soil erosion is the main driver of the clastic sedimentation on upland valleys and fans, but water table rise is the main driver on the wetlands of the coastal plain because the aggraded sediments here are dominantly composed of gypsum, in which the groundwater is saturated. This latter type of aggradation, by the natural rise of a water table saturated in calcium and sulfate, represents a different mechanism from the more typical erosion-induced aggradation. This study shows that the ancient Maya confronted more natural hazards in the Classic period than just the well-known droughts of the eighth through tenth centuries AD, and in this case the Maya adapted to an environmental change so large that they had to adjust their land use strategies from well-drained to perennial wetland conditions.

The conjunctive use of paleoecological and archaeological data to document past human-environment... more The conjunctive use of paleoecological and archaeological data to document past human-environment relationships has become a theoretical imperative in the study of ancient cultures. Geographers are playing leading roles in this scholarly effort. Synthesizing both types of data, we argue that large karst depressions known as bajos in the Maya Lowlands region were anthropogenically transformed from perennial wetlands and shallow lakes to seasonal swamps between 400 bc and ad 250. This environmental transformation helps answer several questions that have long puzzled scholars of Maya civilization: (1) why many of the earliest Maya cities were built on the margins of bajos, (2) why some of these early centers were abandoned between 100 bc and ad 250, and (3) why other centers constructed elaborate water storage systems and survived into the Classic period ( ad 250-900). The transformation of the bajos represents one of the most significant and long-lasting anthropogenic environmental changes documented in the pre-Columbian New World.

Annals of the Association of American Geographers, 1994

Yearb. Conf. Lat. Am. Geogr, 1996

Located in the northwest Yucatan Peninsula, Chunchucmil was a major, densely populated Maya cente... more Located in the northwest Yucatan Peninsula, Chunchucmil was a major, densely populated Maya center during the Late Classic Period. The high population density of this site remains a mystery in light of the apparently low agricultural potential of its setting. This area today is extremely dry and the surface is covered by vast outcroppings of limestone with thin and meager soil cover. Possible answers to the Chunchucmil paradox are: 1) Chunchucmil agriculturalists used agricultural intensification techniques to increase production, and 2) Chunchucmil was involved in regional trade of coastal resources (such as salt) for food. Understanding the settlement pattern, site boundaries, and subsistence base of Chunchucmil requires extensive mapping of the settlement, including a systematic soil survey. As a precursor to an extensive program of research, we conducted a preliminary soil and environmental survey in 1994. This paper presents the results of that analysis, considers alternative agricultural practices, and suggests the direction of future research at the site.

$Research paper thumbnail of Phosphate fractionation and spatial patterning in ancient ruins: A case study from Yucatan$

CATENA, 2009

As time passes, phosphorus (P) in soils tends to become more tightly bound with minerals. Phospha... more As time passes, phosphorus (P) in soils tends to become more tightly bound with minerals. Phosphate fractionation enables the measurement of loosely versus tightly bound P. Archaeologists have used P fractionation as a chronometric technique: older soils should ...

Catena, Jan 1, 2006

Many studies across the central and southern Maya Lowlands of Belize, Guatemala, Honduras, and Me... more Many studies across the central and southern Maya Lowlands of Belize, Guatemala, Honduras, and Mexico have produced records of land degradation, mostly sedimentation and soil erosion, during the ancient Maya period from before 1000 BC to the Maya Collapse of c. AD 900. This paper provides new data from two sites (Blue Creek and Cancuén), synthesizes more than a decade of the authors' research in Guatemala, Belize, and Mexico, and synthesizes other findings from this region. These research projects analyzed more than 100 excavations in upland and depression sites, cored lakes and wetland sediments, and studied sediments in the field and laboratory using radiocarbon dating, a battery of soil chemistry tests, stratigraphic analysis, magnetic susceptibility, elemental analyses, and artifact identification. Our objective was to date when sedimentation and soil erosion occurred, identify stable surfaces, and correlate them with the state of knowledge about past land use. These findings indicate three general epochs of accelerated soil erosion and identified two major paleosols. The three waves of soil erosion occurred in the Preclassic period (c. 1000 BC to AD 250), the Late Classic (AD 550 to 900), and in the last several decades. The major paleosol (‘Eklu'um’) in these sites is a well-developed Mollisol or Vertisol that started forming in the early Holocene and was buried in either the Preclassic or Classic periods (AD 250 to 900). At some sites the Eklu'um paleosol lies beneath sediments with a fainter paleosol, which in turn lies buried below Classic period and later sediments. This picture shows higher than expected soil erosion linked to the region's first pioneer farmers in the Preclassic and less than expected soil erosion in the Late Classic when population peaked and land use was the most intensive. In other regions like Cancuén, Guatemala, however, most soil erosion occurred during the Maya Late Classic (AD 550–830). Erosion here was intense but short-lived: depressions record 1–3 m of aggradation in two centuries. A third epoch of accelerated soil loss and aggradation arose with the rapid land use changes brought by new pioneers during the last several decades.

CATENA, 2011

This article provides new data and synthesizes earlier findings on the carbon isotope ratios of t... more This article provides new data and synthesizes earlier findings on the carbon isotope ratios of the humin part of soil organic matter from a range of sites in the central Maya Lowlands. Changes down the soil profile in carbon isotope ratios can provide an important line of evidence for vegetation change and erosion over time, especially in well dated aggrading profiles. Research thus far has provided substantial evidence for significant inputs from C 4 vegetation in buried layers from the Ancient Maya periods in depositional soils but equivocal evidence from sloping soils. We present new findings from soil profiles through ancient Maya wetland fields, upland karst wetlands, ancient Maya aguadas (reservoirs), and ancient Maya terraces. Most of the profiles exhibited δ 13 C enrichment greater than the 2.5-3‰ typical from bacterial fractionation. Seven of nine ancient Maya wetland profiles showed δ 13 C enrichment ranging from 4.25 to 8.56‰ in ancient Maya-dated sediments that also contained phytolith and pollen evidence of grass (C 4 species) dominance. Upland karst sinks and ancient reservoirs produced more modest results for δ 13 C enrichment. These seasonal wetland profiles exhibited δ 13 C enrichment ranging from 1 to 7.3‰ from the surface to ancient Maya-period sediments. Agricultural terraces produced mixed results, with two terraces having substantial δ 13 C enrichment of 5.34 and 5.66‰ and two producing only equivocal results of 1.88 and 3.03‰ from modern topsoils to Maya Classicperiod buried soils. Altogether, these findings indicate that C 4 plants made up c. 25% of the vegetation at our sites in the Maya Classic period and only a few percent today. These findings advance the small corpus of studies from ancient terraces, karst sinks, and ancient wetland fields by demonstrating substantial δ 13 C and thus C 4 plant enrichment in soil profile sections dated to ancient Maya times. These studies are also providing a new line of evidence about local and regional soil and ecological change in this region of widespread environmental change in the Late Holocene.

PNAS, 2019

We report on a large area of ancient Maya wetland field systems in Belize, Central America, based... more We report on a large area of ancient Maya wetland field systems
in Belize, Central America, based on airborne lidar survey coupled
with multiple proxies and radiocarbon dates that reveal ancient
field uses and chronology. The lidar survey indicated four main areas
of wetland complexes, including the Birds of Paradise wetland field
complex that is five times larger than earlier remote and ground
survey had indicated, and revealed a previously unknown wetland
field complex that is even larger. The field systems date mainly to
the Maya Late and Terminal Classic (∼1,400–1,000 y ago), but with
evidence from as early as the Late Preclassic (∼1,800 y ago) and as
late as the Early Postclassic (∼900 y ago). Previous study showed
that these were polycultural systems that grew typical ancient
Maya crops including maize, arrowroot, squash, avocado, and other
fruits and harvested fauna. The wetland fields were active at a time
of population expansion, landscape alteration, and droughts and
could have been adaptations to all of these major shifts in Maya
civilization. These wetland-farming systems add to the evidence for
early and extensive human impacts on the global tropics. Broader
evidence suggests a wide distribution of wetland agroecosystems
across the Maya Lowlands and Americas, and we hypothesize the
increase of atmospheric carbon dioxide and methane from burning,
preparing, and maintaining these field systems contributed to the
Early Anthropocene.

Journal of Ethnobiology, 2008

... 2009. Arising from the wetlands: Mechanisms and chronology of landscape aggradation in the no... more ... 2009. Arising from the wetlands: Mechanisms and chronology of landscape aggradation in the northern coastal plain of Belize. ... Pre-Columbian wetland soils investigation, Blue Creek, Belize. ... In Ancient Maya wetland agriculture: Excavations on Albion Island, northern Belize. ...

Geomorphology, 2008

We examined the alluvial history of the plain near Kinet Höyük, an archaeological mound (or Tell)... more We examined the alluvial history of the plain near Kinet Höyük, an archaeological mound (or Tell) with a sequence of six millennia of occupation on the southeast Mediterranean coast of Turkey, through 17 excavations over a 1000 m transect near the Mound. Excavations ranged from 2 to 6 m deep and up to 20 m across. This low gradient, alluvial plain shows significantly different rates and processes of near-Mound sedimentation, with one unit having nearly 4 m of Late Bronze Age habitation and flood deposits and another having 4 m of Hellenistic channel and floodplain deposition. This flat, alluvial surface turns out to be a rich geoarchaeological landscape that shrouds Early and Late Bronze Age settlements, Hellenistic walls, and two epochs of Roman Roads. One widespread phenomenon was a Hellenistic or earlier paleosol and occupation level covered by channel gravels and overbank deposits mostly from the Hellenistic to the Late Roman period. These channel and floodplain deposits filled in and flattened out the off-Mound settlements, blanketing the Pre-Hellenistic topography and silting in a long active port. This glut of alluvium correlates in time with drier conditions and the most intensive land uses in the watershed, where Roman and Hellenistic sites today are severely eroded.

Geomorphology

to the lineage with TAE2 allele coming from southeast Turkey-north Syria, where local Aegilops ta... more to the lineage with TAE2 allele coming from southeast Turkey-north Syria, where local Aegilops tauschii has a high frequency in TAE2 allele. Recent finds from the sites of Aratashen and Aknashen-Khatunarkh suggest that a naked wheat, most probably a hexaploid, was in the process of replacing emmer wheat during the occupation of the sites. These finds support the genetic evidence, which suggests that hexploides wheat evolved independently in this region.

Archaeologists have long tended to conflate political evolutionary stages with Polanyi’s (1957) m... more Archaeologists have long tended to conflate political evolutionary stages with Polanyi’s (1957) modes of exchange: bands and tribes with reciprocity, chiefdoms and early states with redistribution, and more developed states with market exchange. According to this scheme, the Classic lowland Maya (Fig. 1) are relegated to chiefdoms or an early state level of political organization with redistribution as the primary, or at least the most ostensible, mode of exchange: control of all or most labor, production, and the dominant mode(s) of exchange were concentrated in a highly centralized authority figure – a paramount chief or king and/or a polyarchy of elite kin groups – who traded exotic goods among themselves. Elites traded with each other while extracting other goods, most importantly agricultural output, from the majority population through taxes and tribute to maintain themselves and a civic/religious infrastructure they symbolized. Those at the top of the hierarchy then redistributed some of these goods down the social ladder in payment for fealty, loyal service, and the like, often at communal rituals and feasts. These Neoevolutionary concepts – bands, tribes, chiefdoms, and states, and the various forms of reciprocity, redistribution, and market exchange – are heuristic devices, or broadly conceptualized and loosely correlated classificatory forms of social and economic organization, designed to facilitate cross-cultural comparisons and to fill in holes where hard data are lacking. Obviously, they have been highly useful in constructing models. Therefore, the pocket critique of their application to the Maya that follows is not intended to challenge their utility, nor to rewrite Neoevolutionary theory, but rather to emphasize that these concepts have historically tended to narrow our perceptions and made it difficult to identify market exchange as an important facet of Classic Maya economies (see e.g., Yoffee 1977; West 2002; Sharer and Golden 2004; Rice 2008). (Authored by Bruce H. Dahlin, Daniel Bair, Tim Beach, Matthew Moriarty, and Richard Terry).

Science, 2019

Environmentally transformative human use of land accelerated with the emergence of agriculture, b... more Environmentally transformative human use of land accelerated with the emergence of agriculture, but the extent, trajectory, and implications of these early changes are not well understood. An empirical global assessment of land use from 10,000 years before the present (yr B.P.) to 1850 CE reveals a planet largely transformed by hunter-gatherers, farmers, and pastoralists by 3000 years ago, considerably earlier than the dates in the land-use reconstructions commonly used by Earth scientists. Synthesis of knowledge contributed by more than 250 archaeologists highlighted gaps in archaeological expertise and data quality, which peaked for 2000 yr B.P. and in traditionally studied and wealthier regions. Archaeological reconstruction of global land-use history illuminates the deep roots of Earth's transformation and challenges the emerging Anthropocene paradigm that large-scale anthropogenic global environmental change is mostly a recent phenomenon.

Antiquity, 2016

In recent years, a growing body of research has focused on the importance of water management for... more In recent years, a growing body of research
has focused on the importance of water
management for ancient Maya societies, and
more generally on the cultural and economic
significance of water as a resource. But how
did this change across the centuries as cycles
of drought and sea level rise, together with
the growingMaya footprint on the landscape,
presented new challenges? As the resolution
of climatic records improves, the authors can
begin to show in detail how Maya water
management responded and adapted to such
shifts. This included the manipulation of
aguadas and the development of wetland field
systems, in the process transforming large areas
of the Maya landscape.