Publications by authors named "Timothy A Kohler"

17 Publications

  • Page 1 of 1

Loss of resilience preceded transformations of pre-Hispanic Pueblo societies.

Proc Natl Acad Sci U S A 2021 05;118(18)

Department of Anthropology, Washington State University, Pullman, WA 99164-4910;

Climate extremes are thought to have triggered large-scale transformations of various ancient societies, but they rarely seem to be the sole cause. It has been hypothesized that slow internal developments often made societies less resilient over time, setting them up for collapse. Here, we provide quantitative evidence for this idea. We use annual-resolution time series of building activity to demonstrate that repeated dramatic transformations of Pueblo cultures in the pre-Hispanic US Southwest were preceded by signals of critical slowing down, a dynamic hallmark of fragility. Declining stability of the status quo is consistent with archaeological evidence for increasing violence and in some cases, increasing wealth inequality toward the end of these periods. Our work thus supports the view that the cumulative impact of gradual processes may make societies more vulnerable through time, elevating the likelihood that a perturbation will trigger a large-scale transformation that includes radically rejecting the status quo and seeking alternative pathways.
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http://dx.doi.org/10.1073/pnas.2024397118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8106319PMC
May 2021

How can evolutionary and biological anthropologists engage broader audiences?

Am J Hum Biol 2021 07 9;33(4):e23592. Epub 2021 Mar 9.

Department of Integrative Biology, Oklahoma State University, Stillwater, Oklahoma, USA.

Objectives: With our diverse training, theoretical and empirical toolkits, and rich data, evolutionary and biological anthropologists (EBAs) have much to contribute to research and policy decisions about climate change and other pressing social issues. However, we remain largely absent from these critical, ongoing efforts. Here, we draw on the literature and our own experiences to make recommendations for how EBAs can engage broader audiences, including the communities with whom we collaborate, a more diverse population of students, researchers in other disciplines and the development sector, policymakers, and the general public. These recommendations include: (1) playing to our strength in longitudinal, place-based research, (2) collaborating more broadly, (3) engaging in greater public communication of science, (4) aligning our work with open-science practices to the extent possible, and (5) increasing diversity of our field and teams through intentional action, outreach, training, and mentorship.

Conclusions: We EBAs need to put ourselves out there: research and engagement are complementary, not opposed to each other. With the resources and workable examples we provide here, we hope to spur more EBAs to action.
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http://dx.doi.org/10.1002/ajhb.23592DOI Listing
July 2021

Survival of the Systems.

Trends Ecol Evol 2021 04 4;36(4):333-344. Epub 2021 Jan 4.

Aquatic Ecology and Water Quality Management, Wageningen University, 6700AA Wageningen, The Netherlands.

Since Darwin, individuals and more recently genes, have been the focus of evolutionary thinking. The idea that selection operates on nonreproducing, higher-level systems including ecosystems or societies, has met with scepticism. But research emphasising that natural selection can be based solely on differential persistence invites reconsideration of their evolution. Self-perpetuating feedback cycles involving biotic as well as abiotic components are critical to determining persistence. Evolution of autocatalytic networks of molecules is well studied, but the principles hold for any 'self-perpetuating' system. Ecosystem examples include coral reefs, rainforests, and savannahs. Societal examples include agricultural systems, dominant belief systems, and economies. Persistence-based selection of feedbacks can help us understand how ecological and societal systems survive or fail in a changing world.
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http://dx.doi.org/10.1016/j.tree.2020.12.003DOI Listing
April 2021

Scale and information-processing thresholds in Holocene social evolution.

Nat Commun 2020 05 14;11(1):2394. Epub 2020 May 14.

Santa Fe Institute, 1399 Hyde Park Rd, Santa Fe, NM, 87501, USA.

Throughout the Holocene, societies developed additional layers of administration and more information-rich instruments for managing and recording transactions and events as they grew in population and territory. Yet, while such increases seem inevitable, they are not. Here we use the Seshat database to investigate the development of hundreds of polities, from multiple continents, over thousands of years. We find that sociopolitical development is dominated first by growth in polity scale, then by improvements in information processing and economic systems, and then by further increases in scale. We thus define a Scale Threshold for societies, beyond which growth in information processing becomes paramount, and an Information Threshold, which once crossed facilitates additional growth in scale. Polities diverge in socio-political features below the Information Threshold, but reconverge beyond it. We suggest an explanation for the evolutionary divergence between Old and New World polities based on phased growth in scale and information processing. We also suggest a mechanism to help explain social collapses with no evident external causes.
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http://dx.doi.org/10.1038/s41467-020-16035-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7224170PMC
May 2020

Future of the human climate niche.

Proc Natl Acad Sci U S A 2020 05 4;117(21):11350-11355. Epub 2020 May 4.

Santa Fe Institute, Santa Fe, NM 87501;

All species have an environmental niche, and despite technological advances, humans are unlikely to be an exception. Here, we demonstrate that for millennia, human populations have resided in the same narrow part of the climatic envelope available on the globe, characterized by a major mode around ∼11 °C to 15 °C mean annual temperature (MAT). Supporting the fundamental nature of this temperature niche, current production of crops and livestock is largely limited to the same conditions, and the same optimum has been found for agricultural and nonagricultural economic output of countries through analyses of year-to-year variation. We show that in a business-as-usual climate change scenario, the geographical position of this temperature niche is projected to shift more over the coming 50 y than it has moved since 6000 BP. Populations will not simply track the shifting climate, as adaptation in situ may address some of the challenges, and many other factors affect decisions to migrate. Nevertheless, in the absence of migration, one third of the global population is projected to experience a MAT >29 °C currently found in only 0.8% of the Earth's land surface, mostly concentrated in the Sahara. As the potentially most affected regions are among the poorest in the world, where adaptive capacity is low, enhancing human development in those areas should be a priority alongside climate mitigation.
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http://dx.doi.org/10.1073/pnas.1910114117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7260949PMC
May 2020

Greater post-Neolithic wealth disparities in Eurasia than in North America and Mesoamerica.

Nature 2017 11 15;551(7682):619-622. Epub 2017 Nov 15.

Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501, USA.

How wealth is distributed among households provides insight into the fundamental characters of societies and the opportunities they afford for social mobility. However, economic inequality has been hard to study in ancient societies for which we do not have written records, which adds to the challenge of placing current wealth disparities into a long-term perspective. Although various archaeological proxies for wealth, such as burial goods or exotic or expensive-to-manufacture goods in household assemblages, have been proposed, the first is not clearly connected with households, and the second is confounded by abandonment mode and other factors. As a result, numerous questions remain concerning the growth of wealth disparities, including their connection to the development of domesticated plants and animals and to increases in sociopolitical scale. Here we show that wealth disparities generally increased with the domestication of plants and animals and with increased sociopolitical scale, using Gini coefficients computed over the single consistent proxy of house-size distributions. However, unexpected differences in the responses of societies to these factors in North America and Mesoamerica, and in Eurasia, became evident after the end of the Neolithic period. We argue that the generally higher wealth disparities identified in post-Neolithic Eurasia were initially due to the greater availability of large mammals that could be domesticated, because they allowed more profitable agricultural extensification, and also eventually led to the development of a mounted warrior elite able to expand polities (political units that cohere via identity, ability to mobilize resources, or governance) to sizes that were not possible in North America and Mesoamerica before the arrival of Europeans. We anticipate that this analysis will stimulate other work to enlarge this sample to include societies in South America, Africa, South Asia and Oceania that were under-sampled or not included in this study.
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http://dx.doi.org/10.1038/nature24646DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5714260PMC
November 2017

Prehistoric mitochondrial DNA of domesticate animals supports a 13th century exodus from the northern US southwest.

PLoS One 2017 26;12(7):e0178882. Epub 2017 Jul 26.

Department of Anthropology, Washington State University, Pullman, Washington, United States of America.

The 13th century Puebloan depopulation of the Four Corners region of the US Southwest is an iconic episode in world prehistory. Studies of its causes, as well as its consequences, have a bearing not only on archaeological method and theory, but also social responses to climate change, the sociology of social movements, and contemporary patterns of cultural diversity. Previous research has debated the demographic scale, destinations, and impacts of Four Corners migrants. Much of this uncertainty stems from the substantial differences in material culture between the Four Corners vs. hypothesized destination areas. Comparable biological evidence has been difficult to obtain due to the complete departure of farmers from the Four Corners in the 13th century CE and restrictions on sampling human remains. As an alternative, patterns of genetic variation among domesticated species were used to address the role of migration in this collapse. We collected mitochondrial haplotypic data from dog (Canis lupus familiaris) and turkey (Meleagris gallopavo) remains from archaeological sites in the most densely-populated portion of the Four Corners region, and the most commonly proposed destination area for that population under migration scenarios. Results are consistent with a large-scale migration of humans, accompanied by their domestic turkeys, during the 13th century CE. These results support scenarios that suggest contemporary Pueblo peoples of the Northern Rio Grande are biological and cultural descendants of Four Corners populations.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0178882PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5528258PMC
October 2017

Twenty-first century approaches to ancient problems: Climate and society.

Proc Natl Acad Sci U S A 2016 12 12;113(51):14483-14491. Epub 2016 Dec 12.

Department of Anthropology, Washington State University, Pullman, WA 99163.

By documenting how humans adapted to changes in their environment that are often much greater than those experienced in the instrumental record, archaeology provides our only deep-time laboratory for highlighting the circumstances under which humans managed or failed to find to adaptive solutions to changing climate, not just over a few generations but over the longue durée Patterning between climate-mediated environmental change and change in human societies has, however, been murky because of low spatial and temporal resolution in available datasets, and because of failure to model the effects of climate change on local resources important to human societies. In this paper we review recent advances in computational modeling that, in conjunction with improving data, address these limitations. These advances include network analysis, niche and species distribution modeling, and agent-based modeling. These studies demonstrate the utility of deep-time modeling for calibrating our understanding of how climate is influencing societies today and may in the future.
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http://dx.doi.org/10.1073/pnas.1616188113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5187725PMC
December 2016

Exploration and exploitation in the macrohistory of the pre-Hispanic Pueblo Southwest.

Sci Adv 2016 Apr 1;2(4):e1501532. Epub 2016 Apr 1.

Department of Anthropology, Washington State University, Pullman, WA 99164-4910, USA.; Crow Canyon Archaeological Center, Cortez, CO 81321, USA.; Santa Fe Institute, Santa Fe, NM 87501, USA.

Cycles of demographic and organizational change are well documented in Neolithic societies, but the social and ecological processes underlying them are debated. Such periodicities are implicit in the "Pecos classification," a chronology for the pre-Hispanic U.S. Southwest introduced in Science in 1927 which is still widely used. To understand these periodicities, we analyzed 29,311 archaeological tree-ring dates from A.D. 500 to 1400 in the context of a novel high spatial resolution, annual reconstruction of the maize dry-farming niche for this same period. We argue that each of the Pecos periods initially incorporates an "exploration" phase, followed by a phase of "exploitation" of niches that are simultaneously ecological, cultural, and organizational. Exploitation phases characterized by demographic expansion and aggregation ended with climatically driven downturns in agricultural favorability, undermining important bases for social consensus. Exploration phases were times of socio-ecological niche discovery and development.
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http://dx.doi.org/10.1126/sciadv.1501532DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4820384PMC
April 2016

THE SOCIAL CONSEQUENCES OF CLIMATE CHANGE IN THE CENTRAL MESA VERDE REGION.

Am Antiq 2016 Jan;81(1):74-96

Department of Anthropology, Washington State University, Pullman, WA 99164-4910, Santa Fe Institute, and Crow Canyon Archaeological Center.

The consequences of climate change vary over space and time. Effective studies of human responses to climatically induced environmental change must therefore sample the environmental diversity experienced by specific societies. We reconstruct population histories from A.D. 600 to 1280 in six environmentally distinct portions of the central Mesa Verde region in southwestern Colorado, relating these to climate-driven changes in agricultural potential. In all but one subregion, increases in maize-niche size led to increases in population size. Maize-niche size is also positively correlated with regional estimates of birth rates. High birth rates continued to accompany high population levels even as productive conditions declined in the A.D. 1200s. We reconstruct prominent imbalances between the maize-niche size and population densities in two subregions from A.D. 1140 to 1180 and from A.D. 1225-1260. We propose that human responses in those subregions, beginning by the mid-A.D. 1200s, contributed to violence and social collapse across the entire society. Our findings are relevant to discussions of how climate change will affect contemporary societies.
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http://dx.doi.org/10.7183/0002-7316.81.1.74DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7523884PMC
January 2016

DNA analysis of ancient dogs of the Americas: identifying possible founding haplotypes and reconstructing population histories.

J Hum Evol 2015 Feb 18;79:105-18. Epub 2014 Dec 18.

School of Integrative Biology, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA; Department of Anthropology and Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA. Electronic address:

As dogs have traveled with humans to every continent, they can potentially serve as an excellent proxy when studying human migration history. Past genetic studies into the origins of Native American dogs have used portions of the hypervariable region (HVR) of mitochondrial DNA (mtDNA) to indicate that prior to European contact the dogs of Native Americans originated in Eurasia. In this study, we summarize past DNA studies of both humans and dogs to discuss their population histories in the Americas. We then sequenced a portion of the mtDNA HVR of 42 pre-Columbian dogs from three sites located in Illinois, coastal British Columbia, and Colorado, and identify four novel dog mtDNA haplotypes. Next, we analyzed a dataset comprised of all available ancient dog sequences from the Americas to infer the pre-Columbian population history of dogs in the Americas. Interestingly, we found low levels of genetic diversity for some populations consistent with the possibility of deliberate breeding practices. Furthermore, we identified multiple putative founding haplotypes in addition to dog haplotypes that closely resemble those of wolves, suggesting admixture with North American wolves or perhaps a second domestication of canids in the Americas. Notably, initial effective population size estimates suggest at least 1000 female dogs likely existed in the Americas at the time of the first known canid burial, and that population size increased gradually over time before stabilizing roughly 1200 years before present.
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http://dx.doi.org/10.1016/j.jhevol.2014.10.012DOI Listing
February 2015

A 2,000-year reconstruction of the rain-fed maize agricultural niche in the US Southwest.

Nat Commun 2014 Dec 4;5:5618. Epub 2014 Dec 4.

1] Department of Anthropology, Washington State University, Pullman, Washington 99164, USA [2] Santa Fe Institute, Santa Fe, New Mexico 87501, USA [3] Crow Canyon Archaeological Center, Cortez, Colorado 81321, USA.

Humans experience, adapt to and influence climate at local scales. Paleoclimate research, however, tends to focus on continental, hemispheric or global scales, making it difficult for archaeologists and paleoecologists to study local effects. Here we introduce a method for high-frequency, local climate-field reconstruction from tree-rings. We reconstruct the rain-fed maize agricultural niche in two regions of the southwestern United States with dense populations of prehispanic farmers. Niche size and stability are highly variable within and between the regions. Prehispanic rain-fed maize farmers tended to live in agricultural refugia--areas most reliably in the niche. The timing and trajectory of the famous thirteenth century Pueblo migration can be understood in terms of relative niche size and stability. Local reconstructions like these illuminate the spectrum of strategies past humans used to adapt to climate change by recasting climate into the distributions of resources on which they depended.
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http://dx.doi.org/10.1038/ncomms6618DOI Listing
December 2014

Long and spatially variable Neolithic Demographic Transition in the North American Southwest.

Proc Natl Acad Sci U S A 2014 Jul 30;111(28):10101-6. Epub 2014 Jun 30.

Department of Anthropology, Washington State University, Pullman, WA 99164-4910;

In many places of the world, a Neolithic Demographic Transition (NDT) is visible as a several-hundred-year period of increased birth rates coupled with stable mortality rates, resulting in dramatic population growth that is eventually curtailed by increased mortality. Similar processes can be reconstructed in particular detail for the North American Southwest, revealing an anomalously long and spatially variable NDT. Irrigation-dependent societies experienced relatively low birth rates but were quick to achieve a high degree of sociopolitical complexity, whereas societies dependent on dry or rainfed farming experienced higher birth rates but less initial sociopolitical complexity. Low birth rates after A.D. 1200 mark the beginning of the decline of the Hohokam. Overall in the Southwest, birth rates increased slowly from 1100 B.C. to A.D. 500, and remained at high levels with some fluctuation until decreasing rapidly beginning A.D. 1300. Life expectancy at 15 increased slowly from 900 B.C. to A.D. 700, and then increased rapidly for 200 y before fluctuating and then declining after A.D. 1400. Life expectancy at birth, on the other hand, generally declined from 1100 B.C. to A.D. 1100/1200, before rebounding. Farmers took two millennia (∼ 1100 B.C. to ∼ A.D. 1000) to reach the carrying capacity of the agricultural niche in the Southwest.
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http://dx.doi.org/10.1073/pnas.1404367111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4104847PMC
July 2014

Simulating ancient societies.

Sci Am 2005 Jul;293(1):76-82, 84

Department of Anthropology, Washington State University, USA.

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http://dx.doi.org/10.1038/scientificamerican0705-76DOI Listing
July 2005
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