Human and climate global-scale imprint on sediment transfer during the Holocene.

Accelerated soil erosion has become a pervasive feature on landscapes around the world and is recognized to have substantial implications for land productivity, downstream water quality, and biogeochemical cycles. However, the scarcity of global syntheses that consider long-term processes has limited our understanding of the timing, the amplitude, and the extent of soil erosion over millennial time scales. As such, we lack the ability to make predictions about the responses of soil erosion to long-term climate and land cover changes. Here, we reconstruct sedimentation rates for 632 lakes based on chronologies constrained by 3,980 calibrated 14C ages to assess the relative changes in lake-watershed erosion rates over the last 12,000 y. Estimated soil erosion dynamics were then complemented with land cover reconstructions inferred from 43,669 pollen samples and with climate time series from the Max Planck Institute Earth System Model. Our results show that a significant portion of the Earth surface shifted to human-driven soil erosion rate already 4,000 y ago. In particular, inferred soil erosion rates increased in 35% of the watersheds, and most of these sites showed a decrease in the proportion of arboreal pollen, which would be expected with land clearance. Further analysis revealed that land cover change was the main driver of inferred soil erosion in 70% of all studied watersheds. This study suggests that soil erosion has been altering terrestrial and aquatic ecosystems for millennia, leading to carbon (C) losses that could have ultimately induced feedbacks on the climate system.

"Organismic" positions in early German-speaking ecology and its (almost) forgotten dissidents.

In early German ecology, the key concept used to refer to a synecological unit was Biozönose (biocoenosis). Taken together with the concept of the Biotop (biotope), it was also understood as an integrated higher-order unit of life, sometimes called a "Holozön" (holocoen). These units were often perceived as having properties similar to those of individual organisms, and they informed the mainstream of German ecology until at least the late 1960s. Here I ask how "organismic" these concepts really were and what conceptual problems they entailed. To do so, I focus on some almost forgotten dissident positions, especially those of (German-born) Friedrich Simon Bodenheimer and Fritz Peus, which I contrast with the mainstream German ecology of the time. In a radical paper published in 1954 that postulated the "dissolution of the concepts of biocoenosis and biotope", Peus in particular elicited a forceful response from many prominent German ecologists. An analysis of the ensuing debate, including especially a colloquium held in 1959 that was partly inspired by Peus' paper, is helpful for sifting the various arguments proffered with respect to a quasi-organismic perception of the biocoenosis in German speaking ecology. Although German mainstream ecologists rejected the notion of the biocoenosis as a superorganism, ontological holism was quite common among them. Additionally, the mainstream concept of the biocoenosis was plagued by several methodological problems and much conceptual confusion, to which the "dissidents" rightly pointed. Some of these problems are still pertinent today, e.g. in connection with more modern concepts such as "ecosystem".

Neither superorganisms nor mere species aggregates: Charles Elton's sociological analogies and his moderate holism about ecological communities.

This paper analyzes community ecologist Charles Elton's ideas on animal communities, and situates them with respect to the classical opposition between organicist-holistic and individualistic-reductionist ecological views drawn by many historians of ecology. It is argued that Elton espoused a moderate ecological holism, which drew a middle way between the stricter ecological holism advocated by organicist ecologists and the merely aggregationist views advocated by some of their opponents. It is also argued that Elton's moderate ecological holism resonated with his preference for analogies between ecological communities and human societies over more common ones between communities and individual organisms. I discuss, on the one hand, how the functionalist-interactionist approach to community ecology introduced by Elton entailed a view of ecological communities as more or less self-maintaining functionally organized wholes, and how his ideas on this matter were incorporated into their views by organicist ecologists Frederic Clements, Victor Shelford, and Warder C. Allee et al. On the other hand, I identify some important divergences between Elton's ecological ideas and those of organicist ecologists. Specifically, I show (1) how Elton's ideas on species distribution, animal migrations, and ecological succession entailed a view of animal communities as exhibiting a weaker degree of part-whole integration than that attributed to them by Clements and Shelford; and (2) how Elton's mixed stance on the balance of nature idea and his associated views on community stability attributed to communities a weaker form of self-regulation than that attributed to them by Allee et al.

How the Modern Synthesis Came to Ecology.

Ecology in principle is tied to evolution, since communities and ecosystems result from evolution and ecological conditions determine fitness values (and ultimately evolution by natural selection). Yet the two disciplines of evolution and ecology were not unified in the twentieth-century. The architects of the Modern Synthesis, and especially Julian Huxley, constantly pushed for such integration, but the major ideas of the Synthesis-namely, the privileged role of selection and the key role of gene frequencies in evolution-did not directly or immediately translate into ecological science. In this paper I consider five stages through which the Synthesis was integrated into ecology and distinguish between various ways in which a possible integration was gained. I start with Elton's animal ecology (1927), then consider successively Ford's ecological genetics in the 1940s, the major textbook Principles of animal ecology edited by Allee et al. (1949), and the debates over the role of competition in population regulation in the 1950s, ending with Hutchinson's niche concept (1959) and McArthur and Wilson's Principles of Island Biogeography (1967) viewed as a formal transposition of Modern Synthesis explanatory schemes. I will emphasize the key role of founders of the Synthesis at each stage of this very nonlinear history.

Fifty Years of Mountain Passes: A Perspective on Dan Janzen's Classic Article.

In 1967, Dan Janzen published "Why Mountain Passes Are Higher in the Tropics" in The American Naturalist. Janzen's seminal article has captured the attention of generations of biologists and continues to inspire theoretical and empirical work. The underlying assumptions and derived predictions are broadly synthetic and widely applicable. Consequently, Janzen's "seasonality hypothesis" has proven relevant to physiology, climate change, ecology, and evolution. To celebrate the fiftieth anniversary of this highly influential article, we highlight the past, present, and future of this work and include a unique historical perspective from Janzen himself.

Moderate climate signature in cranial anatomy of late holocene human populations from Southern South America.

OBJECTIVE: The aim of this study is to analyze the association between cranial variation and climate in order to discuss their role during the diversification of southern South American populations. Therefore, the specific objectives are: (1) to explore the spatial pattern of cranial variation with regard to the climatic diversity of the region, and (2) to evaluate the differential impact that the climatic factors may have had on the shape and size of the diverse cranial structures studied. MATERIALS AND METHODS: The variation in shape and size of 361 crania was studied, registering 62 3D landmarks that capture shape and size variation in the face, cranial vault, and base. Mean, minimum, and maximum annual temperature, as well as mean annual precipitation, but also diet and altitude, were matched for each population sample. A PCA, as well as spatial statistical techniques, including kriging, regression, and multimodel inference were employed. RESULTS: The facial skeleton size presents a latitudinal pattern which is partially associated with temperature diversity. Both diet and altitude are the variables that mainly explain the skull shape variation, although mean annual temperature also plays a role. The association between climate factors and cranial variation is low to moderate, mean annual temperature explains almost 40% of the entire skull, facial skeleton and cranial vault shape variation, while annual precipitation and minimum annual temperature only contribute to the morphological variation when considered together with maximum annual temperature. The cranial base is the structure less associated with climate diversity. CONCLUSION: These results suggest that climate factors may have had a partial impact on the facial and vault shape, and therefore contributed moderately to the diversification of southern South American populations, while diet and altitude might have had a stronger impact. Therefore, cranial variation at the southern cone has been shaped both by random and nonrandom factors. Particularly, the influence of climate on skull shape has probably been the result of directional selection. This study supports that, although cranial vault is the cranial structure more associated to mean annual temperature, the impact of climate signature on morphology decreases when populations from extreme cold environments are excluded from the analysis. Additionally, it shows that the extent of the geographical scales analyzed, as well as differential sampling may lead to different results regarding the role of ecological factors and evolutionary processes on cranial morphology.

Ecological and cultural shifts of hunter-gatherers of the Jomon period paralleled with environmental changes.

OBJECTIVES: Holocene hunter-gatherers adapted to climatic and environmental changes over time. Carbon and nitrogen stable isotope analysis of human skeletal remains from the Inariyama shell mound of the Final Jomon period have revealed large dietary variations in the population. This study analyzed radiocarbon dates of these individuals to test temporal changes in diet and its relationship with tooth ablation. MATERIALS AND METHODS: Twenty-nine human skeletal remains from Inariyama were included in this study. Extracted bone collagen samples were purified to graphite. Then, radiocarbon dating of these samples was performed using the accelerator mass spectrometer. RESULTS: The radiocarbon ages of Inariyama ranged about, 3,230-2,140 cal BP and showed three peaks of occupation. In the early and late phases, terrestrial resource consumption and incisor extraction were observed, while marine resource consumption and canine extraction were observed in the middle phase. DISCUSSION: These temporal changes of diet and tooth ablation types occurred in parallel with climatic cooling and environmental change and help reveal how Holocene hunter-gatherers adapted to the changing environments.

The Development of Sociobiology in Relation to Animal Behavior Studies, 1946-1975.

This paper aims at bridging a gap between the history of American animal behavior studies and the history of sociobiology. In the post-war period, ecology, comparative psychology and ethology were all investigating animal societies, using different approaches ranging from fieldwork to laboratory studies. We argue that this disunity in "practices of place" (Kohler, Robert E. Landscapes & Labscapes: Exploring the Lab-Field Border in Biology. Chicago: University of Chicago Press, 2002) explains the attempts of dialogue between those three fields and early calls for unity through "sociobiology" by J. Paul Scott. In turn, tensions between the naturalist tradition and the rising reductionist approach in biology provide an original background for a history of Edward Wilson's own version of sociobiology, much beyond the William Hamilton's papers (Journal of Theoretical Biology 7: 1-16, 17-52, 1964) usually considered as its key antecedent. Naturalists were in a defensive position in the geography of the fields studying animal behavior, and in reaction were a driving force behind the various projects of synthesis called "sociobiology".

Africanizing Science in Post-colonial Kenya: Long-Term Field Research in the Amboseli Ecosystem, 1963-1989.

Following Kenya's independence in 1963, scientists converged on an ecologically sensitive area in southern Kenya on the northern slope of Mt. Kilimanjaro called Amboseli. This region is the homeland of the Ilkisongo Maasai who grazed this ecosystem along with the wildlife of interest to the scientists. Biologists saw opportunities to study this complex community, an environment rich in biological diversity. The Amboseli landscape proved to be fertile ground for testing new methods and lines of inquiry in the biological sciences that were generalizable and important for shaping natural resource management policies in Kenya. However, the local community was in the midst of its own transformation from a primarily transhumant lifestyle to a largely sedentary one, a complex political situation between local and national authorities, and the introduction of a newly educated generation. This article examines the intersection of African history and field science through the post-colonial Africanization of Kenyan politics, the broadening of scientific practices in Amboseli in previously Western-occupied spaces to include Kenyan participants, and an increasing awareness of the role of local African contexts in the results, methods, and implications of biological research. "Africanization" as an idea in the history of science is multifaceted encompassing not just Africans in the scientific process, but it needs an examination of the larger political and social context on both a local and national level.

Historical foundations and future directions in macrosystems ecology.

Macrosystems ecology is an effort to understand ecological processes and interactions at the broadest spatial scales and has potential to help solve globally important social and ecological challenges. It is important to understand the intellectual legacies underpinning macrosystems ecology: How the subdiscipline fits within, builds upon, differs from and extends previous theories. We trace the rise of macrosystems ecology with respect to preceding theories and present a new hypothesis that integrates the multiple components of macrosystems theory. The spatio-temporal anthropogenic rescaling (STAR) hypothesis suggests that human activities are altering the scales of ecological processes, resulting in interactions at novel space-time scale combinations that are diverse and predictable. We articulate four predictions about how human actions are "expanding", "shrinking", "speeding up" and "slowing down" ecological processes and interactions, and thereby generating new scaling relationships for ecological patterns and processes. We provide examples of these rescaling processes and describe ecological consequences across terrestrial, freshwater and marine ecosystems. Rescaling depends in part on characteristics including connectivity, stability and heterogeneity. Our STAR hypothesis challenges traditional assumptions about how the spatial and temporal scales of processes and interactions operate in different types of ecosystems and provides a lens through which to understand macrosystem-scale environmental change.

The "balance of nature"-evolution of a Panchreston.

The earliest concept of a balance of nature in Western thought saw it as being provided by gods but requiring human aid or encouragement for its maintenance. With the rise of Greek natural philosophy, emphasis shifted to traits gods endowed species with at the outset, rather than human actions, as key to maintaining the balance. The dominance of a constantly intervening God in the Middle Ages lessened interest in the inherent features of nature that would contribute to balance, but the Reformation led to renewed focus on such features, particularly traits of species that would maintain all of them but permit none to dominate nature. Darwin conceived of nature in balance, and his emphasis on competition and frequent tales of felicitous species interactions supported the idea of a balance of nature. But Darwin radically changed its underlying basis, from God to natural selection. Wallace was perhaps the first to challenge the very notion of a balance of nature as an undefined entity whose accuracy could not be tested. His skepticism was taken up again in the 20th century, culminating in a widespread rejection of the idea of a balance of nature by academic ecologists, who focus rather on a dynamic, often chaotic nature buffeted by constant disturbances. The balance-of-nature metaphor, however, lives on in large segments of the public, representing a fragile aspect of nature and biodiversity that it is our duty to protect.