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1. Tracing demographic histories through time using ancient DNA in Chilean Fuego-Patagonia

   Balentine, C. M. ; Alfonso-Durruty, M. ; Reynolds, A. W. ; Vilar, M. ; Morello, F. ; San Román, M. ; Springs, L. C. ; Bolnick, D. A. ( January 2022 , American Journal of Biological Anthropology)

   Historically, hunter-gatherers living east and west of the Andean foothills of southern South America (Fuego-Patagonia) practiced different subsistence strategies. To the east, the wide open and relatively dry pampas presented a climate ideal for Terrestrial hunter-gatherers who depended on terrestrial animals (e.g., Lama guanicoe). In contrast, Marine hunter-gatherers who lived on islands in the western archipelago, a colder and wetter environment, mainly subsisted on marine resources (e.g., seals and shellfish). Archaeological evidence dates Terrestrial hunter-gatherers’ presence in Fuego-Patagonia to at least ~10,500 BP, whereas Marine hunter-gatherers’ presence dates to ~6,500 BP and is associated with highly specialized tools that have only been observed in the archaeological record after this time. Genetic analyses of some ancient Fuegian-Patagonians have supported the hypothesis that Marine hunter-gatherers migrated into the region after Terrestrial hunter-gatherers, around 6,500 BP (7,500 calBP), while analyses of other individuals suggest that Marine hunter-gatherers descended from the earlier Terrestrial hunter-gatherer groups. Here, we test these hypotheses by analyzing newly collected genome-wide data from n=46 ancient Chilean Fuegian-Patagonian individuals belonging to Marine, Terrestrial, and Mixed-economy archaeological sites dating to 6,895–304 calBP. We explored basic population structure among these hunter-gatherer groups using PCA and ADMIXTURE. We calculated π, pairwise-FST, and f-statistics, andmore »developed demographic simulations to further examine genetic relationships among the groups. The results of this study shed light on local demographic patterns of ancient southern South American groups, which in turn provides more insight into broader population histories of South America. This study was funded by FONDECYT (Chile), National Geographic Society, National Science Foundation, and Wenner-Gren Foundation. C. M. Balentine is supported by an NSF Graduate Research Fellowship.« less
2. Coastal occupation and foraging during the last glacial maximum and early Holocene at Waterfall Bluff, eastern Pondoland, South Africa

   https://doi.org/10.1017/qua.2020.26  

   Fisher, Erich C. ; Cawthra, Hayley C. ; Esteban, Irene ; Jerardino, Antonieta ; Neumann, Frank H. ; Oertle, Annette ; Pargeter, Justin ; Saktura, Rosaria B. ; Szabó, Katherine ; Winkler, Stephan ; et al ( September 2020 , Quaternary Research)

   Abstract Waterfall Bluff is a rock shelter in eastern Pondoland, South Africa, adjacent to a narrow continental shelf that limited coastline movements across glacial/interglacial cycles. The archaeological deposits are characterized by well-preserved stratigraphy, faunal, and botanical remains alongside abundant stone artifacts and other materials. A comprehensive dating protocol consisting of 5 optically stimulated luminescence ages and 51 accelerator mass spectrometry 14 C ages shows that the record of hunter-gatherer occupations at Waterfall Bluff persisted from the late Pleistocene to the Holocene, spanning the last glacial maximum and the transition from the Pleistocene to the Holocene. Here, we provide detailed descriptions about the sedimentary sequence, chronology, and characteristics of the archaeological deposits at Waterfall Bluff. Remains of marine mollusks and marine fish also show, for the first time, that coastal foraging was a component of some hunter-gatherer groups’ subsistence practices during glacial phases in the late Pleistocene. The presence of marine fish and shellfish further demonstrates that hunter-gatherers selectively targeted coastal resources from intertidal and estuarine habitats. Our results therefore underscore the idea that Pondoland's coastline remained a stable and predictable point on the landscape over the last glacial/interglacial transition being well positioned for hunter-gatherers to access resources from the nearbymore »coastline, narrow continental shelf, and inland areas.« less
3. Sitting, squatting, and the evolutionary biology of human inactivity

   https://doi.org/10.1073/pnas.1911868117  

   Raichlen, David A. ; Pontzer, Herman ; Zderic, Theodore W. ; Harris, Jacob A. ; Mabulla, Audax Z. P. ; Hamilton, Marc T. ; Wood, Brian M. ( March 2020 , Proceedings of the National Academy of Sciences)

   Recent work suggests human physiology is not well adapted to prolonged periods of inactivity, with time spent sitting increasing cardiovascular disease and mortality risk. Health risks from sitting are generally linked with reduced levels of muscle contractions in chair-sitting postures and associated reductions in muscle metabolism. These inactivity-associated health risks are somewhat paradoxical, since evolutionary pressures tend to favor energy-minimizing strategies, including rest. Here, we examined inactivity in a hunter-gatherer population (the Hadza of Tanzania) to understand how sedentary behaviors occur in a nonindustrial economic context more typical of humans’ evolutionary history. We tested the hypothesis that nonambulatory rest in hunter-gatherers involves increased muscle activity that is different from chair-sitting sedentary postures used in industrialized populations. Using a combination of objectively measured inactivity from thigh-worn accelerometers, observational data, and electromygraphic data, we show that hunter-gatherers have high levels of total nonambulatory time (mean ± SD = 9.90 ± 2.36 h/d), similar to those found in industrialized populations. However, nonambulatory time in Hadza adults often occurs in postures like squatting, and we show that these “active rest” postures require higher levels of lower limb muscle activity than chair sitting. Based on our results, we introduce the Inactivity Mismatch Hypothesis and proposemore »that human physiology is likely adapted to more consistently active muscles derived from both physical activity and from nonambulatory postures with higher levels of muscle contraction. Interventions built on this model may help reduce the negative health impacts of inactivity in industrialized populations.

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4. Sexual selection and the ascent of women: Mate choice research since Darwin

   https://doi.org/10.1126/science.abi6308  

   Rosenthal, Gil G. ; Ryan, Michael J. ( January 2022 , Science)

   BACKGROUND Charles Darwin’s  Descent of Man, and Selection in Relation to Sex  tackled the two main controversies arising from the Origin of Species:  the evolution of humans from animal ancestors and the evolution of sexual ornaments. Most of the book focuses on the latter, Darwin’s theory of sexual selection. Research since supports his conjecture that songs, perfumes, and intricate dances evolve because they help secure mating partners. Evidence is overwhelming for a primary role of both male and female mate choice in sexual selection—not only through premating courtship but also through intimate interactions during and long after mating. But what makes one prospective mate more enticing than another? Darwin, shaped by misogyny and sexual prudery, invoked a “taste for the beautiful” without speculating on the origin of the “taste.” How to explain when the “final marriage ceremony” is between two rams? What of oral sex in bats, cloacal rubbing in bonobos, or the sexual spectrum in humans, all observable in Darwin’s time? By explaining desire through the lens of those male traits that caught his eyes and those of his gender and culture, Darwin elided these data in his theory of sexual evolution. Work since Darwin has focused on howmore »traits and preferences coevolve. Preferences can evolve even if attractive signals only predict offspring attractiveness, but most attention has gone to the intuitive but tenuous premise that mating with gorgeous partners yields vigorous offspring. By focusing on those aspects of mating preferences that coevolve with male traits, many of Darwin’s influential followers have followed the same narrow path. The sexual selection debate in the 1980s was framed as “good genes versus runaway”: Do preferences coevolve with traits because traits predict genetic benefits, or simply because they are beautiful? To the broader world this is still the conversation. ADVANCES Even as they evolve toward ever-more-beautiful signals and healthier offspring, mate-choice mechanisms and courter traits are locked in an arms race of coercion and resistance, persuasion and skepticism. Traits favored by sexual selection often do so at the expense of chooser fitness, creating sexual conflict. Choosers then evolve preferences in response to the costs imposed by courters. Often, though, the current traits of courters tell us little about how preferences arise. Sensory systems are often tuned to nonsexual cues like food, favoring mating signals resembling those cues. And preferences can emerge simply from selection on choosing conspecifics. Sexual selection can therefore arise from chooser biases that have nothing to do with ornaments. Choice may occur before mating, as Darwin emphasized, but individuals mate multiple times and bias fertilization and offspring care toward favored partners. Mate choice can thus occur in myriad ways after mating, through behavioral, morphological, and physiological mechanisms. Like other biological traits, mating preferences vary among individuals and species along multiple dimensions. Some of this is likely adaptive, as different individuals will have different optimal mates. Indeed, mate choice may be more about choosing compatible partners than picking the “best” mate in the absolute sense. Compatibility-based choice can drive or reinforce genetic divergence and lead to speciation. The mechanisms underlying the “taste for the beautiful” determine whether mate choice accelerates or inhibits reproductive isolation. If preferences are learned from parents, or covary with ecological differences like the sensory environment, then choice can promote genetic divergence. If everyone shares preferences for attractive ornaments, then choice promotes gene flow between lineages. OUTLOOK Two major trends continue to shift the emphasis away from male “beauty” and toward how and why individuals make sexual choices. The first integrates neuroscience, genomics, and physiology. We need not limit ourselves to the feathers and dances that dazzled Darwin, which gives us a vastly richer picture of mate choice. The second is that despite persistent structural inequities in academia, a broader range of people study a broader range of questions. This new focus confirms Darwin’s insight that mate choice makes a primary contribution to sexual selection, but suggests that sexual selection is often tangential to mate choice. This conclusion challenges a persistent belief with sinister roots, whereby mate choice is all about male ornaments. Under this view, females evolve to prefer handsome males who provide healthy offspring, or alternatively, to express flighty whims for arbitrary traits. But mate-choice mechanisms also evolve for a host of other reasons Understanding mate choice mechanisms is key to understanding how sexual decisions underlie speciation and adaptation to environmental change. New theory and technology allow us to explicitly connect decision-making mechanisms with their evolutionary consequences. A century and a half after Darwin, we can shift our focus to females and males as choosers, rather than the gaudy by-products of mate choice. Mate choice mechanisms across domains of life. Sensory periphery for stimulus detection (yellow), brain for perceptual integration and evaluation (orange), and reproductive structures for postmating choice among pollen or sperm (teal). ILLUSTRATION: KELLIE HOLOSKI/ SCIENCE« less
5. Mikea, Malagasy, or hunter-gatherers? Scale, ethnicity, and cultural groups in ethnographic description and ethnological analysis

   Tucker, Bram ( January 2022 , Edition Kulturwissenschaft)

   Widlok, Thomas ; Cruz, M. Dores (Ed.)

   Are ethnic units also cultural and sociopolitical units? Barth (1969a) argued that they are not. However, some recent cultural evolutionary studies argue that ethnicity may function to facilitate within-group cooperation and between-group competition, referred to as parochial altruism (Choi and Bowles 2007; García and van den Bergh 2011; Handley and Mathew 2020; Jones 2018). Ethnographers have historically treated ethnicity and culture as equivalent with assertions that X people have particular beliefs, habits, customs, etc. In this paper I explore the ramifications of scale in ethnographic description and generalization, with a focus on my research participants in southwestern Madagascar, whom I usually label with the ethnonyms Mikea, Masikoro, and Vezo, or with the anthropological categories of hunter-gatherers, farmers, and fishermen. These are people who refer to themselves by these same ethnonyms or hyphenated combinations of terms (Masikoro-Mikea, Vezo-Mikea), or as Malagasy, a term referring to all peoples of Madagascar, or by village or clan affiliations. By contrasting evidence from my research (Tucker et al. 2021) with a study by Handley and Mathew (2020) about East African herders, I argue that the appropriate scale for ethnographic description may depend on patterns of similarity and difference in shared cultural traits and social networks,more »and these may be related to, or independent of, historically constituted ethnonyms. Careful thought is required to avoid scalar errors of over-particularization and exoticism (which I call Type 1 scalar errors) and over-generalization and stereotyping (Type 2 scalar errors). Because “ethnicity” is not just one “thing,” ethnicity is not always the proper scale for ethnographic description.« less