Biological Anthropology in 2018: Grounded in Theory, Questioning Contexts, Embracing Innovation

Abstract

Biological anthropology in 2018 encapsulated what past scholars envisioned for its future: a multidisciplinary approach to understanding human and nonhuman primate evolution and diversity using the most innovative techniques and rigorous standards available. This year also built on a tradition of introspection about what biological anthropology encompasses and by whom and how it is conducted. This review highlights research and movements in the field that reflect both of these pursuits. Studies drew on evolutionary theory to generate novel insights into human and nonhuman primate biology, behavior, and organization. Studies on hominin evolution and human biology have upended previous understandings by revealing more dynamic and context-dependent processes in our ancestry and phenotypic expressions. Across subdisciplines, biological anthropologists have advanced the use of new technologies and analytical techniques and begun to promote open, transparent, and reproducible science among a more diverse community of researchers. [year in review, evolutionary anthropology, context and variation, emerging technologies, transparent methods, researcher diversity] RESUMEN La biologı́a antropológica en 2018 encapsuló lo que investigadores anteriores imaginaron para su futuro: una aproximación multidisciplinaria para entender la evolución de primates humanos y no humanos y diversidad utilizando las técnicas más innovadoras y los estándares rigurosos disponibles. Este año también desarrolló sobre una tradición de introspección acerca de lo que la antropologı́a biológica abarca y por quién y cómo es llevada a cabo. Esta revisión resalta la investigación y los movimientos en el campo que reflejan estas búsquedas. Los estudios se basaron en la teorı́a evolucionaria para generar nuevos conocimientos en la biologı́a de primates humanos y no humanos, comportamiento y organización. Los estudios sobre la evolución de los homı́ninos y la biologı́a humana han cambiado drásticamente entendimientos previos al revelar procesos más dinámicos y dependientes del contexto en nuestra ascendencia y expresiones fenotı́picas. A través de las subdisciplinas, los antropólogos biológicos han avanzado el uso de nuevas tecnologı́as y técnicas analı́ticas y empezado a promover una ciencia abierta, transparente y reproducible entre una comunidad más diversa de investigadores. [año en revisión, antropologı́a evolucionaria, contexto y variación, tecnologı́as emergentes, métodos transparentes, diversidad de investigadores] T history of biological anthropology has been underscored by attempts to properly situate the field in relation to other natural sciences and the discipline of anthropology as a whole (e.g., Calcagno 2003; Ellison 2018; Fuentes 2010; Wiley and Cullin 2016). Today, there are three biologically and/or quantitatively oriented sections AMERICAN ANTHROPOLOGIST, Vol. 121, No. 2, pp. 417–430, ISSN 0002-7294, online ISSN 1548-1433. C © 2019 by the American Anthropological Association. All rights reserved. DOI: 10.1111/aman.13233 within the American Anthropological Association (AAA)— the Biological Anthropology Society, the Evolutionary Anthropology Society, and the Society for Anthropological Sciences—which nearly every year confront their minority status within the AAA and at times larger questions about the positionality and representation of science within the 418 American Anthropologist • Vol. 121, No. 2 • May 2019 discipline (e.g., Lende 2010). This year was marked by a fresh level of introspection as another scientific anthropological organization, the American Association of Physical Anthropologists (AAPA), marked the centennial of its flagship journal (the American Journal of Physical Anthropology, or AJPA) and simultaneously began to consider changing the name of the organization. In effect, 2018 was a year for contemplating what the field has been and where it is going. The debate about what, if any, new name might better represent the current scope of the AAPA and its members is ongoing but has parallels in earlier deliberations about the aims of the field. As reviewed by Ellison (2018) in the centennial AJPA issue, and earlier by Fuentes (2010), major players in the mid-twentieth century recognized the need to definitively move away from the “old” physical anthropology— with its emphasis on descriptive taxonomy—and toward a “new” multidisciplinary approach aimed at understanding “the process of primate evolution and human variation by the most efficient techniques available” (Washburn 1951, 298). Washburn’s vision of this new approach is remarkably still apt given the new perspectives and theoretical and technological developments that have come to dominate the field since its mid-century inception (Fuentes 2010; see also essays by Cartmill 2018, Grauer 2018, Leonard 2018, Richtsmeier 2018, Weiss 2018, and others in the 2018 AJPA centennial issue). Inspired by this “new” definition of physical anthropology, I have chosen to highlight research published in 2018 that is strongly grounded in evolutionary theory, expands our understanding of context, variation, and dynamic process in human evolution and biology, or introduces new methods and approaches that move the field forward. Many articles highlighted in this review accomplish all of the above. Many more are not in this review but are no less exemplary in their theoretical rigor, methodological innovation, and significance to the field. GROUNDED IN EVOLUTIONARY THEORY One of the alternate names proposed for the AAPA was the “American Association of Evolutionary Anthropologists,” a suggestion that acknowledges both the primacy of evolutionary studies and the fact that evolutionary theory and related mechanisms are dominant and unifying frameworks for interpreting variation in all primate biology and behavior (Ellison 2018). While the descriptive does not characterize all concentrations within biological anthropology, the frequent use of evolutionary theory to generate and test predictions does distinguish our field from other anthropological subfields and social and health sciences. For example, anthropologists have long posited that life-history tradeoffs in growth versus maintenance—and not merely nutritional quality—underlie epidemiological patterns of growth faltering in resource-poor environments (Blackwell et al. 2010; Bogin et al. 2018; McDade et al. 2008). Urlacher et al. (2018) provided new evidence of the etiology of this trade-off, demonstrating that linear growth in Shuar children (Ecuador) was most adversely affected by short-term deficits related to acute inflammation. However, the effect was buffered by greater body fat, as would be predicted when growth and immune function directly compete for energetic resources. Several studies demonstrated novel evidence of sexual selection influencing population-specific differences in mating, parental investment, biology, and economic activities. Lowe, Hobaiter, and Newton-Fisher (2018) found support for their “risky-male avoidance hypothesis” in observing that eastern chimpanzee mothers whose infants were most vulnerable to infanticide specifically avoided rising-rank males who were less likely to have previously sired infants and thus most incentivized to commit infanticide. Conversely, male mountain gorillas who indiscriminately affiliated with more infants were also shown to sire more infants, suggesting that female preference for affiliative males may drive emergent selection for more costly paternal behaviors (Rosenbaum, Vigilant, et al. 2018). To test for evidence of sexually selected chemical communication, Spence-Aizenberg, Williams, and FernandezDuque (2018) examined physical and behavioral differences in olfactory traits between captive male and female owl monkeys. Hypothesizing that traits would be female-biased as a result of male selection on female quality, they found a mix of femaleand male-biased dimorphic traits that were consistent with the species’ strict social monogamy, on the one hand, but inconsistent with their high paternal care, on the other hand. The authors raise the possibility that sex differences in odors may bias olfactory behaviors among males and females without corresponding to extreme dimorphism in olfactory physiology. Turning to humans, von Rueden et al. (2018) found that among the Tsimane—egalitarian foragerfarmers of the Bolivian Amazon—men’s greater political influence stemmed in part from sex differences in body size, parental investment costs, and division of labor but was also due to the increased access to cooperative partners that these latter characteristics beget. Evolutionary theory and mechanisms can also be combined with or evaluated against other frameworks for understanding human and nonhuman primate behavior. Alami et al. (2018) applied life-history theory to expand on the psychological concept of a “health locus of control” (HLC)—that is, the extent of control individuals believe they have over their own health outcomes. Alami et al. demonstrated that Tsimane adults have significantly lower HLC compared with adults in Japan and the United Kingdom—likely a reflection of higher extrinsic risks in the Tsimane environment. Lower HLC within the Tsimane also predicted lower uptake of biomedical illness treatments, with implications for health policy and interventions in high-mortality populations. Social network theory posits that individual behavior can be explained in relation to a person’s position in a network of relationships. Ready and Power (2018) applied social network analysis to assess food-sharing patterns in a Martin • Biological Anthropology in 2018 419 Canadian Inuit village, demonstrating that both evolutionary mechanisms (e.g., reciprocity and kin selection) and social structural forces (e.g., local political prominence) motivated more frequent sharing. Specifically, they found that more affluent and politically influential households both shared more (rather t