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The evolution of physical anthropology

2018; Wiley; Volume: 165; Issue: 4 Linguagem: Inglês

10.1002/ajpa.23408

1096-8644

Peter T. Ellison,

Evolutionary Game Theory and Cooperation

The old physical anthropology was primarily a technique. The common core of the science was measurement of external form with calipers. The new physical anthropology is primarily an area of interest, the desire to understand the process of primate evolution and human variation by the most efficient techniques available (Washburn, 1951, p. 298). This year, 2018, marks the centennial of the founding of the American Journal of Physical Anthropology, a notable milestone for the journal, for the American Association of Physical Anthropologists which it represents, and for the larger field of inquiry chronicled in its pages. To celebrate this milestone, I invited my predecessor Editors-in-Chief of the AJPA to join me in assembling a special, centennial issue. We solicited contributions from a number of our colleagues, representing, if not entirely encompassing, the diversity of subfields within physical anthropology. We asked the contributors to reflect on the changes that have occurred since the journal was founded and its role in those changes. In inviting these special contributions, called “Centennial Perspectives,” we granted the authors a great deal of scope as to content and style. The space available is obviously insufficient for comprehensive reviews. Instead, we encouraged the authors to provide their personal perspectives, to identify what seemed to them important and to draw out the themes that they found striking. The result is a wonderful collection of essays that not only look backward on the development of the discipline of physical anthropology, but forward to its future. We expect that they will be of broad interest, both to newer students and to seasoned researchers, and that they may even be of interest to future generations of students and researchers as a penetrating exercise in self-assessment conducted early in the 21st century. Many of the Centennial Perspectives make note of Washburn's call for a “new physical anthropology,” and virtually all implicitly or explicitly evoke the relationship of changes in the area they are covering to developments in evolutionary theory. However, none of them directly consider those changes as a central axis running through the history of our discipline. As an introduction to the entire issue, therefore, it may be useful to briefly consider what has been an extremely dynamic century for the larger field of evolutionary biology and its impact on physical anthropology. Table 1 presents a rough timeline of some of the key developments and seminal publications in evolutionary theory since the beginning of the 20th century. In some instances, the references given are to fundamental individual contributions; in other places the references are representative of larger and more dispersed bodies of work. Although incomplete and reflecting my own interests and limitations, the table provides a sense of the dynamic nature of evolutionary theory during the past century. At the time of the founding of the AJPA in 1918, the state of evolutionary theory was much as Darwin had left it, though that was about to change. Hugo DeVries and Carl Erich Correns attended a meeting of the Royal Horticultural Society in 1899 at which they heard William Bateson present a article on “Hybridization and cross-breeding as a method of scientific investigation” (Bateson, 1900). These three pioneers of early genetics all became aware of the earlier work of Mendel at about the same time, with Correns making the first direct citation of it (Correns 1900). In the same year as the founding of the AJPA, R. A. Fisher (1918) published the first article incorporating the Mendelian notion of particulate inheritance into population genetics, arguably laying the initial brick in the edifice that would become the “modern synthesis” of evolutionary biology. The 1920's and 1930's saw Fisher (1930), Haldane (1924, 1932), and Wright (1921, 1931, 1932) develop a comprehensive mathematical theory of evolution in terms of population genetics. In the process, Wright introduced the concept of a “fitness landscape,” Haldane applied evolutionary genetics to explain the increasing frequency of the melanistic form of the moth Biston betularia as an example of natural selection operating in historical time, and Fisher combined the mathematics of demography with that of population genetics, formulating the concept of “reproductive value” and setting the stage for the later development of life-history theory. E. B. Ford, who was a close friend and coworker of Fisher's, influenced him with his own work on genetic polymorphism and the potential for strong coefficients of selection in nature (Ford, 1931). An expert in lepidoptera, Ford encouraged his student, Bernard Kettlewell, to investigate the phenomenon of industrial melanism in Biston betularia that Haldane had described, leading to famous experiments that supported the notion of contemporary natural selection in this species based on differential predation related to coloration (Kettlewell, 1955). This work would later feature prominently in Ford's Ecological Genetics (1964). Two other landmark publications in the 1930's were G. F. Gause's The Struggle for Existence (Gause, 1934) and Dobzhansky's Genetics and the Origin of Species (Dobzhansky, 1937). Gause used experimental work in microbiology (Gause, 1932, 1934) to develop basic concepts in evolutionary ecology, including competitive exclusion and population pressure, laying the foundation for niche theory, and demonstrating the ecological importance of the logistic growth model championed by Raymond Pearl. Dobzhansky's book was the first comprehensive volume uniting population genetics with evolutionary theory. Ernst Mayr would later call its publication “clearly the most decisive event in the history of evolutionary biology since the publication of the Origin of Species” (Mayr, 1982). The other major architects of the “modern synthesis” published their own seminal volumes over the next decade, Mayr's Systematics and the Origin of Species from the Viewpoint of a Zoologist (1942), George Gaylord Simpson's Tempo and Mode in Evolution (1944), and G. Ledyard Stebbins' Variation and Evolution in Plants (1950). Among the important contributions made by each can be counted the formulation of the “biological species concept” (that “species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups”) and the description of allopatric speciation by Mayr, the ability of microevolutionary processes to account for the macroevolutionary patterns of paleontology by Simpson, and the importance of cross-fertilization, self-fertilization, and polyploidy in the evolution of plants by Stebbins. In 1942, Julian Huxley, grandson of Thomas H. Huxley, coined the term “modern synthesis” for this grand intersection of genetics, paleontology, zoology, and botany with evolutionary theory (Huxley, 1942). Although the seminal impact of the modern synthesis is unquestioned, many of its specifics did not go unchallenged. Experts in phenetic classification were particularly critical of Mayr's biological species concept (Ehrlich, 1961, Sokal & Crovello, 1970), even going so far as to assert that “the generalization that organisms exist as distinct species is largely invalid” (Ehrlich & Holm, 1963). Mayr's insistence on the importance of allopatric speciation as the dominant mode of cladogenesis was also challenged and gave way to a much richer understanding of this fundamental process (White, 1978). Critical reevaluation of the modern synthesis continues to the present (e.g., Gawne, McKenna, & Nijhout, 2018). In 1972, Eldridge and Gould notably challenged Simpson's position regarding the dominance of microevolutionary process in accounting for the paleontological record in their paper on “punctuated equilibria,” arguing that different, macro-level of evolutionary processes, including differential rates of speciation and species extinction, must be evoked to account for macro-evolutionary patterns in the fossil record. In 1973, Van Valen pushed this notion further, arguing that extinction of groups and higher taxa occurs at stochastically constant rates. The embrace of such arguments by many paleontologists, in particular, led to a new focus on macro-, as opposed to micro-, evolutionary process in shaping existing taxonomies (Stanley, 1979). From the 1950's to the 1970's increasing attention to the relationship between demography and evolution led to rapid and profound developments in evolutionary ecology, life-history theory, and the theory of social evolution. David Lack (1954), in The Regulation of Animal Numbers, made the crucial distinction between maximum reproduction and optimal reproduction, later known as “Lack's Principle,” that is, that “the clutch size of each species of bird has been adapted by natural selection to correspond with the largest number of young for which the parents can, on average, provide enough food.” In 1962, V. C. Wynne-Edwards published Animal Dispersion in Relation to Social Behavior, in which he expounded the theory that would become known as “group selection,” arguing that animals self-regulated their population densities to avoid over-population and extinction. These two volumes became the initial poles of a continuing tension between proponents of individual and group-level selection. Championed by Maynard Smith (1964) and Williams (1972), individual selection pushed group selection into the shadowlands of heresy for decades. Recently, however, interest in multi-level selection has regained academic legitimacy (Maynard Smith & Szathmáry, 1995; Wilson & Sober, 1994) if not universal acceptance. The seminal work of William D. Hamilton (1964) on inclusive fitness ushered in a dramatic expansion of evolutionary theory into the realm of social behavior. Genetic relatedness became a key to understanding social organization and social behavior in group-living species (Trivers & Hare, 1976; Wilson, 1975). Trivers (1971) extended the logic of “sociobiology” to include the evolution of reciprocal altruism between unrelated individuals. This approach was further refined by Maynard Smith and Price (1973) who introduced the analytical framework of game theory to evolution and the notion of an “evolutionarily stable strategy.” This foundational work was soon generalized to a broad theory of cooperation (Axelrod & Hamilton, 1981), and paved the way for cultural evolution theory (Boyd & Richardson, 1988, 2009). Attention to relatedness between individual actors not only spawned theories of cooperative behavior, but also theories of conflict, including conflicts between male and female reproductive strategies (Trivers, 1972), parent-offspring conflict (Trivers, 1974), and intra-genomic conflict (Haig, 1993). Additional developments in evolutionary theory deriving from the attention to demography and ecology and their interaction with evolution included theories of biogeography and species abundance (MacArthur, 1965), life-history theory (Stearns, 1976), the theory of sex allocation (Charnov, 1982; Hamilton, 1967; Trivers & Willard, 1973), and optimal foraging theory (Stephens & Krebs, 1986). One of the newest developments in evolutionary theory is the recognition that developmental plasticity and epigenetic processes may lead to trans-generational effects (Gluckman & Hanson, 2004; West-Eberhard, 2003). In some ways, this new perspective was anticipated by Waddington (1942) in the early days of the modern synthesis in his concepts of epigenetic landscape and genetic assimilation. S. J. Gould's Ontogeny and Phylogeny, published in 1977, argued for the importance of changes in developmental timing and sequence as fundamental process underlying evolutionary changes in morphology, helping to spur the growing field of “evo-devo.” In the field of epidemiology, Barker and Osmond (1986) drew attention to strong correlations between early life conditions and chronic disease in later life. As a result, this new aspect of evolutionary theory has had a particularly prominent impact in the field of evolutionary medicine (Nesse & Williams, 1996). The above chronology only skims the surface of the field of evolutionary theory during the past century, no doubt omitting many developments that others will consider key. However, it suffices to identify a number of the advances that are of relevance to biological anthropology and to allow consideration of their influence on our field. The equivocal status of evolutionary theory at the time of the founding of the American Journal of Physical Anthropology can be appreciated from reading Alěs Hrdlička's review and manifesto, “Physical anthropology: Its scope and aims; its history and present status in America” (Hrdlička, 1918), which appeared as the first paper in the new journal and continued in subsequent installments throughout the first year. (See the Centennial Perspective by Little for details regarding the founding of the AJPA). In this cornerstone document Hrdlička presents the development of physical anthropology in the United States as a natural continuation of earlier trends in Europe that had seen the founding of the Société d'Anthropologie in Paris in 1859 and sister societies soon after in England (1863) and Germany (1869). Notably absent, though, is any reference to the publication of the Origin of Species (Darwin, 1859) in the same year as the founding of the French society, or to The Descent of Man, and Selection in Relation to Sex (Darwin, 1871) published shortly after the founding of the German society. Hrdlička's list of direct contributors to the emergence of physical anthropology includes Cuvier and Lamarck but conspicuously omits Darwin. [Physical anthropology] can be defined today in the briefest form as the study of man's variation. It is that part of Anthropology, which occupies itself in a comparative way with the study of the human body and its inseparable functions. It deals with the causes and ways of human evolution, and with the development, transmission, classification, effects, and tendencies of man's bodily and functional differences. It is, briefly and comprehensively, the research into man's anatomical and physiological variation. (Hrdlička, 1918, p. 4, emphasis in original) Finally, the ultimate aim of Physical Anthropology is that it may, on the basis of accumulated knowledge and together with other branches of research, show the tendencies of the actual and future evolution of man, and aid in its possible regulation or improvement (Hrdlička, 1918, p. 21). The many striking resemblances between man, ape, and monkey in early development, and their frequently closely corresponding growth changes can only be explained by one common origin, from which they all inherited the tendency for the same ontogenetic processes which could only become modified through later specializations. A further general conclusion, which the author considers as safe, is that man in some respects is less specialized and has hence remained phylogenetically as well as ontogenetically more original and “primitive” than various other primates (Schultz, 1924, p. 163). Neither Hooton nor Schultz cite any works of evolutionary theory, however, in developing their arguments, though both implicitly rely on notions of evolultionary processes commonly held, and often incorrect, prior to the modern synthesis. These notions are more explicitly on display in the differing accounts of human origins presented by Henry Fairfield Osborn (1930) and William K. Gregory (1930), the nub of their debate being when the lineage leading to humans diverged from those of other hominoids. Among the “principles” of evolutionary taxonomy that both subscribe to are the principle that “The remote common ancestors of man and the anthropoids could not have lost any of the characters which have been lost by the modern apes and retained by man” (Gregory, 1930, p. 128), and “Dollo's principle” that “the evolution of anatomical organs is never reversible even though the evolution of functions and habits is frequently reversible” (Gregory, 1930, p. 135; Osborn, 1930, p. 6). Both explicitly cite the “Lamarck-Darwin hypothesis” of an “ape-man” stage of human evolution in developing their own arguments. However, neither appears to be aware of the new work in population genetics and evolutionary theory being carried out by Fisher, Haldane, and Wright. In 1940 Marcus S. Goldstein published an analysis of papers published in the AJPA and in the slightly newer journal, Human Biology (founded by Raymond Pearl in 1929), since their inceptions. The dominant subject areas in the AJPA over that period were “anatomy” (54.1% of articles published) and “methodology” (13.2%). “Group biology,” that is, racial classification and description, was initially a major category of publication in the AJPA (17.8% in the period 1918–1921), but declined to half that percentage after the inauguration of Human Biology, where it was the dominant category of publication (42.6%). “Evolution” was a minor category in both journals, 6.8% in the AJPA and 3.7% in Human Biology. “Genetics” was also a minor category (4.5% in the AJPA and 9.9% in Human Biology). Those papers that were devoted to genetics did not generally show any influence of the new evolutionary theory of population genetics, but rather used characters such as blood-group frequencies as one more “trait” on which to base classificatory distinctions (e.g., Boyd & Boyd, 1941). [Montagu] accuses the physical anthropologists of pre-Mendelian thinking as regards race. In the first two chapters of this belligerent treatise Montagu attempts to show “the meaninglessness of the anthropological conception of race” by identifying it alternatively with biological taxonomy and racism, and at the same time holding up for comparison what to his way of thinking is the only useful concept, namely, that of genetics (Anon, 1944, p. 321). Two years later Alice M. Brues (1946) published an important and quite comprehensive study of the genetics of eye color in which she makes explicit use of and reference to the work of Fisher and Haldane. And in 1949, the year before the Cold Spring Harbor Laboratory symposium at which Washburn issued his call for a “new physical anthropology”, he incoprporated many insights from the new population genetics theory into his review of Keith's (1949) A New Theory of Human Evolution, noting, for example, “The relation of population size to rate of evolution has been extensively investigated, and the conclusions are essentially the same as Keith's,” and “The physical differences between many human groups show that there has not been random mating between humans” (Washburn, 1949, p. 266). The “old” and “new” versions of physical anthropology coexisted and even intermingled like sibling species for many years, though with the balance shifting ever in favor of the “new” version as an understanding an appreciation of the modern synthesis spread through the ranks of physical anthropology in the U.S. Nowhere is the hybrid nature of the transitional period between the “old” and “new” physical anthropologies more apparent than in the debates over the biological “objectivity” of human racial classification that dominated much of the 1950's. (See Centennial Perspective by Rachel Caspari for more detail.) In general, genetic traits are substituted for morphological ones and the effects of natural selection and geographic isolation are evoked. However, little understanding of population genetics in any formal sense, or key concepts such as gene flow, effective population size, random drift, assortative mating, or other processes that influence variation within and between populations, is on display. Telling examples include Carleton Coon, Stanley Garn, and Joseph Birdsell's (1950) important monograph, Races: A Study of the Problems of Race Formation in Man and William C. Boyd's (1950) Genetics and the Races of Man. These authors and many others continued to defend typological classifications using new techniques to support old conclusions, despite incisive critiques by the likes of Montagu (1951) and Stewart (1951), pointing out the methodological and theoretical flaws in typological classifications. Nevertheless, more sophisticated and dynamic perspectives on genetic polymorphisms and their determinants, perspectives explicitly founded on the central concepts of populations genetics such as the balancing of drift and selection, exemplified by the important work of Brues (1954) and William C. Glass (1956) on blood-group polymorphisms, became more important over time and gained the ascendancy by the end of the decade. The study of human paleontology was perhaps the branch of physical anthropology most closely tied to the theory of evolution by natural selection. (See Centennial Perspectives by Trinkaus and by Cartmill.) During the 1950's and 60's, “population thinking”, championed by Ernst Mayr and Theodosius Dobzhansky, began to supplant the typological approach of earlier decades that had led to excessively speciose hominid taxonomies. Niche division among contemporaneous species of hominids was evoked through evidence of differing dietary adaptations, and questions of sympatric speciation driven by competitive exclusion versus allopatric speciation driven by reproductive isolation were debated. Population thinking also lead to the incorporation of newer methods of multivariate statistical analysis into the field of morphometrics to help identify and discriminate groups from metric characters. Debate over the validity of a purely cladistic approach to taxonomy grew heated and persisted into the 1980's. (See Centennial Perspective by Cartmill.) Taxonomic studies in primatology and paleoanthropology were further impacted by the introduction of the notion of “molecular clocks.” Based on assumptions of relatively constant rates of “neutral” genetic change, this new approach not only allowed for the construction of phylogenies for extant species, but also for the extrapolation of divergence dates. The tension between phylogenies based on morphology and fossil dating on the one hand, and genetic similarity and molecular clock dating on the other, was necessarily grounded in evolutionary theory and the assumptions that were made on both sides of the debate. The study of human variation was also transformed during the 1950's and 1960's, emerging from the anti-theoretical, descriptive period of the 30's and 40's dominated by Franz Boas and his contemporaries. (See Centennial Perspective by Caspari.) Raymond Pearl, who founded the journal Human Biology in 1929, helped to introduce new concepts of population ecology into the field, including the logistic model of population growth and its corollary notions of carrying capacity, feedback, and population pressure, ideas that Gause (1932) developed in his experimental models of competition and population growth. The “new” human biology was most prominently on display as part of the International Biology Program which had Human Adaptability as one of its foci. (See Centennial Perspective by Leonard.) While the goals and methods of the Human Adaptability Project, as it came to be called, did not explicitly evoke evolutionary theory, its aims could easily be called an exploration of human norms of reaction (Weiner, 1964). That is, the project explicitly set out to examine how human populations adapted to diverse ecological conditions, including high altitude and arid savanna. Although genetic variation was explicitly considered, an underlying assumption was that behavioral, physiological, and developmental responses to environmental challenges were largely responsible for the spread of humans into virtually all the available habitats on the globe. Even as the advances of the “modern synthesis” were being consolidated into the “new physical anthropology” during the 1950's to the 1970's, a renaissance of Darwinian thinking was beginning to take place in evolutionary biology. Two important foci for this renaissance were new approaches to the evolution of behavior and the elaboration of life-history theory. The new approach to behavioral evolution grew out of the debate over group selection and the evolutionary problem of altruism. As noted above, George Williams prominently championed individual selection while William D. Hamilton laid out an explicit genetic theory of inclusive fitness based on degrees of relatedness and Robert Trivers expounded theories of reciprocal altruism and parent-offspring conflict. In the popular realm, the books of Robert Ardrey painted explicit evolutionary scenarios that attempted to integrate new research on human paleontology with a rather group-selectionist take on the evolution of human social behavior while Richard Dawkins introduced the lay public to the more individual and gene-centered perspectives. The publication of Edward O. Wilson's landmark tome, Sociobiology, in 1975 followed soon after by his Pulitzer-Prize-winning On Human Nature (Wilson, 1978), ushered in a period of intense research and debate within physical anthropology as well as the broader discipline of anthropology as a whole regarding the validity and utility of the new understanding of behavioral evolution. Some rejected the approach as excessive biological reductionism (e.g., Sahlins, 1976). Others, however, advanced compelling analyses that demonstrated the power of the new approach. Many of the most persuasive examples within physical anthropology came from field studies of primate behavior, such as Sarah Blaffer Hrdy's (1977) study of infanticide among Hanuman langurs (1980) and Richard Wrangham and Barbara Smuts’ ecological theory of female-bonded chimpanzee groups (1980). The often-conflicting nature of male and female reproductive strategies within the same species was highlighted by these and other studies, often evoking Trivers’ theoretical work on parental investment. This approach soon spread to the nature of human sex differences, engendering vigorous debate even among adherents of the neo-Darwinian perspective (Hrdy, 1981; Symons, 1981). The expanding impact of the new approach to the evolution of behavior was perhaps particularly apparent in the new field of hunter-gatherer studies. (See the Centennial Perspective by Hawkes, Blurton-Jones, and O'Connell in this issue for more details.) The seminal “Man the Hunter” conference organized by Richard Lee and Irven Devore in 1966, followed by the edited volume of the same name (Lee & DeVore, 1968) ushered in a period of focused research on extant forager populations as models of Pleistocene human ecology. Long-term field studies, such as the Harvard Kalahari Project and the Utah Ache Project, brought careful quantitative methods to bear on documenting hunter-gatherer ecology, social and subsistence behavior, demography, growth and development, material culture, and many other areas of life and biology. Among the aspects of evolutionary theory that were featured in these studies were newly developed models of optimal foraging. Optimal birth spacing hypotheses were also developed by Konner and Worthman (1980), based on breastfeeding behavior, and Blurton-Jones and Sibley (1978), based on the physical burden of carrying dependent offspring while foraging, and related to the theoretical framework that had been introduced by David Lack. Equally impactful were the careful demographic studies of Nancy Howell among the Dobe! Kung (1979) and Kim Hill and Magdalena Hurtado among the Ache of Paraguay (1996). These studies provided explicit empirical links to the mathematical models of life-history theory. Life-history theory was born of the union of mathematical demography and population genetics in the work of R. A. Fisher, as noted above. It was revived as a branch of evolutionary ecology in the 1960's and 70's, addressing the essential trade-offs that appeared to be manifest in the mortality and fertility schedules of organisms. The work of Eric Charnov was particularly influential on many biological anthropologists in addressing such questions as the optimal timing of first reproduction. At the same time that this highly formal theory was being developed, a more empirical approach to the question of the timing of menarche in human females was being pursued by Frisch and Revelle (1971). The Frisch hypothesis of a critical (later minimum) weight (later fatness) necessary for menarche (and later the maintenance of menstruation in older females) touched off significant debate among physical anthropologists and demographers over the mechanisms of human fertility regulation. But both the Frisch hypothesis, and life-history theory as developed by Gadgil and Bossert (1970) and Charnov and Schaffer (1971), among others, drew attention to the role of energy allocation among competing physiological categories as the metabolic framework within which life-history “decisions” were implemented in organisms, including humans. This perspective was soon brought to bear on reproductive physiology more broadly (Ellison, 2001), growth and development, immune function, aging, and other aspects of life course biology. Life-history theory also has had an impact on human and primate paleontology. Among the notable examples of that impact one can cite the work of B. H. Smith (1991) in reconstructing the life histories of extinct hominids, Aiello and Wheeler's (1996) “expensive tissue hypothesis” regarding the energetic tradeoffs of neural and gut tissue, and Rosenberg and Trevathan's (1995) work on the evolution of childbirth. Similarly, life-history theory has become a central framework in primatology (Alberts et al., 2013). An additional important infusion of evolutionary theory into biological anthropology has come with the explosion of techniques in genetics and genomics since the 1990's. (See Centennial Perspectives by Weiss and by Szathmáry.) While technological advances have led the way, important theoretical proposals have been made as well. Gluckman and Hanson (2004) have championed the idea that epigenetic mechanisms may allow a developing organism to “predict” important aspects of its adult environment and to adjust its developmental trajectory to attain an adult phenotype optimal for that prediction. While these mechanisms are purported to have evolved to support adaptive developmental adjustments, they are also considered to result in maladaptive “mismatch” when the signals that previously predicted adult environments become unreliable (Gluckman & Hanson, 2006). Kuzawa (2007) has argued a different position, suggesting that epigenetic signals are consolidated across generations, leading to a pattern of development “inertia” that adaptively tracks environmental changes that occur over a medium timeframe, longer that then developmental period of an individual human but shorter than the multigenerational timeframes that typify natural selection. Both of these scenarios challenge the conventional population genetic theory of the modern synthesis in ways that sometimes seem almost Lamarckian. David Haig (1993) demonstrated the impact of genetic imprinting and conflict between maternal and paternal genomes on human health and development, uniting this newly identified aspect of genomic biology with the evolutionary theory of sexual selection, conflicting reproductive strategies, and parent-offspring conflict. This work complemented the burgeoning interest in epigenetic and developmental plasticity, leading to new attention to maternal-fetal-infant interactions and the mediating influence of the placenta (Rutherford, 2013) and milk (Hinde, 2009). Many if not all of the newest “cutting edges” of biological anthropology are deeply informed by evolutionary theory. “Evo-devo” has become the rubric for the integration of developmental and evolutionary change, focusing attention more on the regulation of gene expression than on changes in exon coding. The work of Capellini and Dingwall (2017) on the evolution of limb proportions in primates is a compelling example. The ability to extract and decipher DNA from fossils has led to new understandings of the broad features of human migrations and the peopling of the world, and has drawn attention to genetic introgression as an important process (Sankararaman, Mallick, Patterson, & Reich, 2016). Cultural evolutionary studies are building rapidly on the foundations laid by the Darwinian renaissance and leading to new appreciation for multilevel selection (Henrich, 2017). The impact of developments in evolutionary theory on specific topics and sub-fields within physical anthropology is more clearly and adequately demonstrated in many of the other Centennial Perspectives in this issue. Clearly, Washburn's vision has been justified, and physical anthropology has positioned itself comfortably within the larger field of evolutionary biology. Along with this repositioning has come the development and incorporation of new techniques and the recognition of broader responsibilities in the modern world. (See Centennial Perspectives by Turner and by Strier.) But a further question begged by this repositioning is whether the discipline of physical anthropology, the American Association of Physical Anthropologists, and its flagship journal, the American Journal of Physical Anthropology, are still well-represented by their names. Many departments, sub-departments, and programs formerly known as “physical anthropology” have shifted their names in the past decades, most commonly to biological anthropology but also to other variations. In part, this trend has been fueled by the sense that “physical anthropology” as a rubric is more appropriate to what Washburn had referred to as the “old” form of the discipline and that it is neither descriptive of nor evocative of the contemporary field of study and research. In my own opinion, the best name for our discipline at this point would be “evolutionary anthropology,” reflecting the fact that the core of the discipline is the study of human evolution and that the guiding theoretical framework is evolutionary theory. (There may be some sub-fields, e.g., forensics, bioarchaeology, that are less impacted by evolutionary theory, but even they are not immune to its influence, as can be seen from the Centennial Perspectives by Ubelaker and by Larsen.) As the global community of interest represented by our discipline considers its history and its trajectory, it might be worth considering as well whether the discipline itself has evolved into something deserving of a new name.