Evolutionary Anthropology最新文献

Reproduction is a complex process, and microbes play a far greater role than previously imagined. This review explores the ways that microbiomes influence the rich tapestry of reproductive processes and outcomes within the primate lineage, including pre-copulatory and post-copulatory mechanisms. We discuss microbiomes in a sexual selection framework, specifically how they might influence mate choice and sexual competition across multiple sensory modalities. We then consider how copulatory behavior and mating systems may in turn shape reproductive microbiomes. Moving to post-copulatory processes, we discuss the potential impact of microbes on cryptic choice and sperm competition and call for additional research in this area. Finally, we explore the influence of microbes on pregnancy outcomes, emphasizing evolutionary perspectives often overlooked in clinical research. Importantly, we compare human studies to those on nonhuman primates, bridging the two areas of inquiry and outlining future research directions. Our aim is to highlight the vast potential for microbes to contribute to all stages of reproduction, and to inspire creative, synthetic future research that moves forward this fascinating area of inquiry.

How primates sense, cognize, and respond to death, and are affected by it, are broad research themes within primate thanatology. When primate thanatology adopts a comparative framework, it can illuminate the diversity and evolutionary continuity of psycho-neuro-emotional responses to death and dying across primate species, including humans. Evolutionary or comparative thanatology has recently gained momentum, but it lacks methodological consistency, quantitative rigor, and coherent reporting standards. We attempt to address the lack of standardized approaches by introducing an individual-level comparative framework and employing standard ethological methods, accompanied by well-defined behavioral variables. We argue that the proposed framework can capture individual-specific responses to conspecific death and enable hypothesis-driven studies. The framework is essential to examine the large number of hypotheses that have accumulated in the field.

The 11th annual Northeastern Evolutionary Primatologists (NEEP) meeting was hosted by The University of Pennsylvania (Penn) and held at the Penn Museum from November 7th to November 8th, 2025. Reflecting NEEP's commitment to fostering the next generation of researchers, much of the conference's featured work was presented by undergraduate and graduate students, as well as early career scientists. To kick off the conference, Caroline Jones (Penn) introduced this year's keynote speaker, Dr. Samar Sayeda (American Museum of Natural History). Sayeda's presentation, “From Bones to Behaviour: Evolution of the Human Hand”, explored her research on the functional morphology and evolution of fossil hominin postcrania, highlighting how variations in hand structure and locomotion reveal the diverse behavioral adaptations of early humans. Sayeda first introduced how the human hand transitioned from exhibiting short thumbs to long, dexterous thumbs, and while that is well understood, Sayeda argues that we still are uncertain about when and how humans lost the locomotory use of hands (i.e. knuckle-walking). More importantly, she argues that this time period should be compared to when and how tool use evolved in hominins. To address these questions, Sayeda analyzed both external and internal hand morphology of extant and fossil primates. She then compared these to locomotor and hand behavior. Unlike previous research that analyzed the carpals, Sayeda focused her attention on the phalanges and bone density on both the palmar and dorsal surfaces to predict hand behavior in early hominin species. Her results indicate that some Australopithecus species and Homo habilis both exhibit more “ape-like” hands. In contrast, Au. sediba and H. naledi both have a mix of “ape-like” and “human-like” traits, but not the same combination. Au. sediba shows the possibility of dexterity, but traits that are suggestive of arboreal locomotion are preserved. H. naledi shows traits indicative of ape-like climbing behaviors, as well as evidence of the human-like ability to grip small objects or tools. Her analysis of H. floresiensis' hand reveals a unique pattern not seen in any other species; however, Sayeda reminds us of how H. floresiensis is already a unique case in hominin evolution. Sayeda's findings support the idea that the transition to dexterity-focused hands was a gradual, mosaic process. Furthermore, her data suggest that tool use may have emerged before the appearance of the genus Homo. Moving forward, Dr. Sayeda is interested in extending her analysis to include more fossils, as well as including extant monkey species.

The evolution of laryngeal air sacs in hominins has been a subject of considerable debate, with particular attention given to the inferred presence of air sacs in Australopithecus afarensis and inferred absence in Middle and Upper Pleistocene hominins. We challenge several assumptions prevalent in relevant discourse and assert that (1) while exhibiting morphological similarity, it cannot be ruled out that relationships between hyoid morphology and air sac morphology in extant African great apes may reflect convergence; (2) while the only known A. afarensis hyoid exhibits “ape-like” bulla, this feature may have persisted following the loss of air sacs, and not be indicative of their presence per se; (3) because there are currently only five known hominin hyoid bones represented in the fossil record (with a single specimen predating the Middle Pleistocene) the evidential basis for interpreting air sac presence or absence is minimal; and (4) inferences toward a role of sexual selection and communicative behavior in explicating the loss of air sacs in the hominin lineage are undermined by the atypical sexual dimorphism patterns in early hominins. We advocate for a cautious approach to interpreting hominin behavior and evolution which prioritizes data over speculation, and underscore the need for rigorous evidence when constructing evolutionary narratives about early hominin vocal anatomy and its evolution.

Language is central to the cognitive and sociocultural traits that distinguish humans, yet the evolutionary emergence of this capacity is far from fully understood. This review explores how the study of the brains of language-trained apes (LTAs) offers a unique and valuable opportunity to tease apart the relative contribution of evolved species differences, behavior, and environment in the emergence of complex communication abilities. For example, when raised in sociolinguistically rich and interactive environments, LTAs show communicative competencies that parallel aspects of early human language acquisition and exhibit altered neuroanatomy, including increased connectivity and laterization in regions associated with language. Sustained and enriched early exposure to symbolic experience may also alter molecular pathways, including modifications in the expression of genes involved in synaptic plasticity, neural connectivity, and cognitive function, thus critically underpinning speech and language processing. This theoretical synthesis highlights how research on language-trained apes can inform our understanding of experience-dependent plasticity in distributed neural networks, providing insights into the evolutionary origins of human communication.

Unlike any other great ape, humans give birth to large, secondarily altricial babies, show precocial social development, have bigger brains that require a long maturation period, and engage in cooperative breeding (CB). These traits, which characterize the human adaptive complex, are intricately linked and must have mutually reinforced each other over evolutionary time. Here, we use recent evidence from paleontology, developmental psychology, and pediatrics, complemented with comparative analyses, to ask what may have triggered this coevolutionary feedback loop: bipedality, direct selection on altriciality, a higher-quality diet, or cooperative breeding. An early adoption of extensive allomaternal care during human evolution, that is, the CB-first model, best accommodates the available data. In particular, CB was a catalyst enabling further increases in brain size, because even though larger brains slow down life history and neurodevelopment and thus lead to a demographic dilemma, CB enabled the necessary increase in birth rates.

The unique intellectual and cultural attributes of Homo sapiens that arose during the Middle Stone Age are often ascribed to positive evolutionary development of novel physical or personality traits, but attempts to correlate cultural with genetic evolution have been unsuccessful. Humans are also unique, however, in their ability to ignore or override hormonal and pheromonal instincts that define the social structures and behaviors of other animals. Humans can rapidly invade new environments because they invent rather than inherit such behaviors, which cumulatively we call a culture. Downregulation of instincts makes the invention and learning of cultures necessary, which imposes both an opportunity and a burden on individuals and societies. Cultural evolution enables human societies to invent, promulgate, compete and evolve their social structures in a generation or two rather than the hundreds of generations required for significant genetic evolution. Nevertheless, residual instincts may conflict with and delimit novel cultures and their social structures.