Humans prioritize close, positive relationships during aging, and socioemotional selectivity theory proposes that this shift causally depend on capacities for thinking about personal future time horizons. To examine this theory, we tested for key elements of human social aging in longitudinal data on wild chimpanzees. Aging male chimpanzees have more mutual friendships characterized by high, equitable investment, whereas younger males have more one-sided relationships. Older males are more likely to be alone, but they also...

Humans have relied on sourdough starter microbial communities to make leavened bread for thousands of years, but only a small fraction of global sourdough biodiversity has been characterized. Working with a citizen-scientist network of bread bakers, we determined the microbial diversity of 500 sourdough starters from four continents. In sharp contrast with widespread assumptions, we found little evidence for biogeographic patterns in starter communities. Strong co-occurrence patterns observed in situ and recreated in vitro demonstrate...

Background: Understanding adaptation involves establishing connections between selective agents and beneficial population responses. However, relatively little attention has been paid to seasonal adaptation, in part, because it requires complex and integrative knowledge about seasonally fluctuating environmental factors, the effects of variable phenology on exposure to those factors, and evidence for temporal specialization. In the European corn borer moth, Ostrinia nubilalis , sympatric pheromone strains exploit the same host plant ( Zea mays ) but may...

In humans, senescence increases susceptibility to viral infection. However, comparative data on viral infection in free-living non-human primates—even in our closest living relatives, chimpanzees and bonobos (Pan troglodytes and P. paniscus)—are relatively scarce, thereby constraining an evolutionary understanding of age-related patterns of viral infection. We investigated a population of wild eastern chimpanzees (P. t. schweinfurthii), using metagenomics to characterize viromes (full viral communities) in the feces of 42 sexually mature chimpanzees (22 males, 20 females)...

Genetically encoded fluorescent glutamate indicators (iGluSnFRs) enable neurotransmitter release and diffusion to be visualized in intact tissue. Synaptic iGluSnFR signal time courses vary widely depending on experimental conditions, often lasting 10-100 times longer than the extracellular lifetime of synaptically released glutamate estimated with uptake measurements. iGluSnFR signals typically also decay much more slowly than the unbinding kinetics of the indicator. To resolve these discrepancies, here we have modeled synaptic glutamate diffusion, uptake and iGluSnFR activation...

The typical marine animal has increased in biovolume by more than two orders of magnitude since the beginning of the Cambrian, but the causes of this trend remain unknown. We test the hypothesis that the efficiency of intra-organism oxygen delivery is a major constraint on body size evolution in marine animals. To test this hypothesis, we compiled a dataset comprising 13,723 marine animal genera spanning the Phanerozoic. We coded each genus according to its respiratory...

Cortisol, a key product of the stress response, has critical influences on degenerative aging in humans. In turn, cortisol production is affected by senescence of the hypothalamic-pituitary-adrenal (HPA) axis, leading to progressive dysregulation and increased cortisol exposure. These processes have been studied extensively in industrialized settings, but few comparative data are available from humans and closely-related species living in natural environments, where stressors are very different. Here, we examine age-related changes in urinary cortisol in...

While declining physical performance is an expected consequence of aging, human clinical research has placed increasing emphasis on physical frailty as a predictor of death and disability in the elderly. We examined non-invasive measures approximating frailty in a richly-sampled longitudinal dataset on wild chimpanzees. Using urinary creatinine to assess lean body mass, we demonstrated moderate but significant declines in physical condition with age in both sexes. While older chimpanzees spent less of their day in...

Synchronized and quasi-periodic production of seeds by plant populations, known as masting, is implicated in many ecological processes, but how it arises remains poorly understood. Flowering and pollination dynamics are hypothesized to provide the mechanistic link for the observed relationship between weather and population‐level seed production. We report the first experimental test of the phenological synchrony hypotheses as a driver of pollen limitation in mast seeding oaks (Quercus ilex). Higher flowering synchrony yielded greater pollination...