Mammalian tooth wear research reveals contrasting patterns seemingly linked to diet: irregularly-pitted enamel surfaces, possibly from consuming hard seeds, vs. roughly-aligned linearly-grooved surfaces, associated with eating tough leaves. These patterns are important for assigning diet to fossils, including hominins. However, experiments establishing conditions necessary for such damage challenge this paradigm. Lucas et al. (2013) slid natural objects against enamel, concluding anything less hard than enamel would rub, not abrade, its surface (producing no immediate wear)....

Space use in mammals may be influenced not only by their primary foods, but also by localized sources of physiologically critical resources such as sodium-rich plants. We examined how sodium acquisition influences habitat use in mountain gorillas (Gorilla beringei) in Rwanda which have increased the amount of time they forage on community land outside of Volcanoes National Park (VNP), where eucalyptus (Eucalyptus spp.) tree bark is their most frequently eaten food. We measured sodium content...

Primates were traditionally thought to have a reduced sense of smell. Although there is now evidence that olfaction plays a greater role in primate social life than previously assumed, research on the sense of smell in non-human apes is scarce. Chimpanzees sniff the ground and vegetation on boundary patrols, but the function of this behaviour is unclear. Since chimpanzees are highly territorial and can kill individuals that do not belong to their own community, sniffing...

Researchers studying extant and extinct taxa are often interested in identifying the evolutionary processes that have lead to the morphological differences among the taxa. Ideally, one could distinguish the influences of neutral evolutionary processes (genetic drift, mutation) from natural selection, and in situations for which selection is implicated, identify the targets of selection. The directional selection gradient is an effective tool for investigating evolutionary process, because it can relate form (size and shape) differences between...

Kin recognition is a key ability which facilitates the acquisition of inclusive fitness benefits and enables optimal outbreeding. In primates, phenotype matching is considered particularly important for the recognition of patrilineal relatives, as information on paternity is unlikely to be available via social familiarity. Phenotypic cues to both paternal and maternal relatedness exist in the facial features of humans and other primates. However, theoretical models suggest that in systems with parentage uncertainty it may be...

Background: A median, segmented, annelid nerve cord has repeatedly been compared to the arthropod and vertebrate nerve cords and became the most used textbook representation of the annelid nervous system. Recent phylogenomic analyses, however, challenge the hypothesis that a subepidermal rope-ladder-like ventral nerve cord (VNC) composed of a paired serial chain of ganglia and somata-free connectives represents either a plesiomorphic or a typical condition in annelids. Results: Using a comparative approach by combining phylogenomic analyses...

Living in permanent social groups forces animals to make decisions about when, how and with whom to interact, requiring decisions to be made that integrate multiple sources of information. Changing social environments can influence this decision-making process by constraining choice or altering the likelihood of a positive outcome. Here, we conceptualised grooming as a choice situation where an individual chooses one of a number of potential partners. Studying two wild populations of sympatric primate species,...

Three adaptive hypotheses have been forwarded to explain the distinctive Neanderthal face: 1) an improved ability to accommodate high anterior bite forces, 2) more effective conditioning of cold and/or dry air, and, 3) adaptation to facilitate greater ventilatory demands. We test these hypotheses using three-dimensional models of Neanderthals, modern humans, and a close outgroup (H. heidelbergensis), applying finite element analysis (FEA) and computational fluid dynamics (CFD). This is the most comprehensive application of either approach...

1. Distance sampling (DS) is a widely-used framework for estimating animal abundance. DS models assume that observations of distances to animals are independent. Non-independent observations introduce overdispersion, causing model selection criteria such as AIC or AICc to favour overly complex models, with adverse effects on accuracy and precision. 2. We describe, and evaluate via simulation and with real data, estimators of an overdispersion factor (c ̂), and associated adjusted model selection criteria (QAIC) for use...

Data ON DAILY TRAVEL, ACTIVITY BUDGETS AND ENERGY INTAKEDATA FOR DAILY TRAVEL DISTANCES, ACTIVITY BUDGET (FOR TIME SPENT FEEDING AND TRAVELING), AND FOOD SITES (FOR ENERGY INTAKE AND INDIVIDUAL TRAVEL).Data for repository.xls

Vocal signals often play an important role in synchronizing the activities of group members, coordinating decisions about when and where to travel, and facilitating social interactions in which there are potential conflicts of interest. In chacma baboons, Papio ursinus, low amplitude grunts facilitate nonaggressive social interactions and reconcile conflicts. Grunts seem to function as signals of benign intent and reduce uncertainty about the signaler's subsequent behavior. Here, we replicate and extend these findings in another...

Humans share an extraordinary degree of sociality with other primates, calling for comparative work into the evolutionary drivers of the variation in social engagement observed between species. Of particular interest is the contrast between the chimpanzee (Pan troglodytes) and bonobo (Pan paniscus), the latter exhibiting increased female gregariousness, more tolerant relationships, and elaborate behavioral adaptations for conflict resolution. Here we test predictions from three socio-ecological hypotheses regarding the evolution of these traits using data on...