Primate Ecology

The social brain hypothesis posits that social complexity is the primary driver of primate cognitive complexity, and that social pressures ultimately led to the evolution of the large human brain. Although this idea has been supported by studies indicating positive relationships between relative brain and/or neocortex size and group size, reported effects of different social and mating systems are highly conflicting. Here, we use a much larger sample of primates, more recent phylogenies, and updated statistical techniques, to show that brain size is predicted by diet, rather than multiple measures of sociality, after controlling for body size and phylogeny. Specifically, frugivores exhibit larger brains than folivores. Our results call into question the current emphasis on social rather than ecological explanations for the evolution of large brains in primates and evoke a range of ecological and developmental hypotheses centred on frugivory, including spatial information storage, ex...

Comment les Grecs et les Romains ont-ils représenté le singe, cet animal qui, dans la culture occidentale des deux derniers siècles, a surtout incarné de nouvelles possibilités de repenser la relation entre les hommes et les non-humains ? En dehors du paradigme évolutionniste élaboré par Darwin et repris par la biologie post-darwinienne, sans les données de la génétique et le dispositif disciplinaire de la primatologie, les textes anciens ont construit d'autres représentations culturelles du singe sans le concevoir comme un cousin ou un parent proche avec lequel nous aurions un ancêtre commun.
À travers une analyse philologique rigoureuse des textes grecs et romains, des traités savants de la zoologie et la médecine grecques aux élaborations symboliquement plus complexes du théâtre comique ou de la fable, cette étude propose une analyse approfondie de la représentation discursive des primates non humains dans la culture antique depuis Sémonide d’Amorgos à Élien de Préneste.
Des questions essentielles pour la compréhension des cultures anciennes - de l'anthropomorphisme des animaux au débat sur l'intelligence des vivants en passant par les élaborations autour de l'importante catégorie de la mimésis – seront abordées selon une approche d’anthropologie historique. Les relations interspécifiques, la représentation de l'altérité géographique et culturelle, les jugements de valeur exprimés sur les groupes minoritaires et marginaux de la société ancienne seront traités à travers la perspective transversale donnée par l'analyse d'une partie spécifique de l'encyclopédie culturelle ancienne, à savoir le singe des Anciens.

Los dientes de los vertebrados, y especialmente de los mamíferos, muestran una gran diversidad de formas como resultado de las adaptaciones ecológicas y alimentarias de las especies en función del hábitat y las condiciones ecológicas. La anatomía dental es de gran utilidad para definir especies y caracterizar poblaciones, y se ha utilizado extensamente para definir nuevos taxones y establecer relaciones filogenéticas. Nuestras investigaciones sobre la evolución morfológica de la dentición de los homininos han puesto de relieve la importancia de los dientes en la caracterización de las adaptaciones ecológicas de nuestros antepasados. El presente trabajo es el primero de una serie de tres trabajos que nos planteamos sobre la importancia de las características anatómicas en la interpretación de la evolución de nuestro linaje. En él se describen los principales eventos evolutivos que dieron origen a los dientes y su diversificación.

Palabras clave
dientes, anatomía, evolución, mamíferos, primates, homininos

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Origin and evolution of teeth: from the primitive chordates to modern humans

Abstract
The teeth of vertebrates, especially mammals, show a great diversity of forms as a result of ecological and dietary adaptations in relation to habitat preferences and ecological conditions. The dental anatomy is useful to define and characterize populations and species, and has been used extensively to define new taxa, and
phylogenetic relationships among groups. Our research on the morphological evolution of the hominin dentition has highlighted the importance of the teeth in the characterization of the diet and the ecological adaptations of our ancestors. This study is the first in a series of three papers in which we consider the importance of
the dental anatomical features in the interpretation of the evolution of our lineage. It describes the major evolutionary events that gave rise to the teeth and their diversification. In subsequent works we will analyze in greater detail the diversification of the teeth of mammals and primates.

Key words
teeth, anatomy, evolution, mammals, primates, hominins

Bushmeat hunting is among the principal threats to larger-bodied vertebrate species, such as primates, in central Africa. However, species vary in their response to differing levels of hunting intensity, making it difficult to not only quantify the effect hunting has on wild populations, but also to plan for effective conservation interventions. In order to investigate the impact of hunting on primates on Bioko Island, Equatorial Guinea, we collected data on primate abundance and hunting intensity across three areas in the Gran Caldera Scientific Reserve (GCSR) via reconnaissance surveys. We assessed how the relative abundance and proportional representation of Bioko's seven diurnal primate species varied among the different sites and in relation to hunting intensity. Overall primate species richness and abundance were highest in areas where gun hunting was minimal, but both measures declined with increasing evidence of gun hunting. Two species of primates, Cercopithecus erythrotis and Cercopithecus nictitans, were relatively tolerant of heavy hunting, but all other species were considered vulnerable. Procolobus pennantii, a species endemic to Bioko, exhibited the highest vulnerability, and its range appears restricted to a very limited area in the southwest of the GCSR. Our analyses indicate that hunting on Bioko is a strong contributor to current patterns of primate abundance and diversity, and suggest that hunting may be driving Bioko's most threatened primates (e.g., P. pennantii) towards extinction. These results highlight the need for rapid intervention on Bioko in order to safeguard the future of its unique primates.

Many studies highlight the correlation between social ties and fitness, yet often cannot reveal how ties influence fitness. This review is aimed to facilitate the formulation and testing of hypotheses in this area on non-human primates. I outline fitness-relevant measures of social ties and 6 potential pathways from ties to fitness. Pathways include communal care; group level cooperation for resources ; monopolizing resources within groups; attaining social status; reducing risk and allostatic load; and developing behavioural competence. Hypotheses for further evaluation include (1) fitness increases sociality, not vice versa; (2) early life experience influences both ties and fitness, (3) ties are actually costly; (4) short term costs of ties are outweighed by long term benefits. With the advance of theoretical and methodological approaches to evaluate the costs and benefits of social ties, and monitor them at multi-generational field sites, primate behavioural ecologists are poised to test several of these hypotheses.

Conservation benefits from understanding how adaptability and threat interact to determine a taxon's vulnerability. Recognizing how interactions with humans have shaped taxa such as the critically endangered orangutan (Pongo spp.) offers insights into this relationship. Orangutans are viewed as icons of wild nature, and most efforts to prevent their extinction have focused on protecting minimally disturbed habitat, with limited success. We synthesize fossil, archeological, genetic, and behavioral evidence to demonstrate that at least 70,000 years of human influence have shaped orangutan distribution, abundance, and ecology and will likely continue to do so in the future. Our findings indicate that orangutans are vulnerable to hunting but appear flexible in response to some other human activities. This highlights the need for a multifaceted, landscape-level approach to orangutan conservation that leverages sound policy and cooperation among government, private sector, and community stake-holders to prevent hunting, mitigate human-orangutan conflict, and preserve and reconnect remaining natural forests. Broad cooperation can be encouraged through incentives and strategies that focus on the common interests and concerns of different stakeholders. Orangutans provide an illustrative example of how acknowledging the long and pervasive influence of humans can improve strategies to preserve biodiversity in the Anthropocene.

Discoverers of the hominid naledi fossils (300-250 ka, Gauteng, southern Africa, first described in 2015) anthropocentrically assume that naledi (1) belonged to the genus Homo, (2) buried their dead in caves, (3) were tool makers, (4) ran over African plains. Comparative anatomy shows these assumptions to be wrong, and suggests that naledi (1) generally resembled bonobos and belonged to the genus Pan or Australopithecus, (2) fossilized in a natural way, (3) were no better tool makers than extant chimpanzees are, (4) spent an important part of their day wading bipedally in forest swamps or wetlands, in search for wetland foods, possibly waterlilies or other aquatic herbaceous vegetation (AHV, possibly containing small snails), like bonobos and lowland gorillas still do but more frequently.

The Silvery-brown Tamarin, Saguinus leucopus, is a primate species from the Callitrichidae family, endemic to Colombia, and that has very little ecological information. Here we report on a new dietary component for the species from Departamento de Caldas, Colombia, been the first record of S. leucopus predating an amphibian species (Phyllomedusa venusta). Despite some records exist about tamarin predation on amphibians, this is the first for this endemic species, and it is probably related with its foraging type. This record represents a noteworthy record and contributes to the knowledge of the natural history of this species. Key words: Andes, Callitrichidae, Colombia, Diet, Primates, Predation.Palabras clave: Andes, Callitrichidae, Colombia, Depredación, Dieta, Primates

This study reports group size, home range size, daily path lengths, seasonal effects on ranging behavior, and qualitative information on diet for a population of hamadryas baboons inhabiting the lowlands of the northern Rift Valley in central Ethiopia. The minimum home range size and daily path length for this population are similar to those reported for other populations of hamadryas in Ethiopia and Saudi Arabia. Group sizes at Filoha, however, are much larger than those in most other hamadryas populations for which published data are available. The large group sizes in this area may be related to the abundance of one food resource in particular, doum palm nuts. Overall, this study suggests that hamadryas may be more flexible in some aspects of their behavioral ecology (e.g., group size) than in others (e.g., ranging behavior).

Jatna's Tarsier Tarsius supriatnai Shekelle, Groves, Maryanto et Mittermeier, 2017 is a species of primitive primates described very recently from the western part of the Gorontalo Province in North Sulawesi (Shekelle et al. 2017). The main aim of the present study is to identify correlations between forest degradation and conversion and population densities of Jatna’s Tarsier in a typical forest edge to agricultural land transition area in Popayato Paguat landscape and provide ecological data about the species and its spatial distribution. The results show that Tarsius supriatnai is not entirely restricted to the secondary forest. As long as small particular remnants of natural vegetation remain in the landscape, tarsiers are found be able to persist, but their population densities are considerably lower. Average population densities on agricultural-agroforest area (1.22 individuals/ha) differ significantly from those within the secondary rainforest (5.37 individuals/ha). Moreover, average population densities at the study plots undergoing forest conversion (1.05 individuals/ha) differ significantly from those unaffected (5.65 individuals/ha) by rainforest degradation (4.07 individuals/ha). Regarding to the IUCN Red List assessment guidelines, we confirm the criterion "VU Vulnerable" for Tarsius supriatnai based on the results of the present study.

The survival of the Tana River mangabey (Cercocebus galeritus) is threatened primarily by habitat fragmentation and loss due to pressure from human activities. However, the effects of such anthropogenic disturbance on the species' behavioral ecology are poorly understood. This study aimed to identify the anthropogenic activities and their impacts on mangabey behavior in Mchelelo and Mkomani forest patches in the Tana River Primate National Reserve. We hypothesized that Mkomani would experience higher levels of anthropogenic activities compared to Mchelelo due to its proximity to human settlements. Because detrimental human activities-such as tree cutting, palm wine tapping, and palm leaf harvesting-alter the forest habitat's cover, density, and distribution of important mangabey plant foods, we predicted that the species' behavior will show differences between the two sites due to varying levels of these human activities. We used quadrat and focal animal sampling methods to collect data on anthropogenic activities and to score mangabey behavior, respectively. Overall, tree cutting was the dominant human disturbance, followed by palm leaf harvesting and fire. Tree cutting and palm leaf harvesting were both higher in Mkomani compared to Mchelelo, respectively. Palm wine tapping was recorded exclusively in Mchelelo, while fire burning occurred only in Mkomani. The most exploited and important plant foods for the mangabeys were Phoenix reclinata, Polysphaeria multiflora, Lecaniodiscus fraxinifolius, and Thespesia danis. The group in Mkomani forest spent more time feeding and engaging in social interactions compared to that in Mchelelo. Our findings suggest that high exploitation of mangabey plant foods correspond with increased time spent feeding and in social interaction. Our findings are critical for informing the management and conservation of the Cercocebus galeritus and their habitat-especially in efforts to mitigate the detrimental anthropogenic activities in the lower Tana River forest patches.

A good book review provides documentation for its evaluations, especially when they are either very positive or very negative. A good review is also faithful to what the author has written and bases criticisms or praise on accurate paraphrasing or quotes from the book. This review by Thompson fails on both accounts. Critical comments are not documented and the review is based on what Thompson imagines Read to have written, not what Read actually wrote.

For gregarious species, individuals must maintain cohesion while minimizing the costs of coordinated travel. Leaders of group movements potentially influence energy expenditure, energy intake, and predation risk for individuals in the group, which can have important fitness consequences. Models of pair-living species predict that energetic asymmetries lead to an emergent leader, with those in greater need leading. We investigated sex differences in leadership in pairs of red-bellied lemurs, Eulemur rubriventer, a monomorphic species with bisexual dispersal and no discernible hierarchy, to determine whether higher energetic requirements by adult females lead to female leadership. We collected leadership data in Ranomafana National Park, Madagascar on six groups of habituated E. rubriventer for 13 consecutive months between 2004–2005. To determine whether females led group movements more than males, we examined the difference in leadership frequencies of progressions in adult males and adult females within each group (n = 1,346 progressions). We further investigated the behavioral context (i.e. travel followed by feeding or not) and seasonal contexts (fruit availability, reproduction) of leadership. Group leadership was distributed, with different individuals leading the group at different times. However, females led significantly more than males, a pattern which was consistent in both feeding and non-feeding contexts and throughout all fruiting seasons and reproductive stages. While disparities in energetic status among the sexes may impact leadership in this species, leadership did not differ with changes in food availability or reproductive stage, and thus we were unable to determine whether female leadership might be related to changes in energetic status. Females may have higher energetic needs than males at all times, not merely seasonally, or female leadership may be unrelated to immediate energetic need. Rather, female leadership may be a legacy of female dominance not currently expressed in other contexts. Am. J. Primatol. 74:591–601, 2012. © 2012 Wiley Periodicals, Inc.

The adaptive origins of primates and anthropoid primates are topics of enduring interest to biological anthropologists. A convention in these discussions is to treat the light environment as binary-night is dark, day is light-and to impute corresponding selective pressure on the visual systems and behaviors of primates. In consequence, debate has tended to focus on whether a given trait can be interpreted as evidence of nocturnal or diurnal behavior in the primate fossil record. Such classification elides the variability in light, or the ways that primates internalize light in their environments. Here, we explore the liminality of light by focusing on what it is, its many sources, and its flux under natural conditions. We conclude by focusing on the intensity and spectral properties of twilight, and we review the mounting evidence of its importance as a cue that determines the onset or offset of primate activities as well as the entrainment of circadian rhythms.

We compared the feeding ecology of the Hali–Hali community of bonobos (Pan paniscus) at Kokolopori, a new field site in the Democratic Republic of the Congo, between two periods 5 months apart. During the first study period (SP1), bonobos relied heavily on the dry seeds of Guibourtia (Caesalpiniaceae), mostly eaten from the ground. The second period (SP2) was characterized by high consumption of ripe tree fruit. Terrestrial herbaceous vegetation (THV) contributed little to the diet in either study period. The low amount of ripe fruit and the high reliance on seeds in the diet during SP1 were associated with high cortisol production and low levels of urinary C-peptide in females, suggesting nutritional stress. However, female gregariousness was not constrained during the fruit-poor period, probably because high seed abundance on the ground ameliorated scramble feeding competition. This is the first description of extensive seed predation by bonobos. It suggests that bonobo feeding ecology may be more similar to that of chimpanzees than previously recognized.

Regulation of body temperature poses significant problems for organisms that inhabit environments with extreme and seasonally fluctuating ambient temperatures. To help alleviate the energetic costs of autonomic responses, these organisms often thermoregulate through behavioral mechanisms. Among primates, lemurs in Madagascar experience uncharacteristically seasonal and unpredictable climates relative to other primate-rich regions. Malagasy primates are physiologically flexible, but different species use different mechanisms to influence their body temperatures. Lemur catta, the ring-tailed lemur, experiences particularly acute diurnal temperature fluctuations in its mostly open-canopy habitat in south and southwest Madagascar. Ring-tailed lemurs are also atypical among lemurs in that they appear to use both sun basking postures and huddling to maintain body temperature when ambient temperatures are cold. To our knowledge, however, no one has systematically tested whether these behaviors function in thermoregulation. We present evidence that ring-tailed lemurs use these postures as behavioral thermoregulation strategies, and that different environmental variables are associated with the use of each posture. Major predictors of sunning included ambient temperature, time of day, and season. Specifically, L. catta consistently assumed sunning postures early after daybreak when ambient temperatures were <13°C, and ceased sunning around 10:00a.m., after ambient temperatures approached 26°C. Sunning occurred more often during austral winter months. Huddling was associated with time of day, but not with ambient temperature or season. We conclude that L. catta tend to sun, rather than huddle, under cold weather conditions when sunning is possible. However, both sunning and huddling are important behavioral adaptations of L. catta that augment chemical thermoregulation and the absence of a dynamic, insulating pelage. Sunning and huddling help to account for the great ecological flexibility of the species, but these adaptations may be insufficient in the face of future changes in protective vegetation and temperature.

Molar occlusal microwear texture and anisotropy analyses of 3 Australopithecus anamensis fossil specimens have shown complexity values similar to those of Au.afarensis,indicating that neither of these hominin species had a diet dominated by hard food. However, many researchers have suggested that these were some of the earliest hominins to have such diets. Here we examine buccal microwear patterns of 5 Au. anamensis, 26 Au. afarensis, 48 Hominoidea and 80 Cercopithecoidea primate specimens for independent evidence of dietary adaptations of Au. anamensis. The buccal microwear results obtained suggest that the diet of Au.anamensis relied heavily on hard, brittle food, at least seasonally. This is similar to the diet of the extant Cercopithecoidea primates, including Papio anubis and Chlorocebus aethiops, both of which live in wooded, seasonal savannah environments and have diets that include fruit and grasses, but also underground storage organs (USOs), such as corms or blades, as well as leaves and seeds, and also Mandrillus and Cercocebus, from forested environments with frugivorous-granivorous diets. Furthermore, the buccal microwear patterns of Au.anamensis and Au.afarensis clearly differed –in clear contrast to occlusal enamel texture observations–, which support previous dietary interpretations based on both anatomical and palaeocological reconstructions.

Keywords: hominin, diet, feeding ecology, buccal microwear, fallback food, Australopithecus anamensis

New World monkeys are a diverse primate group and a model for understanding hearing in mammals. However, comparable audiograms do not exist for the larger monkeys, making it difficult to test the hypothesized relationship between interaural distance and high-frequency hearing limit (i.e., the allometric model). Here, the auditory brainstem response (ABR) method is used to assess auditory sensitivity in four tufted capuchins (Sapajus apella), a large monkey with a large interaural distance. A primate-typical four-peak pattern in the ABR waveforms was found with peak latencies from ca. 2 to 12 ms after stimulus onset. Response amplitude decreased linearly with decreasing stimulus level (mean r2 = 0.93, standard deviation 0.14). Individual variation in each threshold was moderate (mean +/- 7 dB). The 10-dB bandwidth of enhanced sensitivity was 2-16 kHz—a range comparable to smaller monkeys and congruent with the bandwidth of their vocal repertoire. In accord with the general principles of the allometric model, the 60-dB high-frequency limit of S. apella (26 kHz) is lower than those of smaller-headed monkeys; however, it is substantially lower than 44.7 kHz, the value predicted by the allometric model. These findings and other exceptions to the allometric model warrant cautious application and further investigation of other potential selective factors.

Plants producing toxic plant secondary metabolites (PSMs) deter folivores from feeding on them. Animals that can cope with noxious PSMs have a niche with a competitive advantage over other species. However, the ability to cope with toxic PSMs incurs the costs of detoxification. To assess possible compensations for the ingestion of toxic PSMs, we compare the chemical quality of plants consumed by bamboo lemurs (genera Hapalemur and Prolemur; strepsirrhine primates of Madagascar) in areas with and without bamboo. Some bamboo lemurs consume bamboo containing concentrations of cyanogenic substances 10–50 times above the average lethal dosage for mammals, and we postulate that animals consuming cyano-genic substances need supplementary protein or readily available energy for detoxifi-cation. We compared the chemical composition of food consumed by three species of bamboo lemurs that feed mainly (>80% of their time) on bamboo in the evergreen rainforest of Ranomafana (Madagascar) with published data of the diets of bamboo lemurs at two sites without highly cyanogenic plants (reed beds of Lac Alaotra and the evergreen littoral forest of Mandena) and with food of sympatric folivorous lemur species that do not feed on bamboo. Lemurs feeding on bamboo consumed up to twice as much protein as bamboo lemurs in areas without bamboo and sympatric lemur species that feed on leaves of trees. Concentrations of nonstructural carbohydrates (a source of energy) showed the opposite trend. This result supports the hypothesis that feeding on cyanogenic plants is linked to high protein intake, either as a source of protein or for sulfur-containing amino acids that can be used for detoxification. Owing to the high protein concentrations in bamboo, however, we cannot distinguish between the hypothesis that lemurs that eat bamboo target additional food items with higher
protein from the hypothesis that lemurs feeding on bamboo unavoidably obtain higher concentrations of protein than animals feeding on leaves of trees, without an added nutritional benefit.