The biomechanical and adaptive significance of variation in craniodental and mandibular morphology in fossil hominins is not always clear, at least in part because of a poor understanding of how different feeding behaviors impact feeding system design (form–function relationships). While laboratory studies suggest that ingestive behaviors produce variable loading, stress, and strain regimes in the cranium and mandible, understanding the relative importance of these behaviors for feeding system design requires data on their use in wild populations. Here we assess the frequencies and durations of manual, ingestive, and masticatory behaviors from more than 1400 observations of feeding behaviors video-recorded in a wild population of bearded capuchins (Sapajus libidinosus) at Fazenda Boa Vista in Piauí, Brazil. Our results suggest that ingestive behaviors in wild Sapajus libidinosus were used for a range of food material properties and typically performed using the anterior dentition. Coupled with previous laboratory work indicating that ingestive behaviors are associated with higher mandibular strain magnitudes than mastication, these results suggest that ingestive behaviors may play an important role in craniodental and mandibular design in capuchins and may be reflected in robust adaptations in fossil hominins.
Robust capuchin monkeys (Sapajus) are known for processing mechanically challenging foods, having morphological adaptations to do so. However, several populations go beyond body limitations by using stone tools to expand their food range. Those populations use stones in a variety of ways, goals, and with different frequencies. Stone tool size correlates with the food’s resistance within some populations. However, we have no detailed comparisons to identify if this correlation is the same across populations. This study described and compared stone raw material availability, food’s physical properties (hardness and elasticity), and stone tool weight in three populations of bearded capuchin monkeys (Sapajus libidinosus), including a newly described site (Chapada dos Veadeiros National Park, CVNP). The differences we observed regarding stone tool weight selection among sites were not correlated to the food’s physical properties we analyzed. Lithic resource availability could partly explain some differences in the stone tools used. However, the tool weight differences are larger than the raw material variance across sites, meaning some distinctions are possible behavioral traditions, such as the same fruit (Hymenaea) being processed with bigger than needed tools in CVNP than in the other two sites. Capuchin monkey behavioral variability in stone tool use can be caused by several interacting factors, from ecological to cultural.
Objectives: Foods that are geometrically and mechanically challenging to eat have been associated with specializations in feeding behavior and craniodental morphology across primates, and many of these foods are embedded, requiring a variety of positional behaviors during feeding. However, variation in positional behaviors in response to food properties is not well understood. Here, we examine differences in feeding postural behaviors across feeding events in relation to substrate and food geometric and material properties in a species of extractive foragers, bearded capuchins (Sapajus libidinosus).
Methods and materials:We coded over 1400 co-occurring postural and feeding behaviors, their durations, and relative sizes of substrate and food from videos recorded at Fazenda Boa Vista in Gilbués, Piauí, Brazil. Food material properties were measured from foods collected at the time of the video recordings.Results: Our results suggest that bearded capuchin feeding postures significantly differ across the feeding sequence, with substrate size, and between foods of high and low toughness and elastic modulus. Feeding postures were less variable for highly
Objectives: Capuchin monkeys (Cebus spp. and Sapajus spp.) routinely extract food resources that are embedded in protective matrices. Features such as relative brain size, manual dexterity, and-in the case of Sapajus spp.-a robust feeding system are considered adaptations for accessing embedded foods. Compared with adults, juvenile capuchins exhibit reduced food processing efficiency when processing embedded foods. Although this reduced efficiency has been attributed to inexperience or lack of strength when processing embedded foods, little is known about how food material properties (FMPs) relate to age-related changes in feeding efficiency.
Materials and methods:We used data collected from three groups of Sapajus libidinosus to test relationships between feeding efficiency and FMP variation when processing embedded and nonembedded foods. Feeding efficiency was defined in three ways: (i) duration, (ii) frequency, and (iii) variation in sequence of food processing behaviors.Results: We found limited support for an effect of FMPs and age on feeding sequence durations or on processing behavior frequency. Number of unique behavioral patterns was negatively correlated with age. Embedded foods elicited longer
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