ORIGINAL ARTICLE: Leptin associations with age, weight, and sex among chimpanzees (Pan troglodytes)

Energetics of feeding, social behavior, and life history in non-human primates

Energy is a variable of key importance to a wide range of research in primate behavioral ecology, life history, and conservation. However, obtaining detailed data on variation in energetic condition, and its biological consequences, has been a considerable challenge. In the past 20years, tremendous strides have been made towards non-invasive methods for monitoring the physiology of animals in their natural environment. These methods provide detailed, individualized data about energetic condition, as well as energy allocations to growth, reproduction, and somatic health. In doing so, they add much-needed resolution by which to move beyond correlative studies to research programs that can discriminate causes from effects and disaggregate multiple correlated features of the social and physical environment. In this review, I describe the conceptual and methodological approaches for studying primate energetics. I then discuss the core questions about primate feeding ecology, social behavior, and life history that can benefit from physiological studies, highlighting the ways in which recent research has done so. Among these are studies that test, and often refute, common assumptions about how feeding ecology shapes primate biology, and those that reveal proximate associations between energetics and reproductive strategies.

Energetics of feeding, social behavior, and life history in non-human primates

Energy is a variable of key importance to a wide range of research in primate behavioral ecology, life history, and conservation. However, obtaining detailed data on variation in energetic condition, and its biological consequences, has been a considerable challenge. In the past 20years, tremendous strides have been made towards non-invasive methods for monitoring the physiology of animals in their natural environment. These methods provide detailed, individualized data about energetic condition, as well as energy allocations to growth, reproduction, and somatic health. In doing so, they add much-needed resolution by which to move beyond correlative studies to research programs that can discriminate causes from effects and disaggregate multiple correlated features of the social and physical environment. In this review, I describe the conceptual and methodological approaches for studying primate energetics. I then discuss the core questions about primate feeding ecology, social behavior, and life history that can benefit from physiological studies, highlighting the ways in which recent research has done so. Among these are studies that test, and often refute, common assumptions about how feeding ecology shapes primate biology, and those that reveal proximate associations between energetics and reproductive strategies.

Arboreal adaptations of body fat in wild toque macaques (Macaca sinica) and the evolution of adiposity in primates

There is a paucity of information on body composition and fat patterning in wild nonhuman primates. Dissected adipose tissue from wild toque macaques (Macaca sinica) (WTM), feeding on a natural diet, accounted for 2.1% of body weight. This was far less than fatness reported for nonhuman primates raised in captivity or for contemporary humans. In WTM, fatness increased with age and diet richness, but did not differ by sex. In WTM (none of which were obese) intra-abdominal fat filled first, and "excess" fat was stored peripherally in a ratio of about 6:1. Intermuscular fat was minimal (0.1%). The superficial paunch held <15% of subcutaneous fat weight in contrast to its much larger proportions in obese humans and captive monkeys where most added fat accumulates subcutaneously. With increasing total adiposity, accumulating fat shifted in its distribution among eight different main internal and peripheral deposit areas-consistent with maintaining body balance and a low center of gravity. The available data suggest that, in arboreal primates, adaptations for agile locomotion and terminal branch feeding set constraints on the quantity and distribution of fat. The absence of a higher percentage of body fat in females and neonates (as are typical of humans) suggests that arboreal adaptations preclude the development of fat-dependent, large-brained infants and the adipose-rich mothers needed to sustain them. The lifestyle and body composition of wild primates represent a more appropriate model for early human foragers than well-fed captive monkeys do.