Behavioral, Ecological, and Evolutionary Aspects of Meat-Eating by Sumatran Orangutans (Pongo abelii)

Abstract

Meat-eating is an important aspect of human evolution, but how meat became a substantial component of the human diet is still poorly understood. Meat-eating in our closest relatives, the great apes, may provide insight into the emergence of this trait, but most existing data are for chimpanzees. We report 3 rare cases of meat-eating of slow lorises, Nycticebus coucang, by 1 Sumatran orangutan mother–infant dyad in Ketambe, Indonesia, to examine how orangutans find slow lorises and share meat. We combine these 3 cases with 2 previous ones to test the hypothesis that slow loris captures by orangutans are seasonal and dependent on fruit availability. We also provide the first (to our knowledge) quantitative data and high-definition video recordings of meat chewing rates by great apes, which we use to estimate the minimum time necessary for a female Australopithecus africanus to reach its daily energy requirements when feeding partially on raw meat. Captures seemed to be opportunistic but orangutans may have used olfactory cues to detect the prey. The mother often rejected meat sharing requests and only the infant initiated meat sharing. Slow loris captures occurred only during low ripe fruit availability, suggesting that meat may represent a filler fallback food for orangutans. Orangutans ate meat more than twice as slowly as chimpanzees (Pan troglodytes), suggesting that group living may function as a meat intake accelerator in hominoids. Using orangutan data as a model, time spent chewing per day would not require an excessive amount of time for our social ancestors (australopithecines and hominids), as long as meat represented no more than a quarter of their diet.Electronic supplementary materialThe online version of this article (doi:10.1007/s10764-011-9574-z) contains supplementary material, which is available to authorized users.

Broad-scale phylogenomics provides insights into retrovirus–host evolution

“…2), which is the taxonomic group containing the highest overall representation of gamma-ERVs. It may be possible that these euarchontoglire hosts are not strictly vegetarian because recent studies suggest that several of these taxa do occasionally eat meat (22,23), given that even rare carnivorous acts may be sufficient to expose hosts to retroviral infection. Other life-history and ecological traits may also influence susceptibility to infection by gammaretroviruses.…”

Reproductive state and rank influence patterns of meat consumption in wild female chimpanzees (Pan troglodytes schweinfurthii)

“…Given the nutritional value of faunivory, it is unsurprising that populations of all great ape clades habitually consume vertebrates (chimpanzees: Newton-Fisher, 2014; bonobos [ Pan paniscus ]: Surbeck and Hohmann, 2008, 2009; orangutans [ Pongo spp. ]: Hardus et al, 2012) and/or invertebrates (chimpanzees: Goodall, 1968; McGrew, 1992; bonobos: Badrian et al, 1981; Badrian and Melenky, 1984; orangutans: van Schaik et al, 1996; Fox et al, 2004; gorillas [ Gorilla spp. ]: Tutin and Fernandez, 1992; Ganas and Robbins, 2004).…”

Limits of Spatial Vision in Sumatran Orangutans (Pongo abelii)

“…In these conditions orangutans must find food, which can be difficult to identify and requires extensive travel to locate (Rijksen, 1978). The majority of the Sumatran orangutan diet is fruit, but they also consume bark, leaves, pith, flowers, sap, roots, seeds, honey, fungi, mineral-rich soil, eggs, invertebrates, and meat, and some of these foods require precise manipulation and tool use (Hardus et al, 2012;Rijksen, 1978;van Schaik, 2004;Wich et al, 2004). Like other primates, vision is their dominant sense, and thus relied on by orangutans to locate and identify these foods (Gilad, Wiebe, Przeworski, Lancet, & Pääbo, 2004;Matsuno & Fujita, 2009;Schrauf & Call, 2009).…”