title: Monkeys spontaneously discriminate their unfamiliar paternal kin under natural conditions using facial cues.
abstract: Kin recognition can enhance inclusive fitness via nepotism and optimal outbreeding. Mechanisms allowing recognition of patrilineal relatives are of particular interest in species in which females mate promiscuously, leading to paternity uncertainty. Humans are known to detect facial similarities between kin in the faces of third parties, and there is some evidence for continuity of this ability in nonhuman primates . However, no study has yet shown that this propensity translates into an ability to detect one's own relatives, one of the key prerequisites for gaining fitness benefits. Here we report a field experiment demonstrating that free-ranging rhesus macaques (Macaca mulatta) spontaneously discriminate between facial images of their paternal half-siblings and unrelated individuals, when both animals are unfamiliar to the tested individual. Specifically, subjects systematically biased their inspection time toward nonkin when the animals pictured were of their own sex (potential threats), relative to when they were of the opposite sex (potential mates). Our results provide strong evidence for visual phenotype matching and the first demonstration in any primate that individuals can spontaneously detect their own paternal relatives on the basis of facial cues under natural conditions.
authors: Junior Research Group of Primate Kin Selection, Department of Primatology, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany; Behavioural Ecology Research Group, Institute of Biology, University of Leipzig, 04103 Leipzig, Germany. Electronic address: dana.pfefferle@duke.edu.
authors: Dana
authors: D
authors: Pfefferle
authors: Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany; Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway.
authors: Anahita J N
authors: AJ
authors: Kazem
authors: Cognitive Neuroscience Laboratory, German Primate Center, 37077 Göttingen, Germany.
authors: Ralf R
authors: RR
authors: Brockhausen
authors: Junior Research Group of Primate Kin Selection, Department of Primatology, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany; Behavioural Ecology Research Group, Institute of Biology, University of Leipzig, 04103 Leipzig, Germany; Caribbean Primate Research Center-Cayo Santiago, University of Puerto Rico, Punta Santiago, PR 00741, USA.
authors: Angelina V
authors: AV
authors: Ruiz-Lambides
authors: Junior Research Group of Primate Kin Selection, Department of Primatology, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany; Behavioural Ecology Research Group, Institute of Biology, University of Leipzig, 04103 Leipzig, Germany.
authors: Anja
authors: A
authors: Widdig
mesh_terms: D000818:Animals; D003463:Cues; D005145:Face / Q000033:anatomy & histology; D005260:Female; D008253:Macaca mulatta / Q000502:physiology* / Q000523:psychology; D008297:Male; D021641:Recognition, Psychology; D035781:Siblings; D014796:Visual Perception