"The ability to recognize kin is crucial, because it allows animals to choose appropriate partners for coalitions, avoid mating with close relatives, and avoid killing their own offspring," co-author Jo Setchell explains. "Odor might be especially important because most chimpanzees live in dense forests where visibility is low, and because in chimpanzee societies, group members split up into subgroups that may not see each other for days," Henkel adds.įurthermore, the researchers found that chimpanzees sniffed longer at the odor the more closely related they were to the odor donor, providing the first evidence for odor-mediated kin recognition in non-human great apes. "Chimpanzees are highly territorial, and encounters between groups are mostly hostile - in fact, they sometimes kill individuals from other communities - so olfactory cues might help them to locate other animals and determine whether they are group members or strangers, enhancing their survival and leading to fitness benefits," says lead author Stefanie Henkel of the University of Leipzig and the Max Planck Institute for Evolutionary Anthropology. More importantly, they discriminated between the smell of group members and strangers, sniffing outgroup odors longer than ingroup odors. Chimpanzees sniffed longer at urine than at the control, suggesting they perceive the odor of other chimpanzees. All rights reserved.The scientists presented two groups of chimpanzees with urine from group members, strangers and an unscented control in aerated plexiglass boxes and videotaped their behavior. We do however find some evidence that shoulder configuration allows greater scapular elevation in chimpanzees during arboreal behaviors (e.g., vertical climbing).Ĭhimpanzee Electromyography Kinematic Kinetic Locomotion Vertical climbing.Ĭopyright © 2018 Elsevier Ltd.
Our data suggest there is little to no evidence supporting recent hypotheses that the African ape upper thorax and shoulder configuration is an adaptation for knuckle-walking, or more broadly, that knuckle-walking exists as an adaptation to absorb impact shock during terrestriality. Electromyographic results show that activity of the triceps brachii may facilitate energy absorption while serratus anterior likely functions to support the trunk, as in other primates. Ground reaction forces indicate that only a minority of strides in either chimpanzees or macaques have transient forces and, when present, these transient forces as well as loading rates are small. We found that the acromion is significantly more elevated in vertical climbing than during knuckle-walking, while dorsoventral ranges and magnitudes of motion were similar between gaits. We also investigated patterns of recruitment of select forelimb musculature (triceps brachii and serratus anterior) using previously collected data in chimpanzees to determine whether these muscles may function to absorb impact transient forces. We collected 3D kinematic data to quantify motion of the acromion and trunk during quadrupedalism and vertical climbing in chimpanzees as well as ground reaction forces to investigate the presence and magnitude of impact transient forces during terrestrial locomotion in chimpanzees and macaques.
Here we test several tenets of these hypotheses using kinematic and kinetic data from chimpanzees and macaques, and electromyographic data of shoulder muscle activity in chimpanzees. Recently it has been proposed that these traits are instead adaptations for knuckle-walking, and more broadly, that knuckle-walking itself is an adaptation for shock absorption during terrestriality. Great apes exhibit a suite of morphological traits of the shoulder and upper thorax that have traditionally been linked to orthograde arborealism.
0 kommentar(er)
