![]() ![]() This arboreal heritage of primates has resulted in hands and feet that are adapted for brachiation, or climbing and swinging through trees. Characteristics of PrimatesĪll primate species possess adaptations for climbing trees, as they all descended from tree-dwellers. The characteristics and evolution of primates is of particular interest to us as it allows us to understand the evolution of our own species. They range in size from the mouse lemur at 30 grams (1 ounce) to the mountain gorilla at 200 kilograms (441 pounds). Non-human primates live primarily in the tropical or subtropical regions of South America, Africa, and Asia. Order Primates of class Mammalia includes lemurs, tarsiers, monkeys, apes, and humans. Explain why scientists are having difficulty determining the true lines of descent in hominids.Describe the derived features that distinguish primates from other animals.“There is growing evidence that the emergence of the genus Homo did not result from the emergence of entirely new behaviors but rather from the accentuation of traits already present in Australopithecus, including tool making and meat consumption”, says Jean-Jacques Hublin, director at the Max Planck Institute for Evolutionary Anthropology.By the end of this section, you will have completed the following objectives: ![]() These results support previously published archaeological evidence for stone tool use in australopiths and provide skeletal evidence that our early ancestors used human-like hand postures much earlier and more frequently than previously considered. “This new evidence changes our understanding of the behaviour of our early ancestors and, in particular, suggests that in some aspects they were more similar to humans than we previously thought”, says Matthew Skinner of the Max Planck Institute for Evolutionary Anthropology and the University of Kent. The research shows that Australopithecus africanus, a three to two million-year-old species from South Africa traditionally considered not to have engaged in habitual tool manufacture, has a human-like trabecular bone pattern in the bones of the thumb and palm (the metacarpals) consistent with forceful opposition of the thumb and fingers typically adopted during tool use. This unique human pattern is present in known non-arboreal and stone tool-making fossil human species, such as Neandertals. ![]() They found clear differences between humans, who have a unique ability for forceful precision gripping between thumb and fingers, and chimpanzees, who cannot adopt human-like postures. The researchers first examined the trabeculae of hand bones of humans and chimpanzees. “Over time these structures adapt in a way that enables them to handle the daily loads in the best way possible“, says Dieter Pahr of the Institute of Lightweight Design and Structural Biomechanics at the Vienna University of Technology where special computer algorithms for the analysis of the computer tomography images of the bones had been developed. Trabecular bone remodels quickly during life and can reflect the actual behaviour of individuals in their lifetime. Matthew Skinner and Tracy Kivell of the Max Planck Institute for Evolutionary Anthropology and the University of Kent used new techniques to reveal how fossil species were using their hands by examining the internal spongey structure of bone called trabeculae. However, it is unclear when these locomotory and manipulative transitions occurred. The distinctly human ability for forceful precision (e.g., when turning a key) and power “squeeze” gripping (e.g., when using a hammer) is linked to two key evolutionary transitions in hand use: a reduction in arboreal climbing and the manufacture and use of stone tools. ![]()
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