Figure 4.23 Orangutans, the only great ape from Asia, are one of many living primate species. Others include lemurs, monkeys, gibbons, and human beings. (credit: Dawn Armfield/Wikimedia Commons, Public Domain)
Primates—including human beings—are characterized by a number of distinct physical features that distinguish them from other mammals. These include
- opposable thumbs and (in nonhuman primates) opposable big toes;
- the presence of five digits (fingers or toes) on the appendages;
- flat nails instead of curved claws;
- pads at the tips of the fingers made up of deposits of fat and nerves;
- reduced reliance on sense of smell and a relatively small snout;
- depth perception;
- binocular vision (being able to see one image with both eyes);
- a relatively slow reproductive rate;
- relatively large brain size; and
- postorbital bars (bony rings that completely surround the eyes).
Figure 4.24 The hands of this bonobo, including its opposable thumbs, look very similar to human hands. Opposable thumbs or toes are a primate trait shared by no other group of mammals. (credit: “Bonobo Plankendaal” by Marie van Dieren/flickr, CC BY 2.0)
The first four traits enhance dexterity and enable primates to use their hands and feet differently from other mammals. Other traits on this list represent a shift in emphasis among the sense organs between primates and other mammals. Primates are characterized by a greater emphasis on vision and a reduced reliance on smell relative to other mammals.
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The content of this course has been taken from the free Anthropology textbook by Openstax