Final answer:
Primates are distinguished by adaptations for climbing such as rotating shoulder joints, opposable thumbs, and stereoscopic vision, along with larger brains and a trend toward upright posture. They are divided into prosimians and anthropoids, with comparative studies revealing behavioral and anatomical insights into the human species.
Step-by-step explanation:
Physical/Anatomical and Life History Traits Unique to the Order Primates
The Order Primates includes humans and is characterized by unique physical and anatomical features that distinguish its members from other mammals. These features are largely due to the primates' arboreal heritage, which has led to adaptations suited for life in the trees. For instance, primates possess hands and feet that are specialized for climbing and brachiation, such as having a rotating shoulder joint, widely separated big toes (except humans), and opposable thumbs for gripping branches. Stereoscopic vision enables primates to perceive depth and judge distances, crucial for moving among the trees. Primates also have a reduced reliance on the sense of smell with a greater emphasis on vision.
Primates generally have larger brains compared to other mammals, flattened nails instead of claws, and most primates typically bear one offspring per pregnancy. They also tend towards an upright body posture. Living primates are classified into prosimians, such as bush babies and lemurs, which are generally smaller and nocturnal, and anthropoids, which include monkeys, apes, and humans, with relatively larger brains. Understanding these traits provides significant insight into the behavioral variation among primates and what it means to be human.