Final answer:
Primates show several characteristics that demonstrate an adaptation to an arboreal lifestyle, such as small front teeth, an upright posture, increased dexterity of the hands, and larger brain size. They also have hands and feet adapted for climbing and brachiation, including stereoscopic vision, a rotating shoulder joint, and widely separated big toes and thumbs. These adaptations help primates grasp onto branches and navigate their arboreal habitat.
Step-by-step explanation:
Primates, including humans, show several characteristics that demonstrate an adaptation to an arboreal lifestyle. These adaptations include small front teeth (canines and incisors) and very large molars relative to other primate species, an upright posture resulting in bipedalism, shortening of the arms relative to the legs, increased dexterity of the hands, an increase in brain size (especially in the frontal lobes), and a decrease in bone mass of the skull and face.
Life in the trees requires excellent vision and depth perception, so primates have adapted with stereoscopic vision. They also have hands and feet adapted for climbing and brachiation, such as a rotating shoulder joint, a big toe that is widely separated from the other toes, and thumbs that are sufficiently separated from the fingers for gripping branches. These adaptations help primates grasp onto branches and move through the trees safely. Other characteristics of primates include larger brains, modified claws into flattened nails, typically one offspring per pregnancy, and a trend toward holding the body upright.
Overall, primates exhibit several traits that show their adaptation to an arboreal lifestyle, allowing them to thrive in the trees and use their environment effectively.