Grasping limbs with opposable digits distinguish primates from other mammals. Bipedal locomotion and large brains evolved in the primate ancestors that led to humans, which facilitated the development of complex language and culture.
learning outcomes
You should be able to:
Summarize the diversity within the primates.
Articulate the relationship between bigger brains, smaller jaws, and neoteny.
Describe the differences between Old World and New World monkeys.
New World monkeys are all arboreal, and most have a long, prehensile tail that they use to grasp branches in climbing. Many Old World monkeys are more terrestrial, and they all lack a prehensile tail.
Explain how neoteny resulted in the development of humans with relatively large brains and small jaws.
Changes in a regulatory gene that affects skull development resulted in delayed somatic development in humans (neoteny). This led to the evolution of adult human skulls that are shaped more like those of juveniles (with relatively large brains and small jaws). Thus the human skull increased in size without changing as much in shape as occurs in our closest relatives, the chimpanzees.