12 6 Primate Evolution How did modern humans

12. 6 Primate Evolution How did modern humans evolve?

12. 6 Primate Evolution KEY CONCEPT Humans appeared late in Earth’s history.

12. 6 Primate Evolution Humans share a common ancestor with other primates. • Common ancestor of all primates probably arose before the mass extinction that ended the Cretaceous Period. • Primates are mammals with flexible hands and feet, forward-looking eyes and enlarged brains.

12. 6 Primate Evolution • Primates evolved into prosimians and anthropoids. – Prosimians are the oldest living primates. – They are mostly small and nocturnal. (lemurs) These are the tarsiers. Their physical appearance has changed little since their appearance 40 MYA.

12. 6 Primate Evolution – Anthropoids are humanlike primates. – They are subdivided into the New World monkeys, Old World monkeys, and hominoids.

12. 6 Primate Evolution – New world monkeys are native to the Americas. –Live in trees –Have grasping tails

12. 6 Primate Evolution – Old world monkeys are native to Africa. – spend some time in trees, but spend much of the time foraging on the ground - They have larger brains and can grasp things better.

12. 6 Primate Evolution - Homonoids are divided into hominids, great apes, and lesser apes. – Homonids include living and extinct humans.

12. 6 Primate Evolution • Homonids walk upright, have longer lower limbs, opposable thumbs, and large brains • Include all species in the human lineage, both modern and extinct. • The skeletal changes required to walk upright can be seen in intermediate fossils between homonoids.

12. 6 Primate Evolution • Bipedal means walking on two legs. • Walking upright has important adaptive advantages. – foraging – carrying infants and food – using tools

12. 6 Primate Evolution There are many fossils of extinct hominids. • Most hominids are either the genus Australopithecus or Homo. • Australopithecines were a successful genus. • The Homo genus first evolved 2. 4 million years ago.

12. 6 Primate Evolution Modern humans arose about 100, 000 years ago. • Homo sapiens fossils date to 100, 000 years ago in Ethopia. • Human evolution is influenced by a tool-based culture. • There is a trend toward increased brain size in hominids. Australopithecus afarensis Homo habilis Homo neanderthalensis Homo sapiens