Human Evolution Chapter 32 Mader: Biology 8th Ed.

Outline Evolution of Primates Mobile Limbs Binocular Vision Evolution of Hominids Early Homo Modern Humans Human Variation Mader: Biology 8th Ed.

Evolution of Primates The evolution of primates is characterized by trends towards mobile limbs, grasping hands, a flattened face, binocular vision, a large, complex brain, and a reduced reproductive rate. Mader: Biology 8th Ed.

Many also have both an opposable big toe and thumb. Mobile Limbs Most primates have flat nails as well as sensitive pads on the undersides of fingers and toes. Many also have both an opposable big toe and thumb. Mobile limbs and clawless opposable digits allow primates to freely grasp and release tree limbs. Mader: Biology 8th Ed.

Primate Hands Mader: Biology 8th Ed.

Binocular Vision Stereoscopic vision and resultant depth perception allows primates to make accurate judgments about distance and position of adjoining tree limbs. Mader: Biology 8th Ed.

Primate Characteristics Opposable thumb Nails instead of claws. Single births Binocular vision Expanded, complex brain. Emphasis on learned behavior. Mader: Biology 8th Ed.

Surviving anthropoids are classified into three superfamilies. Evolution of Primates Prosimians were the first type of primate to diverge from the human line. Surviving anthropoids are classified into three superfamilies. New World monkeys Old World monkeys Hominoids Mader: Biology 8th Ed.

Proconsul is believed ancestral to hominids. Hominoid Evolution Proconsul is believed ancestral to hominids. Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Last common ancestor appears to have lived about 7 mya. Evolution of Hominids Phylogenetic tree indicates humans are most closely related to African apes. Last common ancestor appears to have lived about 7 mya. Genetic changes used as a molecular clock to measure relatedness of different groups. Mader: Biology 8th Ed.

Hominids To be a hominid, a fossil must have an anatomy suitable for standing erect and walking on two feet. Bipedalism Human anatomy differs from that of an ape largely because humans are bipedal while apes are quadrupedal. Mader: Biology 8th Ed.

Australopithecus africanus Eastern Africa Australopithecus afarensis Australopithecines It is possible that one of the australopithecines that evolved and diversified in Africa 4 mya is a direct ancestor of humans. Southern Africa Australopithecus africanus Eastern Africa Australopithecus afarensis Mader: Biology 8th Ed.

Evolution of Early Homo Homo habilis, dated between 2.0 an 1.9 mya, may be ancestral to modern humans. Skulls suggest portions of the brain associated with speech were enlarged. Ability to speak may have led to hunting cooperatively and the advent of culture. Mader: Biology 8th Ed.

Human Evolution Mader: Biology 8th Ed.

Larger brain and flatter face than Homo habilis. Homo erectus Homo erectus and like fossils are found in Africa, Asia, and Europe and are dated between 1.9 and 0.3 mya. Larger brain and flatter face than Homo habilis. Much taller than previous hominids. Believed to have first appeared in Africa and then migrated into Asia and Europe. First hominid to use fire. Mader: Biology 8th Ed.

Evolution of Modern Humans Most researchers believe Homo sapiens evolved from Homo erectus. Multiregional Continuity Hypothesis Similar evolution occurred in many different places. Out-of-Africa Hypothesis H. sapiens evolved from H. erectus only in Africa, and thereafter migrated to Europe. Mader: Biology 8th Ed.

Evolution of Modern Humans Mader: Biology 8th Ed.

Skeletons date back 200,000 years. Neanderthals Neanderthal (H. neanderthalensis) skeletons were first discovered in Germany’s Neander Valley. Skeletons date back 200,000 years. Massive brow ridges with protruding nose, jaws, and teeth. Heavily muscled. Culturally advanced. Manufactured variety of tools. Mader: Biology 8th Ed.

Oldest fossils to be designated H. sapiens. Cro-Magnons Oldest fossils to be designated H. sapiens. Modern humans who entered Asia and Europe from Africa 100,000 years ago. Made advanced stone tools. Accomplished hunters. Hunted cooperatively. First to have language. Mader: Biology 8th Ed.

Human Variation It has been hypothesized that human variations evolved as adaptations to local environmental conditions. Bergmann’s Rule - Animals in colder regions of their range have a bulkier body build. Allen’s Rule - Animals in colder regions of their range have shorter limbs, digits, and ears. Mader: Biology 8th Ed.

Human Variation Comparative study of mitochondrial DNA shows differences among human populations are consistent with their having a common ancestor no more than a million years ago. Mader: Biology 8th Ed.

Review Evolution of Primates Mobile Limbs Binocular Vision Evolution of Hominids Early Homo Modern Humans Human Variation Mader: Biology 8th Ed.

Mader: Biology 8th Ed.