Biology, 9th ed, Sylvia Mader Chapter 32 Chapter 32 Human Evolution Human Evolution

Evolution of Early Hominids Evolution of Later Hominids Outline Evolution of Primates Mobile Limbs Binocular Vision Evolution of Early Hominids Evolution of Later Hominids Evolution of Early Homo Modern Humans Human Variation

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

Primate Diversity

Mobile Limbs Hands and feet Most primates have flat nails 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

Evolution of Primate Hand

Binocular Vision Stereoscopic vision Depth perception Allows primates to make accurate judgments about distance and position of adjoining tree limbs

Binocular Vision

Primate Characteristics Opposable thumb Nails instead of claws Single births Binocular vision Expanded, complex brain Emphasis on learned behavior

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

Evolution of primates

Proconsul is believed ancestral to hominids Evolution of Hominids Proconsul is believed ancestral to hominids Phylogenetic tree indicates humans are most closely related to African apes Genetic changes used as a molecular clock to measure relatedness of different groups Last common ancestor appears to have lived about 7 mya

Monkey Skeleton Compared to Proconsul Skeleton

Skeletal differences between humans and apes largely because: Hominids Hominid fossils: Must have an anatomy suitable for standing erect and walking on two feet Bipedalism Skeletal differences between humans and apes largely because: Humans are bipedal, while Apes are quadrupedal

Adaptations for Standing

Australopithecines Australopithecines: Evolved and diversified in Africa 4 mya Possibly a direct ancestor of humans Southern Africa Australopithecus africanus Eastern Africa Australopithecus afarensis

Human Evolution

Australopithecus afarensis

Evolution of Early Homo Homo habilis Dated between 20 an 19 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

Homo erectus and similar fossils Found in Africa, Asia, and Europe Dated between 19 and 03 mya Larger brain and flatter face than Homo habilis Much taller than previous hominids Thought to have first appeared in Africa and then migrated into Asia and Europe First hominid to use fire

Homo ergaster

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

Evolution of Modern Humans

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

Neandertals

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

Cro-Magnons

Comparative study of mitochondrial DNA Human Variation 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 Comparative study of mitochondrial DNA Suggests human populations have a common ancestor no more than a million years ago

Ethnic Groups

Evolution of Early Hominids Evolution of Later Hominids Review Evolution of Primates Mobile Limbs Binocular Vision Evolution of Early Hominids Evolution of Later Hominids Evolution of Early Homo Modern Humans Human Variation

Biology, 9th ed, Sylvia Mader Chapter 32 Ending Slide Chapter 32 Human Evolution Human Evolution