Evolution of Early Hominids Evolution of Later Hominids CH 32 - 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

Prosimians Primate Diversity 4 Prosimians are a type of primate that include lemurs, lorises, bushbabies, and tarsiers, but not monkeys, apes, or humans (simians). They are considered to have characteristics that are more "primitive" than those of monkeys and apes. Prosimians are the only primates native to Madagascar, and are also found in Africa and Asia. Primate Diversity 4

New World Monkeys New World monkeys differ slightly from Old World monkeys in several aspects. The most distinction is the nose, which is the feature used most commonly to distinguish between the two groups. The scientific name for the New World monkeys, Platyrrhini, means "flat nosed". New World monkeys are the only monkeys with prehensile tails—in comparison with the shorter, non-grasping tails of the anthropoids of the Old World.

Old World Monkeys Old world monkeys are more closely related to apes than new world monkeys

Old World Monkeys The Old World monkeys are native to Africa and Asia today, inhabiting a range of environments from tropical rain forest to savanna, shrubland and mountainous terrain, and are also known from Europe in the fossil record. Old World monkeys are medium to large in size, and range from arboreal forms, such as the colobus monkeys, to fully terrestrial forms, such as the baboons.

Apes: African, Asia, and Human?

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

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 1. Location of spine in skull 2 Adaptations for Standing 1. Location of spine in skull 2. Human spine is S-shaped; ape spine is curved. 3. Human pelvis is bowl shaped; ape pelvis is long and more narrow. 4. Humans femur angle in towards the knees; ape femurs angle out. 5. Human knees can support more weight than ape knees. 6. Human foot has an arch; ape foot has no arch.

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 The specimen was discovered in 1974 at Hadar in the Awash Valley of Ethiopia’s Afar Depression by Donald Johansson of the Cleveland Museum of Natural History Lucy is estimated to have lived 3.2 million years ago.[ The discovery of this hominid was significant as the skeleton shows evidence of small skull capacity akin to that of apes and of bipedal upright walk akin to that of humans Providing further evidence supporting the view that bipedalism preceded increase in brain size in human evolution

Australopithecus afarensis Named “Lucy” after the Beatles song “Lucy in the Sky with Diamonds” Several hundred pieces of bone representing about 40% of the skeleton

Evolution of Early Homo Homo habilis Dated between 2.3 and 1.4 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 1.9 and 0.3 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 Which of these makes more sense and why?

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