Human Evolution Chapter 32-Mader

Overview Evolution of Primates Evolution of Hominids Focus on Homo Human Variation Humans as a selective agent

Early Primates Prosimians (~58mya) Monkeys (35mya) Apes (23mya) Hominids (~6mya)

First Arboreal Mammals The first arboreal mammals probably resembled shrews: long snouts. Good sense of smell. Probably nocturnal. Very active. CLAWS

First Arboreal Mammals?

Eosimias The First Primate? Comparison with tree shrew

Prosimians Lemurs Tarsiers Pottos Loris

Tarsier

Ring tailed lemur

Indri

Aye aye what do they sound like? This

Slender loris

Primate Characteristics What is the major selective pressure associated with life in the trees? How are primates adapted to this life? ?

Binocular Color Vision

Primate Hands

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.

Other important features Upright posture. Small litter size. Expanded forebrain, larger brain capacity. Advantages?

separated.

Two main groups of primates: 1. Prosimians – lemurs, lorises, pottos & tarsiers 2. Anthropoids – monkeys, apes and man

Prosimians Lemurs Tarsiers Pottos Loris

2. Anthropoids = monkeys + apes + man Old world monkeys New world monkeys Old World Monkey: Long snout Close nostrils Non-prehensile tail New World Monkey: Flat face Wide nostrils Prehensile tail

Taxonomy Anthropoids= Hominoids + monkeys Hominoids= Asian and African Apes + Hominids Hominids= Humans

Proconsul- Ancestor to Hominoids?

Proconsul A skull of Proconsul africanus from the Kenya National Museum.

Selective pressures East Africa Rift Valley

Skull Comparisons:

Sahelanthropus tchadensis 6 to 7 million years ago Flat face like Homo Cranial capacity about the same as a chimp Walked upright

Hominids Bipedal primates.

To be Human standard primate characteristics upright, bipedal posture much expanded brain well defined sexual dimorphism hidden estrus altered female sexual response extended childhood language society culture

Homo erectus, Australopithecus,& Human

Map of Australopithecine Finds Map of Australopithecus sites in Africa, with a focus on the East African rift valley and limestone caves of South Africa.

“Lucy” Australopithecus afarensis An Example of Mosaic Evolution

A. boisei A. afarensis A. africanus A. robustus

Human Ancestors

Human Evolution

Australopithecus africanus 2.8 million years ago Cranial capacity 460 cc

Genus Homo

Homo habilis Brain~600cc “Handy Man” Olduwan tools Speech? Artist’s representation of a Homo habilis band as it might have existed two million years ago.

Oldowan Tools

Homo erectus “Upright Man” Larger brain than H. habilis Migrated Acheulean tools More advanced culture?

Homo erectus

Homo erectus

Trends in Skull Development

Neanderthals Neanderthal (H. neanderthalensis) skeletons were first discovered in Germany’s Neander Valley. Skeletons date back 200,000 years.

Neanderthal Culture

What happened to Neandertals? Coexisted w/H. sapiens for up to 60,000 years. Interbred? Killed off? Outcompeted?

Neanderthal Man

Homo floresiensis – Nature, Oct. 28, 2004

Nature Oct 28, 2004

Science, Nov 19, 2004

Homo sapiens Archaic – 100,000 to 35,000 years BP Sometimes called Homo sapiens and Homo sapiens neanderthalensis Modern – 35,000 years BP to present Anatomically modern Sometimes called Homo sapiens sapiens

Cro-Magnons Oldest fossils to be designated H. sapiens. Modern humans who entered Asia and Europe from Africa 100,000 years ago. Aurignacian tools. Accomplished hunters. Language.

Cro-Magnon Man Cro-Magnon humans 1,600 cc cranial capacity Not a different species, just old Homo sapiens from Europe Artist’s reconstruction of a Cro-Magnon man

Archaic H. sapiens Culture Art Female figurines 27,000 to 22,000 years ago Called “venuses,”

Archaic H. sapiens Culture

Human Variation Responses to the environment: Bergmann’s Rule Allen’s Rule

New World Humans

Sequence of Human Evolution One of several possibilities Homo neanderthalensis Australopithecus afarensis Australopithecus africanus Homo erectus Common ancestor Homo habilis Homo sapiens Modern apes