Human Evolution

By

Farshid Mokhberi

Shahid Beheshti University Of Medical Sciences and Health Service

OverviewEvolution of PrimatesEvolution of HominidsFocus on HomoHuman VariationHumans as a selective agent

Early Primates

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

First Arboreal MammalsThe first arboreal mammals probably

resembled shrews:long snouts.Good sense of smell.Probably nocturnal.Very active.CLAWS

First Arboreal Mammals

EosimiasThe First Primate?

TarsiersTarsiersLemursLemurs

LorisPottos

ProsimiansProsimians

Primate CharacteristicsWhat is the major selective

pressure associated with life in the trees?

How are primates adapted to this life?

Binocular Color Vision

Mobile LimbsMost 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 featuresUpright posture. Small litter size. Expanded forebrain, larger brain

capacity.

Two main groups of primates:

1. Prosimians – lemurs, lorises, pottos & tarsiers

2. Anthropoids – monkeys, apes and man

TarsiersTarsiersLemursLemurs

LorisPottos

ProsimiansProsimians

ANTHROPOIDS2. Anthropoids = monkeys + apes + man2. Anthropoids = monkeys + apes + man

a.a. Monkeys:Monkeys:

• Old world monkeysOld world monkeys

• New world monkeysNew world monkeys

New World Monkey:

Flat face

Wide nostrils

Prehensile tail

Old World Monkey:

Long snout

Close nostrils

Non-prehensile tail

Taxonomy Anthropoids= Hominoids +

monkeysHominoids= Asian and African

Apes + HominidsHominids= Humans

Proconsul- Ancestor to Hominoids?

A skull of Proconsul africanus from the Kenya National Museum.

Selective pressures

East Africa Rift Valley

Skull Comparisons:

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

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

““LucyLucy” ” Australopithecus afarensisAustralopithecus afarensis

An Example of Mosaic Evolution

A. afarensis

A. africanus

A. boisei

A. robustus

Australopithecus africanus

2.8 million years agoCranial capacity 460 cc

Homo habilis

Artist’s representation of a Homo habilis band as it might have existed two million years ago.

Brain~600cc

“Handy Man”

Olduwan tools

Speech?

Homo erectus“Upright Man”Larger brain than H. habilisMigratedAcheulean toolsMore advanced culture?

Homo erectus

Homo erectus

NeanderthalsNeanderthal (H. neanderthalensis) skeletons were

first discovered in Germany’s Neander Valley.Skeletons date back 200,000 years.

Neanderthal Culture

Neanderthal Man

Homo floresiensis – Nature, Oct. 28, 2004

Nature

Oct 28, 2004

Science, Nov 19, 2004

Homo sapiensArchaic – 100,000 to

35,000 years BPSometimes called Homo

sapiens and Homo sapiens neanderthalensis

Modern – 35,000 years BP to presentAnatomically modernSometimes called Homo

sapiens sapiens

Cro-MagnonsOldest 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 Cro-Magnon

humanshumans 1,600 cc cranial 1,600 cc cranial

capacitycapacity NotNot a different a different

species, just old species, just old Homo sapiensHomo sapiens from Europefrom Europe

Artist’s reconstruction of a Cro-Magnon man

Archaic H. sapiens Culture ArtArt

Female figurinesFemale figurines 27,000 to 22,000 27,000 to 22,000

years agoyears ago Called “venuses,”Called “venuses,”

Archaic H. sapiens Culture

Human VariationResponses to the environment:• Bergmann’s Rule

• Allen’s Rule

Common ancestor

Homo sapiens

Modern apes

Australopithecus afarensis

Australopithecus africanus

Homo habilis

Homo erectus

Homo neanderthalensis