Month

Day Lecture

Oct 13 Fungi16 The coral reef18 Animals—worms20 Animals—vertebrates23 Mammals25 Primates to humans27 Exam review30 Exam

Chordates

Echinoderms

Arthropods

Annelids

Mollusks

Rotifers

Roundworms

Flatworms

Cnidarians

SpongesMulticelled Ancestry

Radial Ancestry

Bilateral Ancestry

Coelomate Ancestry

Single-celled, protistanlike ancestors

Figure 26.2Page 445

Mammals

Birds

“Reptiles”

Amphibians

Amniotes

Tetrapods

Lungfishes

Lobe-finned Fishes

Ray-finned Fishes

Cartilaginous Fishes

Jawed Vertebrates

Lampreys

Vertebrates

Craniates Hagfishes

Cephalochordates

Urochordates

Chordates

Unique characteristics of mammals:

• Mammary glands • Sweat glands• Hair• Four-chambered heart

• Other notable characteristics:– Internal fertilization of eggs– Warm-blooded

Primates evolved from an ancestral arboreal insectivore

about 60 mya

Early primates:

• Dexterous hands with opposable thumbs

• Nails instead of claws• Eyes in front-good depth

perception• Daytime vision (less reliance on

smell)

Great Apes--hominoids

• Gorillas• Orangutans• Gibbons• Humans

Our closest living relative: the chimpanzee

The ladder...

From Primates to Humans

“Uniquely” human traits

evolved through

modification of traits that

evolved earlier

in ancestral forms

Falling out of the tree

Before Isthmus of Panama formed After Isthmus of Panama formed

23-5 mya—the MioceneWarm, wet Cool, dry

Trends in Lineage Leading to Humans

• Less reliance on smell, more on vision

Trends in Lineage Leading to Humans

• Less reliance on smell, more on vision

• Modifications of hand allow fine

movements

power gripprecision grip

Trends in Lineage Leading to Humans

• Less reliance on smell, more on vision

• Modifications of hand allow fine

movements

• Bow-shaped jaw and smaller teeth

Trends in Lineage Leading to Humans

• Less reliance on smell, more on vision

• Modifications of hand allow fine

movements

• Bow-shaped jaw and smaller teeth

• Longer lifespan and period of dependency

Trends in Lineage Leading to Humans

• Less reliance on smell, more on vision

• Modifications of hand allow fine movements

• Bow-shaped jaw and smaller teeth

• Longer lifespan and period of dependency

• Skeletal changes to allow bipedalism

– Not as efficient as quadrupedal movement, but keeps eyes

up and forward, keeps hands free

ANCESTRAL PRIMATES 60-40 mya

Between 10 and 5 mya, the adaptive radiation of first hominiods (apelike forms)

Between 10 and 5 mya, divergences leading to gorillas, chimpanzees, and hominids

EARLY HOMINOIDS

EARLY ANTHROPOIDS

HOMINIDS A. afarensis A. boisei

A. robustusA. africanus

Homo rudolfensis

Australopithecus

Ardipithecus ramidus

A. garhi H. erectus

H. neanderthalensis

H. sapiensH. habilis

CHIMPANZEE

GORILLA

ORANGUTAN

GIBBON

OLD WORLD MONKEYS

NEW WORLD MONKEYS

PROSIMIANS

4 mya 3 mya 2 mya 1 mya present

Fig. 26-38, p.457

Earliest Fossils Are African

• Sub-saharan Africa appears to be

the cradle of human evolution

• No human fossils older than 2

million years exist anywhere but

Africa

Fig. 26-37a, p.457Tools made by australopiths and/or H. habilis

Reconstruction of Homo habilis in an East African woodland

Homo erectus2 million-53,000? years

ago• Evolved in Africa

• Migrated into Europe and Asia from

2 million to 500,000 years ago

• Larger brain than H. habilis

• Creative toolmaker

• Built fires and used furs for clothing

Homo sapiens

• Modern man evolved by 100,000 years ago

• Compared to Homo erectus:– Smaller teeth and jaws– Chin– Smaller facial bones– Larger-volume brain case

Neanderthals

• Early humans that lived in Europe and Near East

• Massively built, with large brains

• Disappeared when H. sapiens appeared

• DNA evidence suggests that they did not contribute to modern European populations

40,000 years ago

Estimated times when populations of early H. sapiens were colonizing different regions of the world

Where Did H. sapiens Arise?

• Two hypotheses:

– Multiregional model

– African emergence model

• Both attempt to address biochemical and fossil evidence

Multiregional Model

• Argues that H. erectus migrated to many locations by about 1 million years ago

• Geographically separated populations gave rise to phenotypically different races of H. sapiens in different locations (parallel evolution)

• Gene flow prevented races from becoming species

African Emergence Model

• Argues that H. sapiens arose in sub-Saharan Africa

• H. sapiens migrated out of Africa and into regions where H. erectus had preceded them (and likely outcompeted them)

• Only after leaving Africa did phenotypic differences arise

NEW GUINEA, AUSTRALIA

PACIFIC ISLANDS

SOUTHEAST ASIA

ARCTIC, NORTHEAST ASIA

NORTH, SOUTH AMERICA

NORTHEAST ASIA

EUROPE, MIDDLE EAST

AFRICA0.2

0.1 0

Genetic distance (percent)

One family tree proposed for H. sapiens

40,000 years ago

Estimated times when populations of early H. sapiens were colonizing different regions of the world