Month Day
Lecture
Oct
Fungi
The coral reef
Animals—worms
Animals—vertebrates
Mammals
Primates to humans
Exam review
Exam
13
16
18
20
23
25
27
30
Chordates
Echinoderms
Arthropods
Annelids
Coelomate
Ancestry
Mollusks
Rotifers
Roundworms
Bilateral
Ancestry
Radial
Ancestry
Multicelled
Ancestry
Flatworms
Cnidarians
Sponges
Single-celled, protistanlike ancestors
Mammals
Figure 26.2
Page 445
Birds
“Reptiles”
Amniotes
Amphibians
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
Warm, wet
After Isthmus of Panama formed
23-5 mya—the Miocene
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
precision grip
power 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
H. neanderthalensis
A. garhi
H. erectus
H. habilis
Ardipithecus ramidus
Australopithecus
Between 10 and 5 mya,
divergences leading to
gorillas, chimpanzees,
HOMINIDS
and hominids
Homo rudolfensis
A. africanus
A. robustus
A. afarensis
A. boisei
CHIMPANZEE
Between 10 and 5 mya, the
adaptive radiation of first
hominiods (apelike forms)
ANCESTRAL PRIMATES
60-40 mya
H. sapiens
GORILLA
ORANGUTAN
GIBBON
OLD WORLD MONKEYS
EARLY HOMINOIDS
NEW WORLD MONKEYS
EARLY ANTHROPOIDS
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
Tools made by australopiths and/or H. habilis
Fig. 26-37a, p.457
Reconstruction of Homo habilis in an East African woodland
Homo erectus
2 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
One family tree proposed for H. sapiens
NEW GUINEA, AUSTRALIA
PACIFIC ISLANDS
SOUTHEAST ASIA
ARCTIC, NORTHEAST ASIA
NORTH, SOUTH AMERICA
NORTHEAST ASIA
EUROPE, MIDDLE EAST
AFRICA
0.2
0.1
Genetic distance (percent)
0
40,000 years ago
Estimated times when populations of early H. sapiens were
colonizing different regions of the world