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EVOLUTION
Ch. 23
Evolution
Evolution Outline
• Formation of the earth & chemical evolution
• Early beginnings of cells
• Critical events leading to evolution Evidence
• Evidence supporting evolution
• Early Primate evolution
• Evolution of the Genus Australopithecines
• Evolution of the Genus Homo & modern humans
4.5 billion years ago the earth formed
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•Dr. Stanley Miller (1930-2007)
Miller’s Experiment showed:
• Organic molecules can be formed from
components of Earth’s early atmosphere.
heterotrophs
autotrophs
Collections of polymers.
SUMMARY
Earth formed
Chemical Evolution began
4.5 billion years ago
4 billion years ago
First Prokaryotes emerged
3.5 billion years ago
First Eukaryotes emerged
1.2 billion years ago
Insects 40 million
years ago trapped in
amber
Ocean
First species to invade the land came from the oceans were likely plants.
Soon after the plants invaded, animals came ashore.
First animals were probably scropion-like.
Evolutionary changes
• Anatomical
• Functional
• Behavioral
How do these changes occur?
Charles Darwin: 1809-1882
1831-1836
1859
DARWIN’s TRAVELS
2 conflicting theories
Key components of evolutionary
process
• Genetic variation
• Natural selection
• Survival of the Fittest
Evidence supporting natural
selection
1. Fossil records
2. Homologous structures
3. Biochemical similarities
(DNA of fossils is also being studied)
– DNA
– Amino acids
Humans
98% similar
Chimpanzees
4. Embryologic development
Mouse
Human
Cockatiel
Sea urchin
• 5. Biogeography
Super continent 240 million years ago
• 6. Experimental Evidence
Primate Evolution
Earliest primates included the
Tarsiers
Ruff
lemur
tarsier
Consist of
Prosimians
Old world monkeys
Primates (order)
Anthropoids
New world monkeys
hominoids
Consist of:
Great Apes
Lesser Apes
Hominids
Genus:Australopithecus
Mandrill
Spider Monkey
Genus: Homo
Australopithecus afarensis
“Lucy”
Approx. 25-30 years old
Approx. 60 pounds
Approx. 3 ft tall
Discovered by
Dr. Donald Johanson mid 70’s
Approx. 3.2 mya
Australopithecus afarensis
• Bipedal
• Approximately 3 to 5.6 ft in height
• Over 1 million years ago
Australopithecus disappeared.
Homo habilis
“skillful man”
• Lived 1.8 million years ago
• Discovered 1960 in Tanzania
by Dr. Mary Leakey
Brain is 50% larger than Australopithecus
Homo erectus
“upright man”
• Lived 1.6 million years ago
• H. erectus moved from Africa to
Europe and Asia
Used fire
Homo erectus
(stood approximately 5 ft tall)
Turkana Boy
Found in 1984 in Kenya
male
Approximately 12 years old
Lived approximately 1.6 million years ago
Homo sapien
“thinking man”
• Emerged approx. 300,000 years ago
• 2 subspecies
– neaderthalensis
– sapien
Skull of Homo sapien neanderthalensis
Lived in small clans and had elaborate burial rituals.
Homo sapien sapien
• Neaderthanls disappeared
about 40,000 years ago
• About 300,000 years ago
enter Homo sapien sapien
Skull of early Homo sapien sapien
Cro-Magnon Man
Homo sapien sapien
Cro-Magnon Man
Artistic with perhaps a well developed language
Excellent hunters
Lived in communities
Homo sapien sapien
“modern man”
• Appeared approximately 10,000 years ago
• Very little change over the past 40,000 years
The End
(or beginning !)
An artist’s interpretation of how “Lucy” may have looked.