Chapter 17
Early Conditions on Earth
Primordial Soup
 Atmosphere of carbon dioxide,
methane, hydrogen sulfide, ammonia &
other toxic gases
 Very little free oxygen
 Very high temperatures
 Lots of raw energy; much upheaval
(earthquakes, volcanoes, lightning, etc.)
Raw materials necessary for the basic biological
macromolecules were present in the oxygenfree atmosphere
 The abundance of intense energy (electrical,
heat, & radiation) may have caused chemical
reactions that formed simple organic molecules
 Free oxygen in the atmosphere would have
prevented these molecules from forming

o 4.5 BYA – formation of the Earth
o 4.5 BYA – formation of the Earth
o 4.0 BYA – first life on earth (prokaryotic)
o 4.5 BYA – formation of the Earth
o 4.0 BYA – first life on earth (prokaryotic)
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o 4.5 BYA – formation of the Earth
o 4.0 BYA – first life on earth (prokaryotic)
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 4.5 BYA – formation of the Earth
o 4.0 BYA – first life on earth (prokaryotic)
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o 4.5 BYA – formation of the Earth
o 4.0 BYA – first life on earth (prokaryotic)
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o 540 MYA – “Cambrian explosion”
o 4.5 BYA – formation of the Earth
o 4.0 BYA – first life on earth (prokaryotic)
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o 540 MYA – “Cambrian explosion”
o 500 MYA – plants, fungi, & animals colonize
land
o 4.5 BYA – formation of the Earth
o 4.0 BYA – first life on earth (prokaryotic)
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o 540 MYA – “Cambrian explosion”
o 500 MYA – plants, fungi, & animals colonize
land
o 440 MYA – “Ordovician-Silurian extinction” –
most marine species died out
o 395 MYA – first insects on land
o 4.5 BYA – formation of the Earth
o 4.0 BYA – first life on earth (prokaryotic)
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o 540 MYA – “Cambrian explosion”
o 500 MYA – plants, fungi, & animals colonize
land
o 440 MYA – “Ordovician-Silurian extinction” –
most marine species died out
o 395 MYA – first insects on land
o 365 MYA – “Late Devonian extinction” – 70%
of marine species died out; first amphibians
& trees
o 313 MYA – first reptiles
o 4.5 BYA – formation of the Earth
o 4.0 BYA – first life on earth (prokaryotic)
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o 540 MYA – “Cambrian explosion”
o 500 MYA – plants, fungi, & animals colonize
land
o 440 MYA – “Ordovician-Silurian extinction” –
most marine species died out
o 395 MYA – first insects on land
o 365 MYA – “Late Devonian extinction” – 70%
of marine species died out; first amphibians
& trees
o 313 MYA – first reptiles
o 250 MYA – “Permian-Triassic extinction” –
90% of all species on Earth died out!
Formation of supercontinent Pangaea
PERMIAN
225 MYO
o 4.5 BYA – formation of the Earth
o 4.0 BYA – first life on earth (prokaryotic)
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o 540 MYA – “Cambrian explosion”
o 500 MYA – plants, fungi, & animals colonize
land
o 440 MYA – “Ordovician-Silurian extinction” –
most marine species died out
o 395 MYA – first insects on land
o 365 MYA – “Late Devonian extinction” – 70%
of marine species died out; first amphibians
& trees
o 313 MYA – first reptiles
o 250 MYA – “Permian-Triassic extinction” –
90% of all species on Earth died out!
Formation of supercontinent Pangaea
o 235 MYA – first dinosaurs & flowers
o 4.5 BYA – formation of the Earth
o 4.0 BYA – first life on earth (prokaryotic)
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o 540 MYA – “Cambrian explosion”
o 500 MYA – plants, fungi, & animals colonize
land
o 440 MYA – “Ordovician-Silurian extinction” –
most marine species died out
o 395 MYA – first insects on land
o 365 MYA – “Late Devonian extinction” – 70%
of marine species died out; first amphibians
& trees
o 313 MYA – first reptiles
o 250 MYA – “Permian-Triassic extinction” –
90% of all species on Earth died out!
Formation of supercontinent Pangaea
o 235 MYA – first dinosaurs & flowers
o 205 MYA – “Triassic-Jurassic extinction” –
end of large amphibians and many reptiles
o 200 MYA – Pangaea began to split into
separate continents
PERMIAN
225 MYO
TRIASSIC
200 MYO
JURASSIC
135 MYO
CRETACEOUS
65 MYO
PRESENT DAY
TRIASSIC
200 MYO
JURASSIC
135 MYO
PERMIAN
225 MYO
PRESENT DAY
CRETACEOUS
65 MYO
o 4.5 BYA – formation of the Earth
o 150 MYA – first birds
o 4.0 BYA – first life on earth (prokaryotic)
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o 540 MYA – “Cambrian explosion”
o 500 MYA – plants, fungi, & animals colonize
land
o 440 MYA – “Ordovician-Silurian extinction” –
most marine species died out
o 395 MYA – first insects on land
o 365 MYA – “Late Devonian extinction” – 70%
of marine species died out; first amphibians
& trees
o 313 MYA – first reptiles
o 250 MYA – “Permian-Triassic extinction” –
90% of all species on Earth died out!
Formation of supercontinent Pangaea
o 235 MYA – first dinosaurs & flowers
o 205 MYA – “Triassic-Jurassic extinction” –
end of large amphibians and many reptiles
o 200 MYA – Pangaea began to split into
separate continents
o 4.5 BYA – formation of the Earth
o 150 MYA – first birds
o 4.0 BYA – first life on earth (prokaryotic)
o 114 MYA – first modern mammals; world
begins to cool
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o 540 MYA – “Cambrian explosion”
o 500 MYA – plants, fungi, & animals colonize
land
o 440 MYA – “Ordovician-Silurian extinction” –
most marine species died out
o 395 MYA – first insects on land
o 365 MYA – “Late Devonian extinction” – 70%
of marine species died out; first amphibians
& trees
o 313 MYA – first reptiles
o 250 MYA – “Permian-Triassic extinction” –
90% of all species on Earth died out!
Formation of supercontinent Pangaea
o 235 MYA – first dinosaurs & flowers
o 205 MYA – “Triassic-Jurassic extinction” –
end of large amphibians and many reptiles
o 200 MYA – Pangaea began to split into
separate continents
o 4.5 BYA – formation of the Earth
o
o 4.0 BYA – first life on earth (prokaryotic)
o
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o 540 MYA – “Cambrian explosion”
o 500 MYA – plants, fungi, & animals colonize
land
o 440 MYA – “Ordovician-Silurian extinction” –
most marine species died out
o 395 MYA – first insects on land
o 365 MYA – “Late Devonian extinction” – 70%
of marine species died out; first amphibians
& trees
o 313 MYA – first reptiles
o 250 MYA – “Permian-Triassic extinction” –
90% of all species on Earth died out!
Formation of supercontinent Pangaea
o 235 MYA – first dinosaurs & flowers
o 205 MYA – “Triassic-Jurassic extinction” –
end of large amphibians and many reptiles
o 200 MYA – Pangaea began to split into
separate continents
150 MYA – first birds
114 MYA – first modern mammals; world
begins to cool
67 MYA – asteroid hit Mexico, causing the
“Cretaceous-Tertiary extinction;” end of
dinosaurs; 50% of all species died out;
intensified global cooling
o 4.5 BYA – formation of the Earth
o
o 4.0 BYA – first life on earth (prokaryotic)
o
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o
o 540 MYA – “Cambrian explosion”
o 500 MYA – plants, fungi, & animals colonize
land
o 440 MYA – “Ordovician-Silurian extinction” –
most marine species died out
o 395 MYA – first insects on land
o 365 MYA – “Late Devonian extinction” – 70%
of marine species died out; first amphibians
& trees
o 313 MYA – first reptiles
o 250 MYA – “Permian-Triassic extinction” –
90% of all species on Earth died out!
Formation of supercontinent Pangaea
o 235 MYA – first dinosaurs & flowers
o 205 MYA – “Triassic-Jurassic extinction” –
end of large amphibians and many reptiles
o 200 MYA – Pangaea began to split into
separate continents
150 MYA – first birds
114 MYA – first modern mammals; world
begins to cool
67 MYA – asteroid hit Mexico, causing the
“Cretaceous-Tertiary extinction;” end of
dinosaurs; 50% of all species died out;
intensified global cooling
21 MYA – apes split off from other monkeys
o 4.5 BYA – formation of the Earth
o
o 4.0 BYA – first life on earth (prokaryotic)
o
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o
o 540 MYA – “Cambrian explosion”
o 500 MYA – plants, fungi, & animals colonize o
o
land
o 440 MYA – “Ordovician-Silurian extinction” –
o
most marine species died out
o 395 MYA – first insects on land
o 365 MYA – “Late Devonian extinction” – 70% o
of marine species died out; first amphibians
o
& trees
o
o 313 MYA – first reptiles
o 250 MYA – “Permian-Triassic extinction” – o
o
90% of all species on Earth died out!
Formation of supercontinent Pangaea
o 235 MYA – first dinosaurs & flowers
o 205 MYA – “Triassic-Jurassic extinction” –
end of large amphibians and many reptiles
o 200 MYA – Pangaea began to split into
separate continents
150 MYA – first birds
114 MYA – first modern mammals; world
begins to cool
67 MYA – asteroid hit Mexico, causing the
“Cretaceous-Tertiary extinction;” end of
dinosaurs; 50% of all species died out;
intensified global cooling
21 MYA – apes split off from other monkeys
5 MYA – humans split off from other apes
3.9 MYA – first known Australopithecus
afarensis (Lucy)
3 MYA – Cooling trend causes year-round ice
at the North Pole
2.5 MYA – first Homo habilis; beginning of
period of repeated glaciation
1.9 MYA – first Homo erectus
1.4 MYA – first fire-making by hominids
350,000 YA – first Homo neanderthalensis
250,000 YA – first Homo sapiens
Homo sapiens
Homo erectus
Neanderthals
Homo habilis
Australopithecus
o 4.5 BYA – formation of the Earth
o
o 4.0 BYA – first life on earth (prokaryotic)
o
o 3.4 BYA – first cyanobacteria
(photosynthetic)
o
o 2.4 BYA – O2 accumulates in atmosphere
o 2.1 BYA – first eukaryotic life
o 1.3 BYA – first multicellular life
o
o 540 MYA – “Cambrian explosion”
o 500 MYA – plants, fungi, & animals colonize o
o
land
o 440 MYA – “Ordovician-Silurian extinction” –
o
most marine species died out
o 395 MYA – first insects on land
o 365 MYA – “Late Devonian extinction” – 70% o
of marine species died out; first amphibians
o
& trees
o
o 313 MYA – first reptiles
o 250 MYA – “Permian-Triassic extinction” – o
o
90% of all species on Earth died out!
Formation of supercontinent Pangaea
o
o 235 MYA – first dinosaurs & flowers
o 205 MYA – “Triassic-Jurassic extinction” – o
end of large amphibians and many reptiles o
o 200 MYA – Pangaea began to split into
separate continents
150 MYA – first birds
114 MYA – first modern mammals; world
begins to cool
67 MYA – asteroid hit Mexico, causing the
“Cretaceous-Tertiary extinction;” end of
dinosaurs; 50% of all species died out;
intensified global cooling
21 MYA – apes split off from other monkeys
5 MYA – humans split off from other apes
3.9 MYA – first known Australopithecus
afarensis (Lucy)
3 MYA – Cooling trend causes year-round ice
at the North Pole
2.5 MYA – first Homo habilis; beginning of
period of repeated glaciation
1.9 MYA – first Homo erectus
1.4 MYA – first fire-making by humans
350,000 YA – first Homo neanderthalensis
250,000 YA – first Homo sapiens
35,000 YA – extinction of Homo
neanderthalensis
32,000 YA – oldest known cave paintings
10,300 YA – end of most recent glacial
period (ice age)
0
era
1.8
Cenozoic
Geologic time scale, 650 million years ago to the present
50
period
Quaternary
Tertiary
100
Mammals diversify
Extinction of dinosaurs
First primates
First flowering plants
Mesozoic
150
Cretaceous
events
Evolution of humans
Jurassic
First birds
Dinosaurs diversify
Triassic
First mammals
First dinosaurs
Permian
Major extinctions
Reptiles diversify
200
Carboniferous
300
400
Paleozoic
350
Pennsylvanian
Mississippian
Devonian
First vascular land plants
Ordovician
Sudden diversification of
metazoan families
Cambrian
First fishes
First chordates
500
550
600
650
First reptiles
Scale trees
Seed ferns
First amphibians
Jawed fishes diversify
Silurian
450
Late Proterozoic
Millions of years ago
250
Precambrian (90%
of Earth’s history)
First skeletal elements
First soft-bodied metazoans
First animal traces
Divergent Evolution
 Accumulation of differences in allele frequencies between reproductively
isolated populations of a species
 Accumulation of differences between organisms with a recent common
ancestor
 One species evolves into several different forms
Divergent Evolution
 Accumulation of differences in allele frequencies between reproductively
isolated populations of a species
 Accumulation of differences between organisms with a recent common
ancestor
 One species evolves into several different forms
 Adaptive radiation (i.e. Darwin’s finches)
Warbler finch
Cactus finch
Woodpecker finch
Sharp-beaked finch
Small insectivorous
tree finch
Large
insectivorous
tree finch
Small ground
finch
Cactus
eater
Insect eaters
Medium
ground finch
Seed eaters
Vegetarian
tree finch
Bud eater
Large
ground finch
Convergent Evolution
 Process by which unrelated organisms independently evolve similarities when
adapting to similar environments
 Results in increased resemblance between unrelated species
 Examples:
 Birds & bats
 Dolphins & sharks
Bat
Mouse
Bird
Forelimbs evolved
into wings
Four limbs
evolved
Crocodile
Coevolution
 Simultaneous evolution of adaptations in two or more populations that
interact so closely that each is a strong selective force on the other
 Joint evolution of two or more closely interacting species; when one species
evolves, the change affects selection pressures operating between the two
species and so the other also evolves
 Process by which two species evolve in response to changes in each other
 Examples:
 May result in symbiotic relationships
 Central American bullhorn acacia tree & acacia ants
 Tree provides ants with food and shelter
 Ants protect tree from leaf-eating animals
Food & shelter
Defense system
Coevolution
 Simultaneous evolution of adaptations in two or more populations that
interact so closely that each is a strong selective force on the other
 Joint evolution of two or more closely interacting species; when one species
evolves, the change affects selection pressures operating between the two
species and so the other also evolves
 Process by which two species evolve in response to changes in each other
 Examples:
 May result in symbiotic relationships
 Central American bullhorn acacia tree & acacia ants
 Tree provides ants with food and shelter
 Ants protect tree from leaf-eating animals
 Angraecoid orchids and african moths:
 Moths depend on the flowers for nectar
 Flowers are dependent on the moths
to spread pollen for reproduction
 Coevolution has lead to deep flowers
and moths with long mouthparts.
Coevolution
 Simultaneous evolution of adaptations in two or more populations that
interact so closely that each is a strong selective force on the other
 Joint evolution of two or more closely interacting species; when one species
evolves, the change affects selection pressures operating between the two
species and so the other also evolves
 Process by which two species evolve in response to changes in each other
 Examples:
 May result in symbiotic relationships
 Central American bullhorn acacia tree & acacia ants
 Tree provides ants with food and shelter
 Ants protect tree from leaf-eating animals
 Angraecoid orchids and african moths:
 Moths depend on the flowers for nectar
 Flowers are dependent on the moths
to spread pollen for reproduction
 Coevolution has lead to deep flowers
and moths with long mouthparts.
 “Arms race” between predator and prey
 Predators become faster and stealthier
 Prey evolves camouflage or speed