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The Origin and Evolution
of Life
The History of Life on
Earth
Chapters 21& 22
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Evolutionary Thought
• What is evolution?
– Evolution simply mean “change”
• The problem comes when trying to determine
how life began
• Through the years, many people have tried to
understand and explain how life could have
come about (Aristotle)
• Why try to explain?
Theory of Evolution
• Enter Charles Darwin
• Charles Darwin was 23 years old when he
was convinced to take the place of the
naturalist on the H.M.S. Beagle.
• The ship sailed for 5 years (1831-36)
circling the globe discovering new
species of plants and animals.
• Darwin was the person who drew all the
illustrations of animals and plants
discovered on the voyage.
Voyage of the HMS Beagle
On the Origin of Species by Means of Natural Selection
by Charles Darwin
• In 1838, Darwin read Malthus:
“populations… tend to increase beyond
capacity of their environment to
support them”
• Studied, experimented, pondered and
wrote for 20 years
• 1858 Darwin read Wallace’s essay on
Natural Selection—pushed Darwin to
finish book
• Published in 1859
• Huge hit
Darwin’s Theories
• Darwin eventually came up with five
theories:
• 1. Perpetual change—basic theory or
foundation-- now considered a
scientific fact, species change.
• 2. Multiplication of species—new
species formed by splitting and
transforming of older ones. Species
will increase through time, although
most will become extinct.
•
• 3. Gradualism—gradual minute
changes over a long period of time.
• 4. Common descent—phylogeny:
everything came from one common
ancestor “into which life was first
breathed.”
• 5. Natural Selection—Variation among
organisms
Darwin’s “Finches”
Early Tree of
Life
(1874)
Ernst Haeckel
showing
“common
descent”
Modern Darwinism
• Neo-Dawinism: With the advent of genetics,
came population genetics
• out of that came two fields of study:
– 1. Microevolution: evolutionary changes
in frequencies of variant forms of genes
(alleles) within populations
• Peppered moths of England
Peppered Moths
Modern Darwinism
– 2. Macroevolution: evolution on a grand scale
– Speciation: new species formed
• What determines a Species?
• HOW?
• Gradual divergence? –proceeds over
time more or less steadily
• Punctuated equilibrium? – discontinuous
change: long periods of time and then a
short burst of speciation
– Extinctions:
• Mass extinctions: where large numbers
of taxa become extinct all at once.
Darwinian Evolution Pros
• Natural Selection (“survival of the fittest”)
works
• Some organisms do seem to resemble
each other
• Change happens within a species
• DNA is the key component of all living
things
Darwinian Evolution Cons
• Theory does not provide a testable hypothesis
• Fossil record problems
– Huge gaps exist for “transition” species
– Fossil record can be “upside down”
• Structure evolution requires significant modifications for
proper functioning
• -- Longer arms require different muscular-skeletal
support
-- sensory: eyes, ears, nerves?
-- asexual to sexual mechanisms
* Some systems cannot evolve through single mutations;
they need many parts to function in unison at the same
time
-- Darwin’s “black box”
UNDERSTAND THIS: Darwinian evolution as
presented in the book would take HUGE amounts
of time. That is why it is essential that
evolutionists believe in an OLD EARTH!!! Without
billions of years available, the argument for
evolution would not be possible.
For Darwinian evolution to have happened, two
things had to happen:
1.
Appearance of living things from
lifeless chemicals
2.
Multiplication and diversity of all
species
Neither of these has ever been seen or have ever
been reproduced!
Fossils
• Any evidence of former life
– Can include actual or altered remains of
plants and animals
– Also less direct evidence such as leaf
imprints, dinosaur footprints and bat
droppings
• Knowledge of rocks containing fossils can
provide clues about their origins
Types of Fossils
1. Preserved whole organisms
– Must be protected from scavengers
and decomposers
•
•
•
•
Freezing
Entombment
Amber
Ash
2. Preserved hard parts
– More easily preserved
– Composed of calcium carbonate,
calcium phosphate, silica, chitin
•
Shells, bones, teeth, exoskeleton,
spores
Types of Fossils
3. Petrified fossils
– Formed by modification
of original chemicals
– Takes place over long
time
4. Fossils that are not
remains
– Footprints, tunnels,
nests, dung
Trilobites
Dinosaur Eggs
Crinoids
Fern Frond
Ashfalls Fossil Bed
Using Fossils to Determine the Order
of Geological Events
• Principle of succession
– Rocks can be placed in chronological position
based on fossils
• Index fossils
– Distinctive and widely distributed plant or animal
fossils
– Lived only briefly with a common extinction time
– Allow age correlations of exposed rock in different
locations
• Relative dating technique
• Used for sedimentary rock –not found in igneous or
metamorphic rock
Intermediate Fossils?
(Celancanth)
Taxonomy:
The science of naming and grouping organisms
• Modern system begun by
Carolus Linnaeus
• Bi-nominal system of nomencla
ture
Two name system:
– Genus
• Group of closely related species
– Specific epithet
• Identifies species within genus
• Placed organisms into groups
– Two kingdoms
• Plantae and Animalia
Modern System
• 3 Domains:
1. Archaea
Ancient bacteria
2. Eubacteria
Kingdom
Prokaryotes
Bacteria
3. Eucarya
Kingdoms
Protista – single cell
Fungi – multicellular, cell walls, nonphotosynthetic
Plantae – multicellular, cell walls,
photosynthetic
Animalia – multicellular, no cells walls,
non-photosynthetic
Protista
Fungi
Plantae
Animalia
8 Common Taxanomic Groups
• Domain (Eucarya)
Kingdom (Animalia)
Phylum (Chordata)
Class
(Vertebrata)
Order
(Primates)
Family
(Hominidae)
Genus
(Homo)
species
(sapiens)