Life’s Diversity
through Evolution
Science vs. Religion
What is science based on?
 Science is based on OBSERVABLE
evidence.
 What is religion based on?
 Religion is based on FAITH.

– By definition, faith is something that is not
observable.

Since they are 2 different “fields,” they are
not competing with each other
Religious Scientists?

“My religion consists of a humble
admiration of the illimitable superior spirit
who reveals himself in the slight details
we are able to perceive with our frail and
feeble mind.”
– Albert Einstein (1879 - 1955)

“Science without religion is lame, religion
without science is blind.”
– Albert Einstein (1879 - 1955), "Science,
Philosophy and Religion: a Symposium", 1941
Religious Scientists?

“Not only does God play dice, but... he
sometimes throws them where they cannot be
seen.”
– Stephen Hawking

“In my view, there is no conflict in being a
rigorous scientist and a person who believes in a
God who takes a personal interest in each one
of us. Science’s domain is to explore nature.
God’s domain is in the spiritual world, a realm
not possible to explore with the tools and
language of science. It must be examined with
the heart, mind and soul.”
– Francis Collins, Director of Human Genome Project
Evolution is a Theory

Theory Defined: “scientific principle to
explain phenomena: a set of facts,
propositions, or principles analyzed in their
relation to one another and used,
especially in science, to explain
phenomena”
– MSN Encarta, http://encarta.msn.com/dictionary_/theory.html

Evolution is as much a theory as…
– Cell theory: biology
– Atomic theory: chemistry
– Plate tectonic theory: geology
A Final Quote
“Be opinionated,
just not
ignorant.”
Evolution

The theory that organisms on Earth have
changed over time is known as evolution.

Charles Darwin (1809-1882) is the man
who contributed more to our
understanding of evolution than any other
individual.
Charles Darwin




English naturalist (1809-1882)
1831, Darwin took a job as a
naturalist on the HMS Beagle
– Went on a 5-year scientific
journey around the world
He collected many biological and
fossil specimens
– Combined with his previous and
subsequent observations
Published On the Origin of Species
by Natural Selection in 1859
– These ideas are a basic unifying
theme of biology today
– Without evolution, biology
doesn’t make as much sense
He realized that he had never seen many of
these organisms and the diversity of life on
Earth was enormous!
Darwin questioned
“Where did all of these different life forms come
from?”
EX: Darwin collected 68 species of beetles from
Brazil in just a few hours while on shore.
Darwin also
discovered many
fossils of organisms
that no longer existed
today. This lead to
other questions,
 “Where did all these
organisms go? And
why did they
disappear?”

Fitness
Darwin observed that many plants and animals
had parts and displayed behaviors that helped
them survive.
 Traits and behaviors that will help organisms
survive and reproduce in their environment give
those organisms greater fitness (ability to
survive and reproduce).
 Those organisms that are most fit will survive
and reproduce more often than those organisms
who are “less” fit.
 Became known as “survival of the fittest.”

– Darwin did not use this phrase, it came about later &
may cause misconceptions…
Fitness
Darwin argued that increased
fitness arises from adaptations.
 Certain adaptations allow
organisms to become better
suited to their environment, and
thus better able to survive and
reproduce.
 Adaptations can be physical or
behavioral


Does “struggle for existence”
mean only the biggest,
strongest animals survive?
What types of characteristics
increases an organisms chance
of surviving?
Summary of Darwin’s Idea

There is variation between individuals.
Summary of Darwin’s Idea

Organisms tend to
have more offspring
than can possibly
survive, so there is
competition among
the offspring for a
limited amount of
resources
Summary of Darwin’s Idea
Organisms compete for limited resources
 There is a struggle for existence

Summary of Darwin’s Idea

Those organisms that
are best suited for
their environment
(most fit) will survive
and pass on their
genes.
Darwin’s Theory of Evolution
Darwin developed evolution by natural
selection
 Compared the process of natural selection
in nature vs. artificial selection used by
people. He used this comparison to
develop a hypothesis to explain how
evolution occurs.

Using artificial selection a breeder can produce plants
and animals that look very different from their
ancestors. Artificial selection uses the variation nature
provides.
How does horse racing relate to selective breeding?
Darwin’s Origin of Species




He filled notebooks with
ideas about species
diversity & the process of
evolution.
His beliefs challenged the
fundamental ideas of that
time (species don’t
change).
Darwin was very reluctant
to publish his book due to
his fear of what the public
would think.
Are their any scientific
topics today that are
controversial?
Origin of Species

1858, a naturalist name Alfred Wallace sent him
a letter describing evolution. He had been
working in Malaysia and come to the same
conclusions Darwin did.

Darwin had been working on his theory and the
evidence to support it for 20 years. Darwin
published the Origin of Species in 1859, 23 years
after his trip.
Why do you think Darwin waited to publish his
book?
Origin of Species

His book did two things:
1. Proposed a mechanism
for evolution (natural
selection)
2. Evidence showing it
had been taking place for
millions of years and
continues to take place
Descent with Modification

Over long periods of time,
natural selection will start
to produce organisms
with different structures
or organisms that occupy
different niches or
habitats. Because of this,
species today look
different from their
ancestors.
Geological Evolution
– James Hutton (1788) proposed that
rain, wind, temperature, and natural
disasters shaped the valleys, mountains,
and rocks over extremely long periods
of time
– Charles Lyell (1830) contributed to this
by adding that current observations of
volcanic eruptions and other natural
disasters shows that Hutton was correct
in assuming the Earth was older than
originally predicted
Acceptance of Geological Evolution
Important to Darwin because it
established an OLD Earth
 Darwin’s theory of evolution required lots
of time
 Another important influence: Thomas
Malthus

– Observed that humans were being born at a
faster rate than they were dying
– War, famine, and disease control populations
– These observations provided enough curiosity
for Darwin to delve deep into his theory of
Natural Selection
humans evolve
First placental mammals
Flowering plants dominant
First birds
1st dinosaurs
First reptiles
First seed plants
First amphibians
First vertebrates
First invertebrates
eukaryotes
prokaryotes
Life evolves
Dating Techniques
Geologic Record
– Hypothetical library of all the known
geological processes on Earth
– Determined through inference and
dating methods
 Relative Dating (hee hee)
– Sediments are constantly being laid
down.
– Over time, many layers form
– If a fossil is in a layer below a different
fossil, it is older than that fossil

Radiometric Dating

Radiometric Dating
– Radioactive isotopes decay and form new
isotopes - the rate this happens is called
the isotope’s half life
– Ex: Potassium-40 decays to argon-40 and
has a half life of 1.3 billion years
 Half a sample will decay to argon-40 in
1.3 billion years
 So if there are equal amounts of
potassium-40 and argon-40 in an area,
the sample has been in place 1.3 billion
years
– Carbon 14 has a half life of only 70,000
years for more recent sample dating
Review
1.
2.
3.
4.
How does the geologic record help us?
What use is relative dating?
What is radiometric dating?
Why are different isotopes used in
radiometric dating?
Evidence for Evolution

Fossil Record
– A hypothetical “library”
of all the fossils
collected around the
world

Fossils show changes
throughout time
– 99 percent of all
animals are now
extinct
– Fossil record shows
ancestors with similar
characteristics
Embryology

Study of embryos and the
relationships that exist between
different species
Evidence for Evolution: Embryology
Many species share features in the young
embryos
– Ex: Mammals, reptiles, birds and fish all have
a tail and pharyngeal pouches (develop into
different respiratory systems)
Evidence For Evolution: Anatomy

Homologous Structures are structural features with
a common evolutionary origin
– Ex: whale forelimb, crocodile forelimb, bird wing, human
forelimb all look the same
– Can you think of other examples?

Analogous Structures are body parts or organisms
that do not have a common evolutionary origin but
are similar in function
– Bird, bat and butterfly wings
– Show how organisms adapt to different ways of life and
different conditions
Homologous Structures
Structure and function between species is
the same
Analogous Structures
Functions are the same between species;
structures are different
http://evolution.berkeley.edu/evolibrary/article/similarity_hs_01
Evidence for Evolution

Vestigial Structures
are body structures
that no longer serve
their original purpose,
but was probably
useful to an ancestor
– Ex: human appendix,
pelvic bone in baleen
whale, “tail” in
humans, some
human’s ability to
wiggle their ears
Vestigial Structures
Evidence shows the organ was once used, but
not any longer
Evidence for Evolution
Biochemistry
 Nearly all organisms
share DNA, ATP, and
many enzymes
among their
biochemical molecules
 Organisms that share
more similar
enzymes, DNA
sequences, etc. are
more closely related

Review
1.
2.
3.
4.
5.
6.
How did Darwin come up with his ides for natural
selection?
Some snakes have vestigial legs. Why is this
considered evidence for evolution?
Explain how adaptations such as camouflage help
species survive.
How do homologous structures provide evidence for
evolution?
Why did birds and bats both get wings?
A parasite that lives in red blood cells causes the
disease called malaria. In recent years, new strains of
the parasite have appeared that are resistant to the
drugs used to treat the disease. Explain how this could
be an example of natural selection occurring.