Download The Theory of Evolution

The Theory of Evolution
Let’s Look at What Darwin was
Thinking
What is Evolution?
• Evolution is….
How Long is “A Change Over Time”?
• Individuals ____________ evolve.
• Populations ___________ evolve.
Who was Darwin?
• Started medical school
• Attended seminary
• Met up with a botanist; sailed on the HMS Beagle
at the age of 23
Volcanic Islands
http: Galapagos Island video
Darwin’s Tortoises
• Why do they look different on different islands?
Darwin’s Finches
• Why do they look different on different islands?
Darwin was Influenced by Others
• James Hutton: Earth has to be
more than just a few thousand
years old!!
Darwin was Influenced by Others
• Charles Lyell
Darwin was Influenced by Others
• Thomas Malthus: The human race will grow
faster than the supplies needed to support it
Darwin was Influenced by Others
• Lamarck, 1809: Inheritance of Acquired Characteristics
1. Living organisms acquired
characteristics that
helped them adapt and
survive.
2. Organisms then passed
these characteristics on
to the next generation
Lamarck’s Giraffes
Darwin was Influenced by Others
• Alfred Wallace, 1859: Came
to the same conclusions that
Darwin did.
Darwin was Influenced by Others
• Wallace studied the Malay Archipelago
Darwin’s “The Origin of Species”
• Published in 1859
• 3 Important Observations
– 1. Members within a species vary. They are not
all the same.
– 2. Much of this variation is inheritable.
– 3. There is a “struggle for existence.” More
members of a species are born than can be
supported by the environment.
Darwin’s 2 Important Conclusions
• 1. Because of the variations, some organisms
are better able to survive to reproductive age
and have offspring. (They are ‘fit.’)
• 2. Characteristics that make an organism “fit”
will tend to accumulate over time.
Natural Selection
• The traits being selected for contribute to an
organism’s fitness in its environment
• What drives natural selection?
• What makes natural selection possible?
Evolution: Descent with Modification
• Each living species has descended, with
changes, from other species over time.
• Darwin called this “descent with
modification.” We now call it Evolution.
Darwin’s Realizations
• All of these birds from the Galapagos were
actually finches
• They had all likely descended from a single
species originally from Ecuador
Darwin’s Realizations
• These similar looking
animals are found in widely
different locations.
• It is most likely they
evolved from different
ancestors but accumulated
similar adaptive features
Artificial Selection: Man’s Involvement
in Evolution
Evidence for Evolution
1. Fossil record
Evidence for Evolution
2. Homologous Structures
• Similar bone structure suggests a common ancestor
Evidence for Evolution
2. Homologous Structures
• Vestigial Structures
Evidence for Evolution
2. Homologous Structures
• Human Vestigial Structures
Evidence for Evolution
3. Similarities in Embryology
• It is scary how much we look like other animals!
Human Embryo
A Summary of Darwin’s Theory
• Individual organisms differs; some of these
differences are inheritable.
• Organisms produce more offspring than can
be supported.
• Organisms compete for limited resources.
• Individuals best suited for their environment
survive and reproduce.
• Those characteristics that help an organism
survive and reproduce are passed on to future
generations.