Charles Darwin and Evolution

download report

Transcript Charles Darwin and Evolution

Things you may not have
known about evolution:
Charles Darwin and Evolution
“from so simple a beginning, endless
forms most beautiful and most
wonderful have been, and are being,
evolved.” – Origin of Species
I. Darwin’s Travels
1. In 1831, Charles Darwin traveled on the HMS
Beagle (a ship) around the world from England.
One specific place he went was to the Galapagos
Islands off of Ecuador.
2. Along the way, he made observations of many
plants and animals and collected specimens. This
evidence led him to propose a revolutionary
hypothesis on evolution.
The Voyage of the Beagle
5 years
Evolution is basically change over
time. It is the process by which
modern organisms descended from
ancient ones.
II. Darwin’s Observations
He asked questions!
- Why aren’t there any rabbits in Australia
even though climate is right?
- Why are there no kangaroos in England?
- Why is there such variety in living things,
i.e. biological diversity.
- How are species so well suited to their
- Why had so many species disappeared?
- How are they related to living ones?
• Fossils would be the answer to many of his
questions. Fossils are the remains of ancient
 Some ancient fossils resemble modern living
 Some fossils didn’t look like ANYTHING
he’d seen before. WHAT HAPPENED?
 Why were there so many different types of
tortoises, finches etc. Why not just one type
since they all lived on the Galapagos Islands?
• –Islands are far apart w/ different climates,
different species.
The tortoises varied in predictable
ways from one island to another.
Shell shape and neck length could
identify the island the tortoise came
• The finches on the different island had
different beaks for different foods.
• The changes in beak shape were driven by
competition for food.
•Common ancestor???
III. Darwin’s
•These separate species of animals must have
come from one common ancestor!
IV. Ideas that Shaped Darwin’s
• A. At this time people thought:
1. World and life were created 1000 years
2. Nothing had changed since then!
V. New Ideas
A. Hutton and Lyell: Geologists
1. Through fossils and geologic
formations showed Earth was millions of
years old and that it was constantly changing
over time.
This all influenced Darwin…
• a. If Earth could change
over time, couldn’t living
• b. IF Earth were old (like
they are saying) it would
give time for organisms to
VI. Lamarck
A. His Ideas:
• Jean-Baptiste Lamarck said (before Darwin)
that by using something a lot or not using
something, an organism acquired or lost traits
during their life. These traits could be passed
on to the babies. “Use it or lose it” theory.
• Ex. Lamarck thought that if a giraffe stretched
its neck, it could pass this longer neck onto its
baby. (Acquired = gained)
• Ex. Or, say a swimmer builds up large strong
shoulders, he/she would pass large shoulders on
to their child.
• B. Lamarck didn’t quite get it right. He didn’t
know that an organism’s behavior doesn’t
influence what traits are passed on to offspring.
He did not know about genes.
• Still, he was one of the first to develop a
theory of evolution and recognize that organisms
are adapted to their environments. He paved the
way for Darwin!
VII. Darwin Speaks Out
A. On the Origin of Species
• He didn’t publish the book for 25 years! (A
little afraid of what would happen!) ….i.e.
“dangerous” idea.
• His theory was Natural Selection AKA “Survival
of the Fittest”
• In sum: the organisms best suited to their
environment will survive and reproduce.
1.Artificial Selection:
•Farmers, Breeders pick the “best” to
This Chihuahua mix and Great Dane show the
wide range of dog breed sizes created using
artificial selection.
Pigs are artificially selected by man to
produce the largest amount of meat.