1. WARM UP
Three brothers share a family sport:
A non-stop marathon
The oldest one is fat and short
And trudges slowly on
The middle brother's tall and slim
And keeps a steady pace
The youngest runs just like the wind,
Speeding through the race
"He's young in years, we let him run,"
The other brothers say
"'Cause though he's surely number one,
He's second, in a way.“
What is this object?

2. CHAPTER 6: CHANGES OVER TIME
Section 1: Darwin’s Theory

3. DARWIN’S BACKGROUND
 Born in England, 1809
 Studied Medicine at Edinburgh
University
 Transferred to Cambridge University
 Studied to be a Minister
Library of Congress, Prints and
Photographs Division [reproduction
number, e.g., LC-USZ61-104].

4. DARWIN’S EXPEDITION - 1831
 Hired as Naturalist on H.M.S. Beagle
 Sailed on Five Year Scientific Expedition
 Down East Coast of South America
 Up Pacific Coast to Galapagos Islands
 Made Stops on Mainland and Islands
 Observed Variety of Life and Habitats

5. DARWIN’S OBSERVATIONS

6. DARWIN’S OBSERVATIONS
 While traveling Darwin studied the things around
him during the course of his travels. Darwin
observed the diversity of living things, the remains
of ancient organisms, and the characteristics of
organisms on the Galapagos Islands.
 What is diversity?

7. DARWIN’S OBSERVATIONS
 There are over 1.7 million species of organisms on
Earth.
 A species is a group of similar organisms that can
mate with each other and produce fertile offspring.
 While traveling Darwin found the bones of dead
animals. These bones are called fossils. Some of
these fossils confused Darwin because they were
bigger then they should have been. Darwin wanted
to know why these animals were smaller now.
 A fossil is the preserved remains or traces of an
organism that lived in the past.

8. DARWIN’S OBSERVATIONS

9. GALAPAGOS ORGANISMS
 Notice how isolated the Galapagos Islands are.

10. GALAPAGOS ORGANISMS
 When Darwin was in the Galapagos Islands he
noticed many different life forms. Some of the
animals he had seen before were much different
then they were back in England.
 After noticing these differences Darwin began to
compare the animals found in the Galapagos
Islands to those found elsewhere. Darwin found
many similarities between these animals and ones
found in South America.
 Why was there this similarity?

11. GALAPAGOS ORGANISMS
 The animals in South America weren’t identical, for
example, the animals in South America had smaller
claws compared to the ones in the Galapagos
Islands.
 Darwin believed that some of the species found in
the Galapagos Islands had actually come from the
mainland of South America.
 He believed that over time, the animals on the
islands changed and became different then the
ones on the mainland.

12. GALAPAGOS ORGANISMS
 The differences between animals wasn’t just
between the mainland and the islands. There were
even differences between animals on one island
and the next.
 The size and shape of bird’s beaks differed
depending on which island they were located on.
 When Darwin looked at the beaks and the location
he found that the beak suited the location perfectly.
The bird’s beaks of that area were made to eat the
food found in that location.

13. GALAPAGOS ORGANISMS

14. GALAPAGOS ORGANISMS
 The shape of a beak is an example of one type of
adaptation.
 An adaptation is a trait that helps an organism
survive and reproduce.
 What are some examples of adaptations?

15. EVOLUTION
 When Darwin returned to England after his voyage
he continued studying the things he had observed
during his trip.
 Darwin finally came to the conclusion that plants or
animals that arrived on the Galapagos Islands
faced conditions that were different from those on
the mainland. Perhaps, Darwin hypothesized, the
species gradually changed over many generations
and became better adapted to the new conditions.

16. EVOLUTION
 Evolution is the gradual change in species over
time.

17. EVOLUTION
 Darwin’s beliefs are called the scientific theory of
evolution.
 A scientific theory is a well tested concept that
explains a wide range of observations.
 Darwin studied other living things to help him
understand how evolution might occur. One thing
he studied was the offspring of animals produced
by selective breeding.

18. EVOLUTION
 According to the theory of evolution, two processes
are necessary for populations to change over time.
These are mutations and natural selection.
 Natural Selection is the process by which
individuals that are adapted to their environment
are more likely to survive and reproduce than other
members of the same species.
 Darwin described his research in a book entitled
The Origin of Species.

19. EVOLUTION
 Proposed Evolution Resulting from Natural Selection:
 Organisms Produce Many Offspring
 Competition for Food, Territory, Mates, etc.
 Those With Best Traits Survive
 Organisms Change Over Many Generations
 Time Frame: Millions of Years

20. EVOLUTION
 The different ways natural selection occur are:
 Overproduction – there are too many offspring to
survive
 Variations – animals have different abilities
 Competition – animals compete with one another to
survive
 Selection – some variations make animals better suited
to an environment
 Environmental change – a change in environment can
make it easier or harder for an animal to survive
 Genes and natural selection – there can be certain
mutations or traits inherited that make survival harder
for an animal

21. EVOLUTION
 A variation is any difference between individuals of
the same species. Certain species might eat meat
where others only eat plants.
 Darwin believed that over a long period of time
natural selection can lead to change. Helpful
variations may gradually accumulate (add up) in a
species, while unfavorable (unwanted) ones may
disappear.

22. SCIENCE HUMOR