1. Chapter 29
EVOLUTION

2. 29-1 Changes in Living Things
• Objectives:
• 1. Give examples of how adaptations
help organisms survive
• 2. Explain how changes in life-form
occur
• 3. Describe the classification and
evolution of primates and humans

3. Adaptation
• An adaptation is a trait that allows living
things to survive in it’s surroundings
• Examples:
– Color
– Long legs
– Webbed feet
– Claws

4. Natural Selection
• Natural Selection is the process in which
something in a living things surroundings
determines if it will or will not survive to have
offspring
• Something in nature does the selecting
• Living things that are suited to their
surrounding will survive and pass their traits
on to their offspring.
• If they are not suited, then thy will not
reproduce and there will be no offspring

5. Mutations
• A mutation is a change in the DNA
code.
• Since traits are controlled by genes,
then adaptations are controlled by
genes
• Not all mutations are helpful and help
with survival

6. • Mutations are natural events and may be
helpful, harmful or have no effect at all. They
can occur in all living things
• Examples:
– A deer born with a white coat no longer blends in
with its surroundings. It can be seen more easily
by its enemies and may be eaten. It does not
pass its new trait on to its offspring
– A deer is born with longer legs which allows it to
run faster and get away from its enemies. It is not
eaten and can pass on this trait to its offspring so
more deer with longer legs are born

7. Species Formation
• A species is a group of living things that
can breed with with others of the same
species and form fertile offspring
• Fertile means able to reproduce by
forming an egg or sperm cells
• Only members of the same species can
breed and form offspring

8. • If a natural barrier, such as a wide river,
was created, animals on either side
could not swim cross and breed with
each other.
• Over time the two groups would
gradually become different because
their environments are different
• In time, each group becomes a new
species

9. • Charles Darwin discovered this on his
exploration of the Galapagos Islands.
• He discovered several species of Finches
with different types of beaks
• Each Finch lived on an island and did not
breed with the birds on another island
• Over time each Finch species developed a
different beak adapted to eating the specific
seeds found on the island because they did
not come in contact with each other

10. Events that can lead to the
development of a new species
1. A barrier is formed that separates members
of a species, such as a flood, mountains,
glacier or lava flow
2. The animals found them selves living in
different environments
3. Groups began to show different traits
because of natural selection
4. Over time the two groups became different
and if brought back together again they would
not be able to breed and have fertile offspring

11. Primates and Human
Evolution
• The classification of humans is:
• Phylum: Chordate - Class: Mammal -
Order: Primate
Primates include monkeys, apes and humans
• Primates are mammals with eyes that face
forward, a well developed cerebrum and
thumbs that can be used for grasping
• Humanlike ancestors first appeared around 3
million years ago.

12. • These ancestors walk upright, but were
much shorter than modern humans.
• Several different humanlike species
evolved, but they became extinct
• Two groups of homo sapiens lived on
earth. One was called Neanderthal, but
it became extinct
• The other developed into modern
humans of today