1. 29.2
Explanation for Evolution

2. Darwin’s Work
• Charles Darwin studies natural
selection in the Galapagos Islands over
200 years ago
• He published a book on his finding and
made several important points
• Livings things over produce.
More offspring are produces than survive

3. 2. There is a variation among offspring.
A variations is a trait that makes an individual
different from others of its species
3. There is a struggle to survive
There are more living things than there are
resources to go around. This results in
competition. Competition is the struggle
among living things to get their needs for life,
such as food, water, shelter or mates

4. 4. Natural selection is always taking place
Individuals with less desirable traits are
less fit. Those with more desirable traits
are more fit and reproduce more. The
traits that make them more fit are the
ones that are passed on to new
generations.

5. Darwin knew this occurred very slowly
and led him to a theory called evolution
Evolution is the change in the heredity
features of a group of organisms over
time.
When a species changes over time the
term evolved, is used

6. Fossil Evidence
• Fossils are the remains of once living things
from ages past
• A fossil can be a print of a leaf, a footprint,
bones, an animal frozen in a glacier or an
insect trapped in hardened plant sap
• Scientists can compare things from the past
to things that are known today and record the
changes that have taken place

7. • Most fossils are from extinct organisms.
Extinct means no longer alive
• Many fossils are found in the sedimentary
rocks found in the earths crust
• Sedimentary rocks form from mud, sand and
fine particles and form at the bottom of seas.
• Animals die and settle into the bottom of
these waters and after millions of years form
into rock
• Fossils form into these rock layers and give
us a record of the types of living things on
earth at that time.

8. • By carbon dating scientists are able to
date the age of the fossils
• Fossils found at the bottom of
sedimentary rocks are the oldest.

9. • Other evidence
• Many embryo’s have common traits and have
common ancestry because of common DNA.
• Some species have vestigial structures, that
is structures that no longer serve a purpose.
• Examples in mammals include the appendix.
In humans it is not needed, but in rabbits it is
used to digest grass. The pink lump in the
corner of your eye is the remnant of a third
eye lid, such as those in frogs and other
amphibians

10. changes in fossils
similarities in embryos
Evidence of Evolution
gene code
vestigial structure