Transcript Change Over Time - Westhampton Beach Elementary School

Change Over
Time …
Evolution
Objectives:
1. Define evolution.
2. How do we know the living
world has changed over time?
3. What can you learn from
fossils?
4. Define natural selection.
Why Change?
•
Changes in the environment can have
an impact on living organisms
Three options:
•
Adapt – change and find a way to
survive in the new situation
•
Move – migrate to a new location;
either temporarily or permanently
•
Extinction – failure to adapt
Evolution
•
The process of
biological change
over time
•
Organisms of the
present differ from
ancestors of the
past
Charles Darwin
Evolution – How do we know?
1. Some organisms evolve
or change very quickly
and can be observed
2. Examples: bacteria
and insects
3. Fossils are evidence of
past life
4. Examples: bones,
teeth, footprints,
shells, feather
impressions, etc.
Fossils
•
Early organisms were
simple in form
•
Organisms became
more complex over
time
•
The diversity of life
has increased over
time
•
New organisms appear
and others die off
(extinct)
Evolution – How do we know?
Equus – “modern horse”
300 cm tall
Today
Hyracotherium – “early horse”
20 cm tall
55 million years ago
Why do living things evolve?
•
Response to changes
in the environment
•
Ex. changes in climate,
vegetation, or
introduction of new
organisms
•
Some organisms have
variations that allow
them to adapt to
changes
•
Ex. genetic mutations
Natural Selection
•
Organisms with
favorable variations
are more likely to:
•
survive
•
reproduce
•
produce offspring
with these variations
Artificial Selection
Human beings have been using evolution for centuries!!
Thousands of years ago wolves were taken as pets by
humans. Each culture had specific traits they wanted
these animals to have. Today we have hundreds of
different types of dogs that are extremely different from
one another