1. Aim: Introduction to Evolution
Enter Date
Aim: Introduction to Evolution
Warm-up:
HW:

2. What is Evolution? Evolution
changes in living organisms over time
explains how modern organisms have descended from ancient organisms
Evolution!
Evolution!
Evolution!
Why do we accept this as a Scientific Principle?

3. What do we know? Biodiversity of Life on Earth
There are many different creatures on Earth
How do we know this?
OBSERVATION
Biodiversity of Life on Earth

4. What do we know? cells DNA Unity of Life on Earth
All creatures have common characteristics
How do we know this?
OBSERVATION
cells
DNA
Unity of Life on Earth

5. What do we know? Life is very old! The Earth is very old
How do we know this?
TESTING & OBSERVATION
Radioactive Dating
of the Rocks
Life is very old!

6. What do we know? Creatures have changed over time How do we know this?
OBSERVATION
Fossil Record

7. Primitive Earth Primitive earth was VERY different.
1. The atmosphere did not contain oxygen
2. There was an abundance of energy from lightning, heat, and UV rays
3. The temperature was super hot.
Not many things could live here. (Only heterotrophs)

8. Extremophiles
Scientists believe the first organisms on earth were heterotrophs.
They were mostly microscopic organisms like bacteria and viruses.
They were able to live in extremely harsh conditions.
Heterotrophs used anaerobic respiration and ate small organic molecules from the ocean.

9. Heterotroph Hypothesis
This theory explains how living things may have developed on the primitive earth.
According to this hypothesis, the first organisms were able to synthesize oxygen from carbon dioxide and sunlight.
ALSO known as PHOTOSYNTHESIS!

10. BUT THEN!!! One organism developed the ability to do photosynthesis!
All of the organic molecules in the ocean combined to form autotrophs.
Autotrophs used carbon dioxide and released oxygen into the air.

11. Aerobic Respiration These autotrophs gave the air oxygen
Now a new life form could evolve by breathing oxygen.
These are called aerobic.

12. What has the fossil record shown us?
Many creatures that lived in the past don’t exist today
Origin of new species

13. What has the fossil record shown us?
The creatures alive today haven’t always been around
Different species lived in the past

14. What has the fossil record shown us?
Many creatures in the past looked like living ones we see today
“Family Tree”
Relatives with similar, but not the same traits

15. Quick review, so far…. Evolution Many different species alive today
All life shares common characteristics
The Earth is very old
Life is very old
Life has changed over time
The changes have been little changes over long periods of time
Evolution
But how does this work?

16. Evolution explains Unity & Diversity
Only evolution explains both
unity of life
similarities between all living things
diversity of life
wide variety of different creatures on Earth
DNA