Early Earth Evolution
What was the first life on Earth?
If we link all the different
phylogenic trees we get…
• the tree of life - a giant phylogenic tree that
links all life to one common ancestor
Questions to Answer, or not.
• What is the common ancestor of all life?
• Where does present day life come from?
• How did it first form?
There were two
competing theories.
• abiogenesis - a theory that life comes from
non-living things
• biogenesis - a theory that life comes from life
Luis Pasteur • scientist that disproved spontaneous
generation or abiogenesis leaving biogenesis
Miller & Ulrey • two scientists
that did a early
Earth
experiments and
determined that
organic
molecules can
form
spontaneously if
the conditions
are correct
Which cell is the simplest and probably
first on the Earth?
• prokaryote - a single-celled organism lacking a
nucleus or membrane bound organelles
• eukaryote - an organism whose cells contain a
nucleus and membrane bound organelles
The first cell is prokaryotic.
• The early earth had no
oxygen.
What kind of chemical reactions would a
cell do with no oxygen present?
• anaerobic - a process that does not require
oxygen
• aerobic - a process that requires oxygen
Where would they get energy?
Hint: There is no oxygen on the Earth!
• heterotroph - an organism that obtains its
energy by feeding on other living things
(consumers)
• autotroph - a self-feeding organism that
obtains its energy from inorganic sources
(producers) and produces oxygen as a by
product
The first cell was probably a
1. prokaryotic, anaerobic, heterotrophic cells
Then photosynthesis evolved
1. prokaryotic, anaerobic, heterotrophic cells
2. prokaryotic, autotrophic, photosynthetic cells
• How do we know? Rusty rocks.
Photosynthesis produced oxygen
1. prokaryotic, anaerobic, heterotrophic cells
2. prokaryotic, autotrophic, photosynthetic cells
3. prokaryotic, aerobic cells
O2
Cells combined in symbiosis
1. prokaryotic,
anaerobic,
heterotrophic cells
2. prokaryotic,
autotrophic,
photosynthetic
cells
3. prokaryotic,
aerobic cells
4. Eukaryotic cells
Cells live together
1.
2.
3.
4.
5.
prokaryotic, anaerobic, heterotrophic cells
prokaryotic, autotrophic, photosynthetic cells
prokaryotic, aerobic cells
Eukaryotic cells
Colonies, eukaryotic cells
Cells live together
1.
2.
3.
4.
5.
6.
prokaryotic, anaerobic, heterotrophic cells
prokaryotic, autotrophic, photosynthetic cells
prokaryotic, aerobic cells
Eukaryotic cells
Colonies, eukaryotic cells
Eukaryotic Colonies with Cell Specialization,
tissues
The early earth tree of life.
Let’s draw it.