1. THE ORIGIN OF LIFE

2. THE FORMATION OF LIFE
This is highly theoretical but not a random guess – there has been lots of research
We know more about the conditions of early Earth than about how specific organisms evolved

3. 4.5-4.6 BILLION YEARS AGO- THE EARTH FORMS
No oxygen!
No oceans!
No organic molecules
No life!
The Earth was extremely hot
Lots of volcanoes
Lots of comets/meteors

4. THE EARLY ATMOSPHERE
Volcanoes spewed gases such as NH3, CH4, H2O (as a gas) and H2 into the air
No oxygen
About 4 billion years ago the Earth cooled enough for the gases to condense, forming the oceans

5. THE MILLER-UREY EXPERIMENT
Reproduced the conditions of early earth
When they heated a flask containing the molecules of Early Earth organic molecules formed within a day
Amino acids formed within a week

6. HOW DID THIS TURN INTO LIFE?
Lots of theories!
Each group will research 1 theory of their choice and share out

7. 3.5-3.9 BILLION YEARS AGO – LIFE!
Simple, single celled organisms that consumed organic molecules
Did not use oxygen and built up CO2 in the atmosphere
LOTS of competition so they likely evolved quickly

8. Autotrophic prokaryotes evolved
3.3 BILLION YEARS AGO
Autotrophic prokaryotes evolved
Bacteria that could photosynthesize
Huge survival advantage
Produced oxygen which dramatically changed the Earth’s atmosphere

9. THE OZONE LAYER FORMED
O2 from photosynthesis interacts with UV light to form the ozone layer
This prevented UV light from damaging living organisms
Can also be used for aerobic respiration

10. AEROBIC RESPIRATION EVOLVED
Mitochondria-like bacteria evolved
Use O2 in the atmosphere to more efficiently break down molecules
This allowed them to get more energy from food – another huge advantage in survival

11. ABOUT 1.5-2.1 BILLION YEARS AGO
The first eukaryotes formed (single celled)
Organisms with organelles
Endosymbiosis occurred

12. ABOUT 1 BILLION YEARS AGO
The first multi- cellular eukaryotes appear
Probably after the evolution of sexual reproduction
Thought to have possibly evolved from colonies of single celled organisms

13. A NOTE ABOUT MULTICELLULARITY
It has evolved several (around 13) times in the eukaryotic lineage
Plants and animals have different single- celled common ancestors

14. ABOUT 600 MILLION YEARS AGO
The first simple animals evolved in water

15. ABOUT 475 MILLION YEARS AGO
Plants colonized land
This paved the way for animals to come ashore
It only took insects about 75 million years to do it
And vertebrates about 115 million years
(So don’t complain about a 40 minute lecture )

16. ABOUT 200 MILLION YEARS AGO
Mammals evolved
Came about 160 million years after amphibians and about 100 million years after reptiles
But mammals evolved about 50 million years before birds
(and 70 million years before flowers)
Hadrocodium – the first mammal????

17. ABOUT 55 MILLION YEARS AGO
The first primates evolved
They were small, about the size of a squirrel

18. ABOUT 2.5 MILLION YEARS AGO
The first members of the homo genus appeared
Thought to be Homo Habilis but there is still a lot of debate about human evolution

19. ABOUT 200,000 YEARS AGO
The first Homo sapiens sapiens (humans) are thought to have evolved
Humans have existed for about 0.004% of Earth’s existence
And about 0.005% of the time life has existed
And 0.03% of the time animals have existed

23. WE BELIEVE ALL LIFE IS RELATED
1 tree of life
Based on:
A common genetic code
Same basic molecules in all living things (amino acids, proteins etc.)
Similar metabolic pathways

24. WE BELIEVE ALL EUKARYOTES ARE RELATED
Based on:
Similar membrane-bound organelles
A cytoskeleton organizing the cell
Linear chromosomes (compared to circular chromosomes of bacteria)

25. ORIGINS OF LIFE RESEARCH
Pick one of the hypotheses/models/theories
Create a relatively short presentation focused on:
A general description of the model
Who proposed it and when?
Evidence/support for it
Problems or arguments against it

26. POSSIBLE THEORIES/HYPOTHESES/MODELS
RNA world
Clay
Iron/Sulfide/Zinc
Extra-terrestrial
Hydrothermal vents
Bubbles
Metabolism first
Panspermia (extraterrestrial)
Something else you’ve heard of