1. How does Life Arise? 2 major theories:
NOT talking about how the first organism came about, but how living things are created.
2 major theories:
1. Abiogenesis – translates to…..?
“without life birth”
2. Biogenesis – translates to…..?
“life birth”

2. Abiogenesis
Early theory where people thought life came about by Spontaneous Generation
States that life can arise from non-living matter
Hence the meaning of “without life birth”
Mix rock with water…. Get a fish

3. Abiogenesis
Aristotle (300 B.C.) - saw fish in lake which had been completely dry and barren of all life.
Rain came and mixed with mud and…
PRESTO – instant life.
If Abiogenesis is true, it would mean that:
Maggots came from meat/rotting material
Mice came from hay
Crocodiles came from water
Theory was believed until about the 17th century
Why?

4. Biogenesis States that life can only arise from living matter
Francesco Redi (1600’s) – performed experiments with meat
Placed meat in jars with covers and without covers
Only the meat in jars without lids had maggots
Flies laid very tiny eggs on meat in open jars but couldn’t reach the meat in jars with lids

5. Biogenesis Louis Pasteur (1800’s)
Boiled meat broth to kill anything living in it
Put broth in special swan-necked flask
Let sit and broth just stayed clear (no bacteria growing)

6. Biogenesis Louis Pasteur (1800’s) Broke the neck of the flask
A day later the broth gets cloudy from bacteria growing in it…
Why did Pasteur get this result?