Spontaneous Generation

Origin of Life
What is Spontaneous
Generation?
The idea that living things could
arise from nonliving things.
Scientists performed controlled
experiments to learn more about
spontaneous generation.
Redi’s Experiment
th
(mid 17 century)
 Italian scientist Francesco Redi (16261697) observed and described the
different developmental forms of flies.
Redi’s Experiment
 Noticed that maggots seemed to appear
where adult flies had previously landed.
Redi questioned the common belief
that flies were generated
spontaneously from rotting meat.
In 1668 Redi conducted an
experiment to test his
hypothesis that meat kept
away from adult flies would
remain free of maggots.
 At about the same time that Redi
conducted his experiment, other
scientists began using a new
tool…
The Microscope
Who developed the first
microscope?
Anton von Leeuwenhoek
Microorganisms were discovered
using microscopes.
Many people at the time thought that
microorganisms arise spontaneously
from a “vital force” in the air.
Spallanzani’s Experiment
 In the 1700’s, an Italian scientist – Lazzaro
Spallanzani (1729-1799) designed an
experiment to test the hypothesis of
spontaneous generation of microorganisms.
Hypothesized that
microorganisms
formed not from the
air, but from other
microorganisms
Spallanzani’s opponents objected to his
method and disagreed with his
conclusions.
--------------------------------------------------They claimed he heated the experimental
flasks too long, destroying the “vital
force” in the air inside them. Air lacking
this force could not generate life.
Louis Pasteur (1822-1895)
 Cleared up the issue of spontaneous
generation of microorganisms.
The principle of BIOGENESIS
was accepted.
BIOGENESIS states that all living
things come from other living
things.