We may never know what exact
process lead to the origin of life on Earth.
Resolving this question may be as important as disproving
spontaneous generation (Pasteur)
Origins
Big Bang roughly 10-18 billion years ago
Formulation of Carbon and heavier elements in the first generation of
stars
Earth and Solar system slowly forms
Earth roughly 4.5 billion years old (uranium isotope dating)
Crust stabilizes by 3.9 billion years ago
Earliest fossils 3.6-3.7 billion years ago
Early atmosphere was reducing versus oxidizing atmosphere (lots of gasses
but not oxygen)
Current atmosphere is oxygen rich (Oxidizing) breaks down organic
molecules (like fire)
Spontaneous
generation (idea prevents medical
advance)
- most cultures believed that life could arise spontaneously from organic
matter
nematodes from horse
hairs, 40 BC Virgil gave a
recipe for growing bees artificially
- what causes disease? how transmitted???
-
Antony van Leeuwenhoek 1659 -
invents microscope observes
microorganisms in water
- von Helmont
proves that mice hatch from a dirty shirt
and wheat husks
- 1668
Francesco Redi - proves
maggots come from fly eggs not meat
- 1750
Spallanzani - used sterilized broth to disprove SD failed
- 1865
Pasteur - uses a simple glass apparatus to
finally disprove spontaneous generation setting a new course for medical
research
- Pasteurization of milk, vaccine for rabies
"Imagination should give wings to our
thoughts but we always need decisive
experimental proof, and when the moment comes to draw conclusions and to
interpret the gathered observations, imagination must be checked and
documented by the factual results of the experiment."
"Chance favors only the prepared mind."
Louis Pasteur 1822 - 1895
Joseph Lister
1866 - doctor uses hygienic techniques to reduce
infant mortality
- sterilizes surgical gear, treats wounds with carbolic acid
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