Transcript Presentation

Spontaneous Generation,
Evolution, and a Few
Scientists
Let’s do it..
Spontaneous Generation or
Abiogenesis
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The idea that life could arise from nonliving matter
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People used to think that beetles came
from dung and maggots came from meat
left standing in the open for days
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Today, we know that this is not true
Francesco Redi
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An Italian physician
Produced an experiment that disproved the idea of
sponataneous generation
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He placed meat in uncovered and covered jars and let
them sit for a few days
Flies could not get to the meat in the covered jars, so no
maggots were produced, however the flies were able to
get to the meat in the uncovered jars and maggots were
present after a few days
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His conclusion – Flies produce maggots, not the meat.
Spontaneous Generation did not exist.
His experiment
John Needham
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An English scientist
Used Anton van Leewenhoek’s discovery of
“animalcules” (microscopic organisms) to attack Redi’s
work.
He believed that spontaneous generation could exist
under the right conditions.
Needham took a bottle of gravy, sealed and heated it,
and a few days later.. The gravy was teeming with
microscopic organisms.
His conclusion – the gravy produced life. Spontaneous
Generation did exist.
Why would he heat the gravy?
His experiment
Lazzaro Spallanzani
Obviously he’s an Italian scholar read about the work of
Redi and Needham
 He believed that Needham did not heat his “gravy”
enough to kill whatever was already present in the
gravy.
 He duplicated Needham’s experiment with the exception
of boiling the gravy, rather than just heating it.
 He also had another jar left open to the air.
 The jar that was boiled, no life was present!
 The jar left open was teeming with microscopic
organisms
 His conclusion – Spontaneous Generation did not exist
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Spallanzani
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His experiment was
the same as
Needham’s with the
exception of what?
___________________
Louis Pasteur
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On into the 1800’s, scientist argued that how could life exist in a jar
sealed from the air.. No oxygen would be allowed in a sealed off
environment.
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So Pasteur created a curved neck flask.
He placed a solution in the flask, boiled it, and the flask remained
open to the air.
After a year, no microscopic organisms were in the solution.
He broke the curved neck flask’s neck and almost immediately, the
solution became present with microscopic life
His conclusion – Spontaneous Generation did not and could not
exist.
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Curved Neck Flask
Other contributions..
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Vaccination for the masses
– First vaccine for rabies
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The germ theory
– that microorganisms cause diseases
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Pasteurization
– makes food and beverages safe for
consumption
– And many others..
Evolution
Change over time.. Not man from
monkeys!
Evolution
It is defined by the simple phrase “change
over time.”
 It’s a process by which modern organisms
have descended from ancient organisms
 There are many scientists included in the
evolutionary discussion, but none more so
than Charles Darwin.
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Charles Darwin
His observations led to a revolutionary
theory about the way life changes over
time.
 An English scientist
 In 1831, he set sail on the H.M.S. Beagle
around the world.
 Darwin conducted a large amount of his
studies on the Galapagos Islands.
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Galapagos
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Darwin noticed
differences between the
beaks of finches and the
shells of tortoises in the
different islands of the
Galapagos.
He notes that what once
was one species had
evolved into different
species suited to live in
their specific environment
Finches
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As you can see, the
finches, over time,
developed a beak that
best suit their survival
on each particular
island of the
Galapogos.
The Origin of Species
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Was a book that
Darwin published that
shocked the world
and everything it
knew about life,
especially from a
religious standpoint.
Thomas Robert Malthus
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English scientist
Wrote a passage entitled
Essay on the Principle of
Population in 1798 that
helped Darwin formulate
his idea of natural
selection.
Noted for the first time
that nature produced far
more offspring that can
survive.
Alfred Russell Wallace
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British naturalist
Introduced the concept of
warning coloration in
animals, and the Wallace
effect, a hypothesis on
how natural selection
could contribute to
speciation.
All these ideas helped
Darwin to publish his own
thoughts on natural
selection.
Jean Baptiste de Lamarck
French naturalist
 Published a theory of
the inheritance of
acquired traits.
 One of the first to
explain how
organisms change
over time
 Also discussed “use
and disuse” theory
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Sir Charles Lyell
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British geologist
In his final volume of the
Principles of Geology, he
explained that processes
occurring now have
shaped Earth’s geological
features over long
periods of time.
Had an influence on
Darwin’s ideas.
Is this evolution?
You decide..