Transcript 3.1 Origin of life

Evolution
• The development of life in geological time.
• Today evolution refers to the origin from
earlier life forms – the process that has
transformed life from its earliest beginning
to the vast diversity that has and does
exist today.
The Big Bang Theory
George
Lemaitre
First
proposed
‘big bang
theory’
Edwin
Hubble
All galaxies are
moving away
from us
The Hubble Telescope
3.9 billion years old
Where did life
come from?
Special Creation
•Life created by a
super natural being
at a particular time
Archbishop
Ussher
• 1654
• Life began on
earth at 9am,
23rd October,
4004 BC
• He based this
on
calculations
form the bible
William Paley
(1802)
• The fact that
such
complicated
things exist is
evidence for the
existence of a
creator!
Panspermai
• Life arrived form outer space
Comet storms
Fred
Hoyle
Life originated in
outer space and
came to earth
riding on light
beams
Svente Arrhenius
• Life originated
in the form of
spores and
was then
driven through
space by the
pressure of
light from the
sun.
Watson and Crick
• Crick – life
has evolved
twice.
• Once from
molecules to
intelligent
people
elsewhere.
• Once from
bacteria to
humans
Evidence
• Experiments have shown that when
ammonia, methane and carbon dioxide
are mixed with ice crystals in a vacuum
and UV light applied – hundreds of organic
molecules are formed.
• Presence of bacteria in meteorites
• Survival of bacteria in space
20 million year old Bee
Bacterai found in the resin were still
alive!
Cosmozoan Theory
Life arrived from outer space
• UFO’s
• Cave drawings of dinosaurs
• Kangaroos in SA
Britney
Spears
• Alien?
Spontaneous Generation
Aristotle (384BC-322BC)
• Believed that
certain particles
contained an
‘Active ingredient’
which could
produce life
Van Helmont (1577-1644)
• Recipe for spontaneous generation of
mice
•
•
•
•
Dirty shirt
Dark cupboard
Wheat grains
Active ingredient - sweat
Francisco Redi
• This experiment
asked questions
about spontaneous
generation
Pasteur
• Disproved
the idea of
spontaneous
generation
(1860)
Biochemical Evolution
• The formation of organic molecules from
inorganic material
Oparin – The Russian
J.B.S.
Haldane
The Brit
Jupiter
• Atmosphere
•
•
•
•
Methane
Ammonia
Hydrogen
Water
vapour
• CO2
Miller and Urey
Miller and Ureys
Experiment 1953
Fred Hoyle
• Life assembling
from inorganic
substances is –
• “as improbable as
a tornado blowing
through a junk yard
and assembling a
747”
Protobionts
Protobionts
• Proto – First
• Biont – life form
• These are specialized droplets whose internal
chemical characteristics differ markedly form
their surroundings.
• Capable of growth by engulfing other droplets
• These were probably the precursors to
prokaryotes
• RNA could provide means of transferring
information
Bacteria – Clostridium tatani
First life forms appear on earth
around 3.5 billion years ago
Prokaryote
Bacteria - Prokaryotes
So how do
we get from
Prokaryotes
to
Eukaryotes?
Endosymbiotic Theory
Amoeba – Protist
First Eukaryotes around 2.1 billion
years ago
Euglena
• Could
chloroplasts have
once been free
living
prokaryotes?
Paramecium - Protist
Were mitochondria once free
living prokaryotes
Theories for the origin of life
•
•
•
•
•
•
Special creation
Panspermia
Cosmozoan
Stready State
Biochemical Evolution
Spontaneous
Modern science evaluates theories in many
ways. For a theory to be scientifically
credible it must:
–
–
–
–
fit with the known facts
Overlap with other known scientific theories
Lead to testable predictions
Not rely on supernatural explanations
So which fit with scientific theory
•
•
•
•
•
•
Special creation
Panspermia
Cosmozoan
Stready State
Biochemical Evolution
Spontaneous
– fit with the known facts
– Overlap with other
known scientific
theories
– Lead to testable
predictions
– Not rely on
supernatural
explanations