Evolution by ewghwehws

VIEWS: 7 PAGES: 16

									The Origin of Life
Origins of Life:
◊ The origin of life remains a matter of
  speculation. We will look at four alternate
  views:
         • Panspermia
         • Undersea Thermal Vents
         • Primordial Soup
         • Creationism
Panspermia
 • Life’s origins did not
   originate on Earth, but
   originated elsewhere in
   the universe.
 • Proposes that cellular
   life reached Earth
   “seeded” inside a meteor
   which hit a long time
   ago.
Criticisms of Panspermia
Theory
 • The odds of an organism surviving inside a
   meteor for thousands of years are not
   high.
 • Unlikely that organisms would be able to
   withstand the high energy impacts of
   bodies into the Earth or other planetary
   objects.
Undersea Thermal Vents
• Life originated deep
  beneath the surface of
  the ocean at deep sea
  hydrothermal vents.
• These vents release hot
  gaseous substances from
  the center of the earth


 Found ecosystems thriving in the depths of the ocean.
 Because life had been found to exist where it previously
was thought unable to, many scientists began to ask
questions as to whether or not this was where life may
have originated on the earth.
Criticisms of Hydrothermal
Vent Theory
 • On the molecular level, the chances of life
   originating at deep sea thermal vents is not
   likely.
 • It is known that organic molecules are
   unstable at high temperatures, and are
   destroyed as quickly as they are produced.
   It has been estimated that life could not
   have arisen in the ocean unless the
   temperature was less than 25oC, or 77oF.
Primordial Soup
• The Primordial Soup Theory states that life began in a
  warm pond/ocean from a combination of chemicals
  that forms amino acids, which then make proteins.
  This is suppose to happen at least 3.8 billion to 3.55
  billion years ago.
• The basic building blocks of life (amino acids) came
  from simple molecule which formed in the
  atmosphere (without oxygen).
• This was then energized by lightning and the rain
  from the atmosphere created the "organic soup".
Abiogenesis - ・ Abiogenesis (Greek a-bio-genesis, "non
  biological origins") is the hypothetical generation of
  life from non-living matter. Today the term is primarily
  used to refer to hypotheses of the origin of life from a
  primordial soup.

Biogenesis - is the process of lifeforms producing other
   lifeforms.
         ◊e.g. a spider lays eggs, which form into spiders.
The Miller-Urey Experiment (1950s)
They mixed gases thought to
be present on primitive earth:
   Methane(CH4)
   Ammonia(NH3)
   Water(H2O)
   Hydrogen (H2)
   No Oxygen
They then electrically
sparked the mixture to signify
lightning. The results were
amino acids, the building
blocks of proteins.
Criticisms of Primordial Soup
 • Amino acids have to become protein
       •   a. 1 protein = 100amino acids of 20 varieties
       •   b. 10130 combinations of amino acids
       •   c. Hard to hit the right protein by accident
       •   d. Amino acids are building blocks, not the assembled structure
 • Early atmosphere contain different gases than those
   used by Miller/Urey (Experiments with true
   atmospheric gases did not produce abundant amino
   acids)
 • 2nd Law of Thermodynamics
       • a. System becomes less and less organized over time
       • b. Means amino acids cannot form protein spontaneously
         (more and more organized)
 • Primordial soup too dilute to achieve anything
       • a. Cannot spontaneously generate proteins
       • b. No mechanism to concentrate and make protein
Creationism
• The word "creationism" is used to
  describe all groups who believe
  that a supernatural being created
  the universe.

• Scientific Creationism - the belief
  that the account of creation in
  the early chapters of Genesis is
  scientifically as well as religiously
  valid and that it can be supported
  by scientific evidence apart from
  scriptural authority.
Creationism
 • Creationism is a broad category. Some forms of creationism
   include:
             ◊ Young Earth Creationism - literal belief of Genesis.
             ◊ Old Earth Creationism - no literal belief of Genesis.
             ◊ Intelligent design (ID) - believe that a "Designer"
               (God) is necessary to explain life's complexity.
             ◊ Evolutionary creationism - believe that God guides
               nature and evolution.
             ◊ Theistic evolution - believe that God is responsible
               for creating the universe and laws of science, and
               thus creating evolution.
Creationism
• There are other creation myths, not of Judeo-
  Christian origin:
          ◊Vedic Creationism - Believes the life and
            the universe have always existed (Hindu)
          ◊Raelian Creationism - Believe life was
            created by ET scientists.
          ◊Wingmakers - Modern myth centered on
            scientific discovery of human spiritual links
            to a creator (“James” from NYC)
Creation
 • There is no single creation
   story among Aboriginal
   peoples, who have a
   diverse mythology.
 • For example, among the
   First Nations peoples, eight
   unique stories of genesis
   exist and have been
   adapted in several forms:
   the earth diver, world
   parent, emergence,
   conflict, robbery, rebirth of
   corpse, two creators and
   their contests, and the
   brother myth.

								
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