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The history of Life and earth. Early Ideas. Will rotting give rise to maggots ? Can mud produce live fish? Will a bag of wheat give birth to mice?. Spontaneous Generation . the idea that non-living material can produce life. Francesco Redi (1668). an Italian physician

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early ideas
Early Ideas
  • Will rotting give rise to maggots ?
  • Can mud produce live fish?
  • Will a bag of wheat give birth to mice?
spontaneous generation
Spontaneous Generation
  • the idea that non-living material can produce life
francesco redi 1668
Francesco Redi (1668)
  • an Italian physician
  • disproved the common belief that decaying meat produced maggots
  • performed a controlled experiment
  • convinced many scientists that maggots and large organisms did not arise by spontaneous generation.
Redi placed decaying meat in several covered and uncovered jars

Over time, maggots filled the open jars but not the covered ones.

This showed that only flies produce flies.


Although Redi disproved the spontaneous generation of large organisms, many scientists still believed that microorganisms must arise spontaneously

They believed there must be some vital force in the air that caused microorganisms to arise

louis pasteur 1800 s
Louis Pasteur (1800’s)
  • designed an experiment to disprove spontaneous generation of microorganisms
  • set up an experiment where air but no microorganisms were allowed to contact a broth that contained nutrients
who am i
Who AM I?
  • What’s wrong with you people…living things can not come from non living things. Living organisms don’t just spontaneously generate.
  • Francisco Redi
  • Results of Pasteur's experiment showed that:
    • Microorganisms do not simply arise in broth, even in the presence of air
    • Led to the idea of biogenesis

living things can only come from other living things


simple organic molecules
Simple Organic Molecules
  • simple organic molecules or molecules that contain carbon must have formed before the appearance of life
  • simple molecules must have been organized into complex organic molecules such as carbohydrates, proteins and nucleic acids
who am i1
Who Am I?
  • I think the energy from the sun, lightning, and Earth’s heat triggered chemical reactions to produce small organic molecules and a primordial soup in the oceans that formed the molecules of life.
  • Alex Oparin
who am i2
Who Am I?
  • They call me biogenesis man! I also helped to disproved spontaneous generation by showing that microorganisms also don’t spontaneously generate.
  • Louis Pasteur
alexander oparin 1930 s
Alexander Oparin (1930’s)
  • Russian scientist
  • hypothesized that life began in the oceans
  • suggested that energy from the sun, lightning, and Earth’s heat triggered chemical reactions to produce small organic molecules
  • Believed that rain washed the molecules that formed into the ocean to form a primordial soup.
stanley miller harold urey 1953
Stanley Miller & Harold Urey (1953)
  • American scientists
  • tested Oparin’s hypothesis
  • were the first to show that simple organic molecules could be made from inorganic compounds.
who am i3
Who Am I?
  • Its all about relationships you see…the eukaryotic needed the prokaryotic cells in order to come into existence
  • Lynn Margulis
evolution of cells
Evolution of Cells
  • First forms of life may have been prokaryotes
  • Organisms were most likely anaerobic
  • similar to Archaebacteria

- prokaryotes that live in harsh environments like hot springs

- do not require oxygen

- autotrophic

lynn margulis 1960 s
Lynn Margulis (1960’s)
  • American biologist
  • proposed the endosymbiont theory
  • theory explains how eukaryote cells may have come into existence
endosymbiont theory
Endosymbiont theory
  • eukaryotes evolved through a symbiotic relationship between ancient prokaryotes.

This theory explains the origin of chloroplasts and mitochondria.

Three properties of chloroplasts and mitochondria shared with prokaryotes: circular DNA, similar ribosomes, reproduced by fission.


Four Requirements of Life

  • Simple organic molecules, the building blocks of life.
  • A way to synthesize proteins from amino acids.
  • A coding system for replicating proteins – such as DNA.
  • A way to form cells from molecules - membranes
who am i4
Who Am I?
  • We believed that simple molecules came from simple inorganic compounds
  • Miller and Urey
knowledge check
Knowledge check

Which is an example of the theory of

spontaneous generation?

Tadpoles become frogs.

A starfish can grow from a severed arm.

Damp hay and corn create mice.

From a tiny acorn, an oak can grow.

knowledge check1
Knowledge check

Why do scientists believe that archea are

the closest relatives to Earth’s first cells?

They are eukaryotes.

They contain DNA.

They carry out photosynthesis.

They live in extreme environments.

knowledge check2
Knowledge Check

Who is the scientist who showed that microscopic life is not produced by spontaneous generation?

  • Francesco Redi
  • Stanley Miller
  • Louis Pasteur
  • Alexander Oparin
who am i5
Who Am I?
  • Our Earth is the way that it is because of the forces that have been place on it for long periods of time.
  • James Hutton
james hutton 1785
James Hutton (1785)
  • Proposed that Earth was shaped by geological forces that took place over extremely long periods of time.

He estimated the Earth to be

millions of years old. He wrote the "Theory of the


thomas malthus 1798
Thomas Malthus (1798)

The human population was growing faster than the space and food needed to provide for it. Natural disasters and forces of nature would solve the problem

who am i6
Who am I?
  • Giraffes now have long necks because they stretched over millions of years
  • Lamarack
jean baptiste lamarck 1809
Jean-Baptiste Lamarck (1809)
  • – principle of use and disuse
  • A giraffe acquired its long neck because its ancestor stretched higher and higher into the trees to reach leaves, and that the animal’s increasingly lengthened neck was passed on to its offspring.
  • Structures will change and “grow”or disappear be simply using or dis-using them
charles lyell 1833
Charles Lyell (1833)
  • Wrote Principles of Geology, made Darwin ask himself:

“If the earth can change over time, then why can’t the things on it?”

  • “ It must have taken life many, many years to change.”
charles darwin
Charles Darwin

What is a Theory? – well-supported testable explanation of phenomena that have occurred in the natural world

1859 Darwin published his book:

On the Origin of Species

“Life changes over time by the process of natural selection.”

natural selection ideas
Natural Selection Ideas
  • tendency toward overproduction of offspring
  • not all offspring produced will survive
  • variations exist in any population
  • variations are inherited
  • individuals better suited to their environment live longer & produce  more offspring than those less suited (survival of the fittest)
  • entire population will change as it becomes better adapted to its environment
who am i7
Who Am I?
  • We will run out of resources soon, so we better have some natural disasters to control our population.
  • Thomas Malthus
who am i8
Who AM I?
  • I am the man of evolution. People know me for y ideas on natural selection and survival of the fittest. I also loved traveling to the G. islands
  • Charles Darwin