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(5 Billion Years Ago) Solar System
The solar system was a swirlling mass of gas and dust. -
(4.6 Billion Years Ago) Earth and Sun are Born
Gas and dust pulled together to form the sun and earth began to form colliding space debris. -
(4 Billlion Years Ago) Atmosphere
Volcanoes emmitted gas, forming earth's atmosphere. -
(4 Billion Years Ago) Cellular Life
Cellular life that resembled archea first populated the earth. -
(3.5 Billion Years Ago) Fossils
Fossils were foundof stromatolietes made of Lynbgya Cells. -
(3 Billion Years Ago) Photosythetic Life
Photosythetic life forms, and an example is cyana bacteria. -
(2.2 Billion Years Ago) Similar Earth
Earth's apperance was very similar as it is today. However O2 levels were not breathable yet. -
(2 Billion Years Ago) O2
O2 levels reached today's amount. -
(1.5 Billion Years Ago) Aerobic Prokaryote
Aerobic prokaryotes lived and produced inside anerobic prokaryotes. -
(1 Billion Years Ago) Ozone Formed
Ozone formed and protected organisms from harmful UV rays so they could exist on land. -
(1600-1700) No Spontaneous Generation
Francesco Redi performed an experiment on flies and the effect on meat when the flies come in contact with it (1600's). He discoverd that eggs and maggots did not appear on open meat. This experiment contributed to the discovery that spontaneous generation does not exist. -
(1800-1900) Louis Pasteur
Louis Pasteur resolved the problems of Spallanzain's experiment by making a curved-neck flask that allowed the air outside and inside the flask to mix, but prevented solid particles from entering the flask. The broth in the curved flasks remained clear but when the curved necks were broken the broth became cloudy. This experiment showed spontaneous generation to be incorrect. -
(1953) Urey and Miller
Stanley L. Miller and his professor Harold C. Urey set up an experiment modeled after Oparin's hypothesis. The experiment included a chamber containing the gases Oparin assumed were present in early Earth's atmosphere. Electric sparks supplied energy to drive chemical reactions in the chamber. Miller and Urey's experiment produced a variety of organic compounds like amino acids. -
(1970's-Present) Thomas Cech
In the 1980's, Thomas Cech realized that a type of RNA found in some unicellular eukaryotes
is able to perform as a chemical catalyst, similar to an enzyme. Cech called this unique type of RNA a ribosyme. Ribosymes can trigger specific chemical reactions in eukaryotes. Cech's studies have lead to other discoveries dealing with RNA, such as its vital role in DNA replication -
() Lynn Margulis
Lynn Margulis proposed that early prokaryotic cells may have developed a mutually beneficial relationship. -
Radiometric Dating
Radiometric dating is a method of establishing the age of materials. This technique requires the knowledge of atomic numbers for given elements and involves counting and examining isotopes. -
(1700-1800) Microorganisms are not Carried in the Air
Lazzaro Spallanzani performed an experiment using chicken broth in the 1700's . Spallanzani hypothesised that microorganisms do no arise spontaneously, but arise in the air. However, his hypothesis was not upheld. Microorganisms do not arise spontaneously, and they are not carried in the air. -
(1600's) First Microscopes
At approximately the time of Francesco Redi's meat and fly experiment in the 1600's, scientists began using the earliest models of the microscope. The first microscopes lead scientists to the discovery that there is a countless amount of microscopic organisms on earth. This new knowledge caused scientists to conclude that microorganisms arise spontaneously via a “vital force” in the air. -
(1920s) Oparin's Hypothesis
Oparin thought that the early atmosphere contained ammonia, hydrogen gas, water vapor, and compounds made of hydrogen and carbon. Oparin hypothesized that at high temperatures, these gases might have formed simple organic compounds. -
(1970) Other Organic Compound Ideas
Other scientists like Sidney Fox) believe that organic compounds could have been carried in by space from fallen meteorites. Also, if there are debris made up of organic compounds in space then, organic compounds could have been accumulated on the surface of early earth. Fox performed detailed research on physical structures that may have been related to the cells of earth's first organisms (ex: microspheres and coacervates).
