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(5 BYA) Solar System Forms
The solar system was a swirling mass of gas and dust.
Over time, most of the material was pulled together by gravity and formed the sun. the remaining debris circled the sun, collided, and formed planets. -
(4.6 BYA) Earth Forms
Earth began to form by colliding with space debris. -
(4 BYA) Ages are estimated with radiometric dating
The estimated age of Earth
Earth and other materials have had their ages estimated using radiometric dating and radioactive isotopes. -
(4 BYA) Earth's age estimated
700,000 times as long as the period of recorded history.
50 million times as long as the human lifespan. -
(3.5 BYA) Stromatolites are known
Fossils of stromatolites
are known. -
(3 BYA) Life becomes photosynthetic
Some forms of life had become photosynthetic. -
(2.2 BYA) Earth looks how it does today
Earth appeared as it does today. -
(2 BYA) O2 levels are reached
O2 levels reached today’s levels. -
(2 BYA) O2 was bombarded with sun rays.
O2 was bombarded with sun rays. -
(1.5 BYA) Prokaryotes are formed
Type of small aerobic prokaryote was engulfed by and began to live and reproduce inside a larger anaerbic prokar
yote. -
(1 BYA) Organisms are protected by ozone
Ozone (O3) formed – protected organisms from harmful UV rays so they could exist on land -
1600-1700
Francesco Redi does an experiment using raw meat, flies, and netting to work toward disproving spontaneous generation. -
(1665) Microscopes
Robert Hooke used an early light microscope in 1665. -
(1700-1800) Spallanzani
Spallanzani disproved theories about spontaneous generations by boiling broth and showing that it did not become cloudy when it was covered. This proved that the microorganisms had to come from other microorganisms and not the air. -
(1800-1900) Pesteur
Pesteur set up experiments using boiled broth to back up Spallanzani’s experiment with the microorganisms. -
(1800-1900) Biogenesis
Biogenesis was then a majorly accepted principle of biology instead of spontaneous generation. -
(1900- present) Cech
Thomas Cech found that a type of RNA found in unicellular in some eukaryotes is able to act as a chemical catalyst. -
(1900- present) Oparin and Haldane
Alexander I. Oparin and John B. S. Haldane hypothesized that the atmosphere contained ammonia NH3, H2, H2O, and compounds made of hydrogen and carbon. -
(1960) Margulis
Lynn Margulis hypothesised and proved that endosymbiosis caused the formation organelles in the 1960s. -
(1900- present) Miller and Urey
Stanley L. Miller and Harold C. Urey tested the hypothesis and found organic compounds such as amino acids. -
(1900- present) Fox
Fox did extensive research that on physical structures that may have given rise to the first cells.
