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(5 BYA) Solar system
The solar system began to form and contained gas and dust. There was a dying star (supernova) that exploded and it made dust particles that eventually formed together and later made a dense spherical clould. -
(4.6BYA) Earth Forms
Earth began to form and grew by coliding with space debris. There was a big explosion in the universe, this is known as the Big Bang theory. When this occured all the matter and engery of space was contained at one point. Molecules from space may have affected life on earth. -
(4 BYA) Rocks & Crystals found
The oldest known rocks and crystals are about 4 billion years old. Inside the earth, there is a liquid core of molten rock and on the outside there is a hard crust. The crust is made up of rocks and minerals. This is how the rocks were found. -
(4 BYA) Organic Molecules accumulate.
Scientists infer that organic molecules began to accumulate about 4 billion years ago. Organic molecules are essential to life. Many of them are in the food we eat. It was important that these were found for those reasons. -
(3.5 BYA) -Fossils found
Fossils of stromatolites are as old as 3.5 billion years, according to scientests. Fossils were created many different ways; Freezing was one way, this means the preservation of ancient materials. Fossils are important because they are ancient remainders. -
(3 BYA) Photosynthetic activities found
According to scientists, photosynthetic forms of life were found 3 billion years ago. Chemical traces of photosynthetic activity is the oldest known fossil. -
(2.2 BYA) Earth fully formed
Scientists believe that 2.2 billion years ago, Earth probably appeared at it does today. Also, by this time, oxygen levels in the atmosphere increased dramatically. -
(2 BYA) O2 levels increased
By this time, O2 levels reached the levels they are today. Photochemical dissociation produced O2 levels approximately 1-2% current level. -
(2 BYA- 1.5 BYA) Aerobic prokaryotes begin.
Between 2 billion years ago and 1.5 billion years ago, the type of small aerobic prokaryotes were engulfed and began to live and reproduce inside a larger anaerobic prokaryote. -
(1 BYA) Ozone forms
One billion years ago, the ozone (O3) was formed. It protected organisms from harmful UV rays so they could exist on land. Our skin and hair are transparent to UV-B, but our DNA is not. UV-B can directly attack the DNA in our bodies and cause mutation, cancer, and reduction in crop yields. Therefore, the ozone layer is very important. -
(1600-1700) Franceso Redi
Redi did an experiment on flies to test his hypothesis, which was to see if flies generated spontaneously from rooting meat. -
(1700-1800) Lazzaro Spallanzani
Lazzaro Spallanzani did an experiment that tested the hypothesis of the spontaneous generation of microorganisms. Microorganisms formed not from the air but other mircroorganisms. -
(1900-Present) Lynn Margulis, Sidney Fox and Thomas Cech
Sidney Fox was the scientist who cloned huge amounts of research on the physical structures that might have help with the rise of the 1st cells. In 1938 Margulis proposed that early prokaryotic cells may have developed a mutally benefical realtionship. At high temperatures these gases may have formed simple organic compounds like amino acids.Then in the 1980's Thomas Cech found a type of RNA, that was in some unicellular eukaryotes, is able to act as a chemical catalyst. -
(1800-1900) Pasteur, Oparin, Urey and Miller
Pasteur was the scientist who created the curve neck flask that prevented soild particles from entering the body of the flask. Pasteur's experiment cleared up the confusion people who still believed in spontaneous generation had.
Oparin and Haldane thought that ammona was part of the early atmosphere.
Urey and Miller tested Oparin's hypothesis by setting up an experiment that contained of the Earth's early atmosphere and put them into a closed system.
