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(5 BYA) Beginning of Our Solar System
Solar system began to form as a swirling mass of dust and gas. As time went on most of the mass gravitated toward the center creating the sun. -
(4.6 BYA) Beginning Formation of Earth
Earth began to form and grew by colliding with space debris, while Volcanoes emitted gas, forming an atmosphere. -
(4 BYA) Formation of Oldest Rocks
Formation of oldest know rocks and crystals and organic molecules began to accumulate. Methods of establishing the age of materials include the techniques known as radiometric dating. -
(4BYA) Production of Methane
Methanosarcina barkeri produces methane during metablosim. Archaea are thought to be similar to the types of cellular life that first populated Earth about 4BYA. -
(3.5 BYA) First Photosynthesis
Lynbgya cells, unicellular, prhotosynthetic prokaryotes, often grew in colonies and form layered structures called stromatolites. Fossils of stromatolites as old as 3.5 BYA are known, like the one displayed in this picture. This marked the beginning of photosyntehsis. Photosynthesis is vital to life on earth, because from it we get all our energy. -
(3BYA) The First Bacteria
The blue-green bacteria was formed which was believed to be the first bacteria which could perform photosynthesis, so leading to the great oxygen poisoning of 3 billion years ago. They formed a symbiosis with fungi to create lichen, which was believed to be the first living thing to live on land . -
(2.2 BYA) Earth Now
By 2.2 BYA, Earth probably appeared much as it is today. The atmosphere was very similar to it is now and most of the organic material has been formed. -
(2 BYA) Oxygen
O2 levels reached today's levels. The level reached is essicential to the growth of more advanced life forms. -
(2BYA-1.5BYA) Endosymbiosis Theory
Small aerobic prokaryote started to be prodcued and live inside of larger, anaerobic prokaryote. The large eukaryotes provided a beneficial environment and the prokaryote provided a method of energy synthesis. These later evolved into mitochondria. Mitochondria are essencial to human life today because they prodcue most of the energy in the body. This theory is called endosymbiosis. -
(1 BYA) Formation of Ozone
Ozone (O3) formed – protected organisms from harmful UV rays by absorbing them so they could exist on land. Ozone is the resultant of electrical storms that changes O2 into O3. -
(1700's) Lazarro Spallanzani
Lazarro Spallanzani began using a new tool - the microscope. He created an experiment and tested the hypothesis of the spontaneous generation of microorganisms. He realized microorganisms formed from each other, not from air. He placed broth in flasks and boiled them, killing the "vital force" and placed a cork on one of them. The corked flask remained clear where the uncorked flask grew cloudy. He did not disprove spontaneous generation, but further showed its flaws. -
(1920's) Soviet Alexander I and John Haldane
Soviet Alexander I and John Haldane(pictured) tried to find the answer to the question: how and where were the elements assembled into organic compounds on Earth? According to Oparin, at high temeratures, the gases might have formed simple organic compounds, such as amino acids. -
(1953) MIller-Urey's experiment
Miller and Urey set up an experiment using Oparin’s hypothesis. The had a chamber which contained the gases Oparin hypothesized in Earth’s early atmosphere. As gases circulated sparks of electricity supplied energy to drive reactions.Their experiment supplied a variety of new compounds. This is significant because it provided an origin of many organic compounds. -
(1970's) Meteorite
A broad mixture of organic compounds was found in a newly fallen meteorite. Since the meteorite was recovered before it was contaminated with organic compounds from Earth, these compounds much have formed in space. Thus, organic compounds from space could have accumulated on the surface of early Earth. Thomas Cech discovered that RNA could itself cut strands of RNA, which showed that life could have started as RNA in the 1970's also. -
(1600's) Francesco Redi
Francesco Redi noticed the different forms of flies and how maggots acted in the control jars versus the experimental jars. Redi was not able to completely refute spontaneous generation, but he was able to set in motion the questioning of legitimacy. Redis experiment let us study biogenesis like we do today. In Redis experiment he placed veil in six jars. He covered half of the jars with gauze, allowing air in but not outside organisms. Jars with no gauze had flies, and jars with contained none. -
(1800's) Louis Pasteur
Louis Pasteur created an experiment to answer objections to Spallanzani’s experiment (1700’s). In his experiment he made a curve-necked flask that allowed the air inside the flask to mix with the air outside the flask. The curved flask prevented solid particles from entering the body of the flask. He proved spontaneous generation was a false theory and that there are microorganisms in the air. -
(1950's) Lyn Margulis
Scientists used similar experiments to that of the Miller-Urey experiment(pictured), to test and revise hypotheses about the origin of simple organic compounds. Including combining many chemicals and compounds to form products like ATP and amino acids. Lynn Margulis was best known for her theory on the origin of eukaryotic organelles, and her contributions to the endosymbiotic theory, which is now generally accepted for how certain organelles were formed.
