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(5 BYA) The Formation of the Solar System
The Universe was full of swirling gas and dust, and some of it pulled together to form the Sun. Some of the remaining gas and dust collided together to form the planets, making the solar system. The solar system's arrangement and the relatively temperate sun it revolved around made planet Earth a potential place for life to develop. -
(4.6 BYA) Formation of Earth
Swirling elements and matter came together and fromed the planets, which included Earth. Earth's unique composition of elements, location within the solar system, and geological attributes made it the most likely planet to develop life. -
(4 BYA) Volcanoes and the Atmosphere
Volcanoes began to emitt gases which started to form the atmosphere. Rocks and the first crystals were formed as well. The atmosphere allowed life to develop on Earth and the formation of rocks and crystals led to the development of Earth's geology. Both of these contributed to Earth's ability to harbor life and allow it to thrive. -
(4 BYA) Formation of Life
Archaic single celled life forms begin to populate the planet (anaerobic heterotrophic prokaryotes). These are the first life forms to appear on the planet. Their development and ability to survive in early Earth's environment made them the roots of all other life on the planet. -
(3.5 BYA) First Stromatolites
Stromatolites first appear in the fossil record around this time, and they are rocky colonies formed by microorganisms, like cyanobacteria. These fossils show that single-celled organisms were abundant during this time period, and those organisms were critical to the development of life on Earth. They were cirtical to the development of life, aiding in the development of an oxygen-rich atmosphere and the transition to eukaryotic cells. -
(3 BYA) Photosynthesis
Photosynthetic forms of life first begin to appear during this time period. The development of photosynthetic life forms was critical to the development of life on Earth as a whole, as they continued to make the atmosphere more hospitable to less archaic life forms and photosynthetic organisms provide the basis for the majority of food chains on Earth today. -
(2.2 BYA) Eath Transforms
The Earth's geology and physical attributes became fairly similar to what they are today. This transition to a more hospitable environment fostered the development of new life forms and made Earth an ideal environment for complex organisms to grow. -
(2 BYA) Further elements for sustained life
The oxygen levels reached the levels thery are at today. The elements settled and photosyntesis of plants was already happening to create the oxygen. It affected all of the future organisms that needed oxygen to live including us. -
(1.5 BYA) Endosymbiosis
Endosymbiosis is believed to have occured around this time. Endosymbiosis is the process by which a larger, anaerobic cell would engulf, but not digest, a smaller aerobic cell and the two would develop a mutually beneficial relationship. This process is thought to have led to the development of eukaryotic cells. Eukaryotic cells are the cells that make up larger, more complex organisms today. -
(1 BYA) Formation of the Ozone layers
The Ozone was formed with the gases emitted from photosynthesis and also debris. This allowed more life to grow on the Earth because the Earth was now protected from the suns harmful UV rays. -
(1600-1700) Biogenesis
Redi's expiriment where he kept flies from rotting meat and proved that if they were kept away proved that life had to come from other life (maggots from flies). He did this becaus he was curious as to how life was created and from what, so he developed this expiriment. This affected the total idea of how life was created. Before this expiriment, the generally accepted idea was spontaneous generation, but now people realized that life had to come from other life. -
(1900-Present) Thomas Cech
Thomas Cech discovered the catalytic properties of RNA. His work was crucial to developing an understanding of RNA and how it works. By adding to people's knowledge of RNA, he allowed other scientists to discover even more about it and its vital function within cells. -
(1900-Present) Urey and Miller
Urey and Miller conducted an experiment that tested Oparin's hypothesis. Their test on the hypothetical possibillities of life's origin on Earth provided crucial evidence that supported Oparin's hypothesis. Their experiment and its findings greatly helped to solidify the argument that life could have developed in the beginning of Earth's history, and this early life gave rise to all other life on the planet. -
(1900-Present) Sidney Fox
Sidney Fox was a biologist who did extensive research on structures that led to the development of the first cells. Fox studied structures like microspheres and coacervates. Thanks to Fox's work, these two structures are now believed to have been the origins of the first single-celled cells. Our knowledge of this and the evidence that support this hypothesis all assist in our understanding of the first life on Earth. -
(1700-1800) Spallanzani
Spallanzani wanted to further Redi's theory, so he created an expiriment where he boiled broth and then sealed on flask, but left another open. He concluded that microorganisms did not come about spontaneously, and that they were carried by the air, but could be killed oif boiled. This furthered Redi's ideas and also lead to more expirimentation from others to prove this wrong. -
(1900-present) Oparin’s Hypothesis
Oparins hypothesis suggested that many organisms could have been synthesized with the right conditions in the early stages of Earth’s development, challenging widely held beliefs about evolution and the origin of life. This affected the previous beliefs of the world on how life came to be. -
(1900-Present) Radiometric Dating
Radiometric dating is a process that allows scientists to determine the age of organic materials by measuring the amounts of certain isotopes within the specimen. This technique allows us to date things like 1000-year old wood and organic materials that are hundreds of thousands of years old. This technique has allowed us to conduct extensive research on the age of fossils and artifacts, aiding scientists in their search for answers on the oirgins of life. -
(1900-Present) Lynn Margulis
Lynn Margulis is an American biologist who is famous for her work on early eukaryotic cells and the endosymbiotic theory. She challenged the scientific community by theorizing that eukaryotic cells developed through the process of endosymbiosis, as organelles were originally smaller, indepenedent organisms. Her theories were revolutionary and have become the accepted explanation for the origin of eukaryotic cells. -
(1600-1700) First Microscopes
The first microscopes were created which allowed people to see and better understand the functions and such of microscopic organisms including cells and bacteria. They were created so that people could understand more about microscopic things. This affect many things including the ways people thought of things. It changed their ideas because they now understood more. -
(1800-1900) Pasteur
Pasteur's experiment was a varied version of Spallanzani's experiment. Pasteur put a curved neck on his flask to show that even with air present, the brothj remained clear. Then when he broke the neck off, it became cloudy. This effectively proved all of the arguments against Spallanzani wrong and also eliminated the idea of spontaneous generation. He did this to prove the theory of biogenesis, and it affected the total idea of all biology, because it was a new theory.
