-
(5 BYA) Solar system was beginning to form
The solar system was a swirling mass of gas and dust. It was the beginning of the creation of our world. -
Period: to
History of the Earth
-
(4.6BYA) Earths Early Growth
The Earth begins to grow larger as gravity pulls debris in towards the center of gravity. It begins to take on a spherical shape, and its many layers of crust begin to form, one example being its core. -
(4 BYA) Earth is created
The earth is created by the debris from space. Its shape now makes it recognizable as a planet. It takes on characteristics that make it possible for early cells to live on it. -
(4 BYA) Cells are created
Early forms of anaerobic and heterotrophic cells begin to inhabit the earth. These are the first forms of life on earth. They pave the way for the future of evolution. -
(3.5 BYA) Stromalites arise
Colonies of cells, called stromalites, begin to arise on earth. These are the beginning of the first multi-cellular beings, that will eventually evolve into organisms. -
(3 BYA) Photosynthetic cells arise
Forms of cells that use photosynthesis to survive begin to arise. These are the first plant cells, and allow plant life to begin to grow on earth. -
(2.2 BYA) Earth develops similar to as it is today.
Earths contents, as well as the life on it, begin to become similar to how we know earth today. -
( 2 BYA) Oxygen levels reached todays levels.
Oxygen levels begin to rise, and this allows for many new types of cells that use oxygen for energy to arise as well. These are the cells that will eventually be used in the first oxygen-breathing organisms. -
(1.5 BYA) Prokaryotes grow inside of larger prokaryotes
Prokaryotes begin to develop and live inside of other prokaryotes. These begin to form larger organisms with complex internal functions. -
( 1 BYA) Ozone layer is formed
The ozone layer is formed. It protected early organisms from harmful UV rays so that they could exist on the land on earth. -
(1665) Invention of first Microscopes
In 1665, Robert Hooke studied nature by using a light microscope, which was just invented around this time. This microscope could magnify objects to a size much bigger than what the thing being studied actually is. This allowed people to get a better understanding of what is earth made up of, and also what microorganisms live here. -
(1700's) Spallanzani's Experiment
Spallanzani boiled chicken broth inside two flasks to kill all living things inside of them. One of the flasks was left open while the other one was sealed off. The open flask was cloudy, while the closed flask was clear. This proved that microorganisms would not grow inside of flasks that were closed off. -
(mid 1900's) Fox's Research
Sidney Fox did a lot of research on the physical structures of that may have made the first cells possible. These cell-like structures were randomly formed after solutions of simple organic chemicals were added. The structures that were formed were microspheres (sphere shaped structures that are composed of protein molecules) and coacervates (collection of droplets that are composed of different types of molecule) -
(early 1980's) Thomas Cech's Findings
In the early 1980's, Thomas Cech found that a type of RNA in some unicellular eukaryotes can act as a chemical catalyst. Cech appointed the word ribozyme for an RNA molecule that can act as a catalyst and can promote a type of chemical reaction. -
(mid-late 1900's) Lynn Margulis
Recently, Lynn Margulis has come up with the idea that early prokaryotes had a beneficial relationship with the evolution of eukaryotic cells. He believes that a small aerobic prokaryote was engulfed by anaerobic prokaryote. Inside this bigger prokaryote, the small prokaryote would live and reproduce. This theory, if true, could be how eukaryotic cells formed. -
(1668) Redi's Experiment
Redi put a piece of rotten meat in two control groups where the meat was exposed to the air and maggots. The experimental group had a net on top that shielded maggots from entering. This proving that all things come from other living things (biogenesis) and living things do not arise from non-living things (spontaneous generation). -
(mid 1800's) Pasteur's Experiment
Pasteur used a variation of Spallanzani's design to support that microorganisms are carried in the air and do NOT arise by spontaneous generation. He boiled broth inside of a curved neck, closed off flask, and let it sit for one year. After a year had passed, it remained clear. He then broke off the neck of the flask, and after one day, the broth had become cloudy. This proved that microorganisms cannot possibly be spontaneously generated. -
(1920's) Oparin's Hypothesis
Oparin, along with his partner Haldane, believed that the early atmosphere contained ammonia, hydrogen gas, water vapor, and compounds made of hydrogen and carbon (methane). Oparin thought at these high temperatures, these gases might have formed simple organic compounds, like amino acids. Oparin thought that a series of reactions would have resulted in the macromolecules essential to live, like proteins. -
(1950) Radiometric Dating
At the turn of the 20th century, scientists began to work on radiometric dating, but it was not until the 1940's when radioactive dating made significant progress. Radiometric dating is a way of establishing the age of materials. By looking at the different parts of an object, scientists can determine when the object was "born." -
(1953) Miller's and Urey's Experiment
Miller and Urey based an experiment off of Oparin's hypothesis. They had an apparatus that included a chamber that contained all of the gases that Oparin said was present in young Earth's atmosphere. As these gases circulated, in the chamber, electric sparks (that were considered a substitute for lightning, gave energy to supply chemical reactions. This experiment produced many organic molecules, like amino acids.
