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(5 BYA) Formation of the Solar System
Our Solar system was a swirling mass of gas and dust at this point and time. Soon, many objects and particles in space became larger and larger creating a center of the system and a belt of asteroids and particles constantly colliding and growing. -
(4.6 BYA) Creation of planets and Satellites
About 4.6 BYA, planets and satellies were created with reoccurring collisions that released large portions of energy. This created the planets of today although they were physically different looking and functioning. For instance, Mars may have had water covering almost its entire surface, while Earth was covered in molten lava and full of enourmous volcanic eruptions. -
(4 BYA) Formation of the Earth
Earth was formed at about this time, 4 billion years ago.
The archaea are a related group of unicellular organisms that thrive under extreme conditions. Archaea are similar to the type of living organisms that populated the Earth four billion years ago. These are the most primitivie life forms known to man. -
(3.5 BYA) Stromatolites formed
Lynbgya cells often grew in colonies and form layered structures called stromatolites. Many fossils of stromatolites are as old as 3.5 billion years of age. -
(3 BYA) Photosynthetic Plants Formed
Some forms of life advanced and became photosynthetic by three billion years ago. This meant that many organisms could now not only thrive off of the sun for warmth and light, but to also physically create energy for themselves as well as make food for other creatures. -
(2.2 BYA) Earth appears modern
By this time, Earth's many catastrophic and extreme natural storms died down. Therefore, about 2.2 billion years ago, Earth probably appeared much as it does today. -
(2 BYA) O2 levels reached normal levels
On Earth, the atmosphere developed, and O2 levels reached modern day's standard levels. -
(1.5 BYA) The Ozone began to form
It took a billion or more years for oxygen gas levels to reach today’s levels. Oxygen eventually reached the upper part of the atmosphere where sunlight hit it. Some wavelengths of sunlight can split O2 to form highly reactive O. These O atoms reacted with O2 atoms to form O3, or ozone. -
(1 BYA) The Ozone became formed enough for life to exist
Ozone (O3) formed – protected organisms from harmful UV rays so they could exist on land -
(1665) Light Microscope was used
The light microscope was used in 1665 by English scientist Robert Hooke. This was a significant invention because it allowed you to use optical lenses to magnify objects by bending light rays. Hooke first used this when he looked at thin slices of cork. He then saw little boxes in the cork and tree stems, roots, and ferns he looked at. These were dead plant cells he was seeing. The microscope also helped reveal that the world has many tiny creatures, including simple microorganisms -
(1600-1700) Spontaneous Generation proved wrong
• Redi observed flies flies and meat. He saw that rotting meat kept away from flies could not produce new flies. He also saw that maggots only appeared on the meat left out in the open. This showed that flies come only from eggs. Therefore, spontaneous generation was disproved. -
(1600-1700) Radiometric Dating first used
Radiometric dating is a way of establishing the age of materials. You use mass number, and half lifes. It also shows isotopes and their radioactive decay. This measurement method enables humans to measure very old objects such as the Earth. -
(1700-1800) Spallanzani's Experiment occured
• Spallanzani’s experiment was with broth and microorganisms. He had a sealed and open flask with broth in them. The sealed flask stayed clear while the open flask became cloudy. This helped to prove that microorganisms wouldn’t grow in broth that was heated and then sealed. He then inferred that microorganisms do not arise spontaneously, they are carried in the air. -
(!900's) Miller and Urey's experiment
Miller and Urey performed an experiment using Oparin’s hypothesis as a starting point. Their experiment then went on to produce a variety of organic compounds including amino acids. -
(1900's) Sydney Fox
Sydney Fox did work on the physical structures they may have given rise to the first cells. These include microspheres and coacervates -
(1900's) Thomas Cech
Thomas Cech found that a of RNA found in some unicellular eukaryotes is able to act as a chemical catalyst, similar to enzymes. He called these Ribozymes. -
(1900's) Lynn Margulis
Lynn Margulis said that endosymbiosis is how organelles arose, and that is now the excepted explanation for how eukaryotes arose. -
(1800-1900) Pasteur's Experiment
• Pasteur’s experiment used a variation of Spallanzani’s design to support that microorganisms are carried in the air and DO NOT arise by spontaneous generation. -
(1900's) Oparins hypothesis
• Oparin’s hypothesis said that hydrogen, water vapor and compunds made of hydrogen and carbon(methane) could form simple organic compounds like amino acids. They could then enter complex chemical reactions fueled by energy from lightning and ultraviolet light, these could ultimately result in the macromolecules essential to life, such as proteins.
