READ: Histroy of Life on Earth
6. Origin of Life on Earch
Origin of Life on Earth
There is good evidence that life has probably existed on Earth for most of Earth’s history. Some of the oldest fossils of life forms on Earth are at least 3.5 billion year old fossils of blue green algae found in Australia (Figure below).
Some of the oldest fossils on earth are stromolites, made of algae and a kind of bacteria, found along the coast of Australia.
The next step is to determine exactly how life formed billions of years ago. First, scientists need to know what the environment was like 3.5 to 4 billion years ago; they need to know what kinds of materials were available then that could have been involved in the creation of life. Scientists believe the early earth contained no oxygen gas, but did contain other gases, including nitrogen, carbon dioxide, carbon monoxide, water vapor, hydrogen sulfide and probably a few others.
Life from Random Reactions
Today, we have evidence that life on Earth came from random reactions between chemical compounds that formed molecules; in a series of random steps, these molecules created proteins and nucleic acids (RNA or DNA), and then cells. We know that the ingredients for life (the building blocks of life), were present at the beginning of Earth’s history. Some chemicals were in water and volcanic gases. Other chemicals would have come from meteorites in space. Energy to drive chemical reactions was provided by volcanic eruptions and lightening. Keep in mind that this process may have taken as much as 1 billion years. Our understanding of how life originated on Earth is developing gradually (Figure below).
Some clues to the origins of life on Earth come from studying the early life forms that developed in hot springs, such as the Grand Prismatic Spring at Yellowstone National Park. This spring is approximately 250 feet by 300 feet wide.
CK-12 Foundation, Biology. http://creativecommons.org/licenses/by-nc-sa/3.0/