An overview of theories of life.
In accordance with evolutionary biology, life originated about a billion years ago. During which time, the Earth’s atmosphere was very different than today. The ancient atmosphere of the earth contained extremely high levels of carbon dioxide and little free oxygen. It is believed that this carbon-based atmosphere is what gave rise to carbon-based life forms. Scientists since the 1950’s, have conducted experiments that prove that given this atmosphere amino acids could result in a spontaneous generation. It is from these simple carbon-based compounds that more complex arrangements were able to occur. These results were proteins, carbohydrates, lipids, phospholipids, and nucleotides. These components are the building blocks of RNA and DNA, which lead to proto-cells and on to cells.
The evidence for these claims can be found in geology as there is an abundance of carbon locked in the rocks dating back billions of years ago.
In an evaluation of this claim, scientists have asked themselves if the atmosphere was what they believed it to be billions of years ago. There is evidence found in fossil rocks, that the atmosphere was very different and the ultraviolet radiation was more prevalent on the surface of the earth a billion years ago. This would not have allowed life to occur as we know it but there are two factors which affect this outcome. First that the sun’s output was 30% less than it is today. As well, to have access to raw materials the photocells and protein chains would need to have been in the ocean. Under the sea these fledgling life forms would have escaped the dangerous radiation of the sun.
Another theory of the origin of life is the Panspermia Theory. The Panspermia Theory is a theory that life originated from outer space. The theory states that bacterial spores, which rode to earth by meteor and seeded the planet for life. It is theoretically possible that bacteria could have rode on comets locked in ice and would have survived the trip. This theory, however, is very difficult to accept because the chances of the bacteria even landing on the earth are infinitely bad. This is to say nothing of the chance of survival. This theory is derived out of the disbelief that life could have spontaneously generated and evolved to the state that it is today (Klyce, 2008). There is some evidence that life could have traveled to earth in this fashion since NASA has meteorites that came from Mars (Klyce, 2008).
Both theories have justifiable information but biological evolution that occurs on earth seems to have the most evidence to support its claims. Simply speaking evolution is measurable and science has seen adaptations in species and in viruses which gives credence to this theory. While it is true that meteors have traveled from one planet to another there is no real empirical evidence to support the claim that life could have originated in this manner.
Klyce, B. (2008). Introduction: More than Panspermia. Retrieved March 26, 2011, from Cosmic Ancestry: http://www.panspermia.com/intro.htm
Vincent Triola. Thu, Feb 04, 2021. Evolution & Panspermia Theories of the Origin of Life Retrieved from https://vincenttriola.com/blogs/ten-years-of-academic-writing/evolution-panspermia-theories-of-the-origin-of-life