Life on Earth

Part I: Ambiogenesis
Orgins of Life

In recent weeks I have been thoroughly interested in the formation of life on planet Earth. Researching the wide variety of theories I was genuinely open minded, even looking at creationist arguments for a divine supernatural creator. These arguments lead me to discover the cornerstone in the creationist argument against evolution, which is, that life cannot appear from non-life. Thus, something  had to exist to generate new life. This argument, however compelling you may find it, led me to research the evidence of spontaneously forming organic lifeforms. I soon discovered the compelling theory of abiogenesis, which is the natural process by which organic life arose from non-living matter.

The earliest life on Earth existed at least 3.5 billion years ago, during the Eoarchean Era when the molten crust of the Earth had just begun to solidify. The earliest specific evidence of life is biogenic graphite, which is just a composition of carbon molecules found in 3.7 billion year old metasedimentary rock. Additional evidence comes from microbial mat fossils found in 3.48 billion year old sandstone discovered in Western Australia.

img2Now the hypotheses for how life originated is fiercely divided into a number of categories. Many approach the idea with the simple question of how self-replicating molecules came into existence. If we begin with the assumption that life originated on Earth, (Many believe that life could have begun with microbial life entering Earth via meteoroids or comets. This hypothesis is called Panspermia, and is main reason why interplanetary probes are thoroughly sterilized.) the study conducted by Miller-Urey demonstrate that most amino acids can be synthesized in conditions similar to early Earth.  Several catalysts have been examined as well, including exposure to radiation and lightening.

Other theories, such as the “Metabolism First” hypothesis state that initial chemical reactions involved the spontaneous formation of simple molecules such as acetate, a two-carbon compounded formed from carbon dioxide and water. The underlying core of the theory is that life began by the accumulation of simple organic molecules in favorable conditions.