When, where, and how did life originate on earth? This is a question that has been on the minds of men for centuries. From the earliest civilizations to modern times, many theories and ideas have been put forth. While many of these beliefs have gone by the wayside, either because they have been proven untrue, or those who were once followers of a particular belief no longer exist, there are today three prevailing ideas that still exist among a large group of scientists: life began on another planet and via a meteor, or some other means, made its way to earth; life began here on earth as a heterotroph; or life had its beginnings on earth in the form of an autotroph.
Prior to the mid-1600s, many scientists believed that life was generated by means of spontaneous generation, that is life arose from nonliving material. Through experiments done by such scientists as Frencesco Redi, Louis Pasteur, and others the idea of life being generated in this manner was proven to be untrue. It is now known that life is generated exclusively from other living organisms, that is, biogenesis. The question today remains, how did that first bit of life come into being?
Although not accepted by many scientists today, the idea of panspermia, that is life arose elsewhere and somehow made it to earth was once touted by a number of scientists. Panspermia was not a new idea at the time, but it was popularized by the Swedish scientist Svante Arrhenius in the early 1900s. Another proponent of this idea was the British molecular biologist Francis Crick who put forth the idea of “directed panspermia”, that is the idea that the seeds of life didn’t just accidently arrive here on earth, but rather were sent here by intelligent beings on another planet. On the website Astrobio.net, the author states that Crick believed that “a technological civilization could direct panspermia by stocking a spacecraft with a genetic starter kit.” (Matsos). Crick believed that this race of creatures (we must assume that they also evolved over multiplied billions of years) intentionally sent some sort of bacteria that could survive the harsh realities of space in order to populate this distant planet. Most scientists tend to be critical of the idea of panspermia as it doesn’t answer the question of how life arose, but simply moves the question of its genesis to another planet.
A second idea of the origin of life is the belief that the first living organisms were heterotrophs, which began their existence here on earth. These organisms would have derived their nutritional needs from organic molecules in the waters where they lived. As these creatures devoured the existing organic molecules, it is proposed that the amount of nutrients available to them would eventually be depleted. In order for future generations to survive, it would be necessary for mutations to take place and the offspring which had acquired these mutations would be able to survive because they could consume other types of organisms. The problem with this theory though is that it has been scientifically proven over the years that mutations almost always lead to death or weaknesses in the organisms. Besides, this idea itself doesn’t answer the question about the origin of life, but rather just tries to explain how the first forms of life consumed their dinner.
A third idea is the belief that the first earthly organisms were autotrophs. Autotrophs would have been organisms that acquired their energy from inorganic materials. Many scientists believe that the earth was once in an extremely hot state. Based on the fact that many organisms, called chemoautotrophs, derive their nutrients from the energy released from inorganic chemical reactions, some scientists today believe that the ancestors of these chemoautotrophs were themselves able to derive nutrients from their thermal surroundings. Again, this theory, like all the rest do little to explain how the first forms of life originated, they simply make conjectures about how these simple forms of life may have existed.
The main problem with all of these ideas is that they have absolutely no way to explain the origin of whatever was here first. If one states that organism C came from organism B, it begs the question, then where did organism B come from? The only answer is that it came from organism A, but where did organism A come from? No matter how far back you go, there is always that same question, where did the very first organism come from? In the book Concepts in Biology, the authors state that “new living things come from other living things…but that does not answer …how the first living thing developed…life must have originated spontaneously from nonliving material at least once.” Which of course makes us ask once again: Where did that first nonliving material come from?
© 2018 Stephen Moore. All rights reserved.
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References
Enger, Eldon D., Frederick C. Ross, and David B. Bailey. Concepts in Biology. New York:McGraw-Hill, 2012
Matsos, Helen. “Francis Crick Remembered.” Astrobio.net 30 July 2004. 15 May 2012 http://www.astrobio.net/index.php?option=com_retrospection&task=detail&id=1107
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