The Origin of Life

There are many theories about how life originated and the process life took in order to evolve to what we see on Earth today. Piecing it Together on page 247 indicates that millions of different species evolved from protocells via a detailed and long evolutionary process. Another theory, the Panspsermia Theory, suggests that life on Earth is derived from life on other planets. The idea is that organisms such as bacteria traveled to Earth via meteorites/asteroids (Panspermia Theory, n.d.). Evidence that supports the Panspermia Theory includes how bacteria and its spores are able to survive harsh environments, such as U.V. radiation and extreme temperatures. In addition, meteorites have been shown to contain not only bacteria, but some of bacteria's biological requirements such as amino acids and carbon (Panspermia Theory, n.d.; Duke University, n.d.). Another origin of life theory is that of the Hydrothermal Vent Theory. Hydrothermal vents are basically holes in the ocean floor that release extremely hot gas into the ocean, causing a gradient of water temperature from extremely hot to cool. The theory is that the temperature of the water surrounding the extreme hot water was optimal for the organic chemistry required to create and maintain life. The evidence that supports this theory is that there is indeed a thriving ecosystem within the warm water surrounding the hydrothermal vent. However, it is controversial (as all origin of life theories are) as to whether or not the organic chemistry could have occurred in this area in the exact correct way for life to begin (Duke University, n.d.). A third theory is the Prebiotic Earth Theory, which is a more general theory about the beginning of Earth and life on Earth. This theory describes the environment of space that allowed the formation of the sun and the earth. This theory suggests that the atmosphere of early Earth was reducing and contained CH4, NH3, H2. This mixture of gases is thought to be able to create biotic compounds that could lead to the creation of life. The evidence for this was supported by an experiment performed by Miller and Urey which used these gases in a closed system; however, now many scientists feel that early Earth actually had a neutral atmosphere which would not produce life (Duke University, n.d.).

Duke University. (n.d.). "Possible Sites for the Origin of Life." Retrieved July 28, 2010 from http://www.chem.duke.edu/~jds/cruise_chem/Exobiology/sites.html

Panspermia Theory. (n.d.). Retrieved July 28, 2010 from http://leiwenwu.tripod.com/panspermia.htm