Origin Of Life

Scientists have been continuously presented with questions regarding the mystery that is life. What is life, and how did it get started? Their responses to these questions has varied over the years as advances in technology have led to new evidence being brought in from a ranging variety of fields.

In the summer of 1993, J. William Schopf, a paleobiologist reportedly found fossilized imprints of microbial communities between layers of rock that were 3.5 billion years old. This, along with other evidence indicated that life was well established only a billion years after earth's formation, which is a faster evolution than previously thought (Time, 1993, p.40). This belief that life evolved ever so quickly, induced scientists to attempt to create real life in the lab. The goal was to simulate the earliest organism in existence.

Theories for the origin of life has been around since the beginning of civilization. However, It was Charles Darwin who first introduced a biologically possible theory that is still intact today. Darwin suggested that life grew in a "warm little pond" of organic chemicals that, over a long period of time, gave life to the first organisms. As this theory evolved, the pond became an ocean. In a breakthrough experiment conducted by Stanley Miller in 1953, the first reasonable experimental evidence for Darwin's theory was developed. This evidence lay in a glass jar, in which a simplified version of earth in its infancy was created. Using water, ammonia, hydrogen and electrical discharge, Miller created organic chemicals, including a large quantity of amino acids. Although Miller's experiment presented the building blocks of proteins, many current researchers believe that a larger molecule - RNA - came before proteins. Meanwhile older fossils and organisms in oceanic hot springs contradict Darwin's vision of a peaceful evolution.

Around 4.5 billion years ago, the solar system was composed of merely gas and dust. Planets were created by the collision of small objects, which in turn caused the earth to become a molten ball. A billion years after the formation of this new planet, the gravitational fields that existed, attracted many kinds of free-floating junk. Icy comets, meteorites and asteroids, spiralled down like megaton bombs (Time, 1993, p.42). Christopher Chyba, a planetary scientist noted that, if any of the asteroids that struck earth those billions of years ago were at its largest size, all living things would have been wiped out.

The question remains, how could life have emerged and survived with all the asteroids? To answer this question, researchers have searched into the great depths of the ocean where they have come across strange, chimney-like structures that sit atop cracks in the ocean floor, known as hydrothermal vents, that lead to subterranean chambers of molten rock (Time, 1993, p.42). The result is an underwater geyser, which is a spring that discharges hot water and steam. Fifteen years ago, with the aid of submarines, scientists had the opportunity to explore environments they never imagined existed. They discovered many strange organisms and found that the sulfur-eating microorganisms found around the vents are the closest living link to the first creatures on earth (Time, 1993, p.42). This "hot world" hypothesis has been accepted by many. Norman Pace, a microbiologist stated that hydrothermal vents were much more common billions of years ago as the earths crust was still young and prone to cracking. Geochemist, Everett Shock calculates that organisms receive more nutrients at higher temperatures. But, whether life originated in the vents, or just migrated their, is yet to be seen.

According to Stanley Miller's famous experiment, life could easily be formed from gases in the atmosphere, which were previously believed to formulate the primitive earth. If this were the case, the earth would originally be cold, thus iron, not having melted yet, would have remained near the surface, absorbing oxygen and preventing carbon dioxide from forming. Nitrogen and carbon in the atmosphere could react with hydrogen and form the methane and ammonia in the Miller experiment (Time, 1993, p.43). However, beliefs about the violent collisions during the earth's birth, prevent such a theory to be true as the extreme heat caused by such collisions would cause the iron to melt and therefore creating an atmosphere of CO2. This in turn prohibits the formation of organic compounds. Instead, many scientists believe that organic compounds may have been transported to earth by the bombarding asteroids, comets, and meteorites. A zoologist by the name of David Deamer suggests that meteorites cannot carry enough organic matter to spawn life, but interplanetary dust particles that has surrounded the earth since its formation, does (Time, 1993, p.43). Another possibility would be that the large objects colliding with earth would react in a significant manner with its surroundings, possibly temporarily creating the type of atmosphere described in Miller's experiment.

Recently proposed theories involve ocean bubbles, pyrite and clay. Louis Lerman, a researcher, recently proposed that bubbles in the ocean serve as a location for life's