The Origin of Life
Davies opposes the assumption of scientists that life began on the earth’s surface. He has different beliefs on where life began. First, he says that it began under the surface of the earth and also views that it may have began on mars. The work on the origin of life was started by Charles Darwin. In his book “On the Origin of Species,” Darwin shows that all that is observed on the earth started long time ago from a common ancestor. However, he did not explain how life started. According to Davies, the origin of life is still a mystery. It is complex how chemicals can change to living things on their own. Therefore, this is a challenge and thus there needs a discovery of how simple chemicals transform to a complex life. The origin of life can be defined in both scientific and philosophical ways. The origin of life defines our identity. Though there are various theories, it is still in question how life began.
According to biology, on the earth, all known life is inter-related i.e. there is a genetic code that is common. This therefore shows that all organisms have a common ancestor from whom they descended. The writer speculates that there might be a likelihood of discovering a niche with a different genetic code. If discovered, it would give an implication of another descendant. In his work, Darwin compares life to a tree. Using the works of Darwin, Davies compares life to a stem, trunk or root which gives rise to branches. Therefore, one can conclude that life came from a community of microbes that were genetically interrelated.
Geologists show that the oldest fossil is in Western Australia and it’s about 3.5 billion years old. The provenance of life on earth can be traced back to a period characterized by heavy bombardment. This shows the existence of refuges where there was protection of life from bad effects and thus surviving these global bombardments.
Further, Davies writes that life began at some place on the earth. Complex ecosystems were discovered in 1977 in the depth of Pacific Ocean. Photosynthesis does not take place in darkness and thus the question of what sustained the ecosystems. This can be attributed to the presence of chemotrophs, that do not use sunlight but rather thermal and chemical energy. There have therefore been many discoveries of the existence of life under the seabed. In addition, similar discoveries have also been made on earth. For example, there have been discoveries of microbes below the ground and especially in the United States. Therefore, the fact that there is life under the earth shows that the beginning of life was in a deep subsurface setting thus it was protected from bombardment.
Davies writes that life can be divided into three, the eucarya, bacteria and archaea. Eucarya are the multicellular organisms and nuclei containing single celled organisms. Archaea are microbes which do not have nuclei. With the evidence of the existence of hyperthermophiles, we can say that life first existed in a hot and safe zone under the surface and came up after the diminishing of cosmic bombardment. According to Davies, there is evidence that life was first on the subsurface but it might as well have started on the surface and then moved to the subsurface. It is possible that some microbes which inhabited ejected rocks lived in space after cataclysm and came to the earth later. Thus we can say that the space and subsurface are a refuge from ancient bombardment. Microbes can survive in extreme conditions. For instance, they can withstand accelerations and heat that propels a rock into orbit and also cold conditions like freezing which preserves bacteria.
There is evidence that there was transfer of organisms from ecosystems on mars and the earth. This then shows that there are no biological isolations between the earth and mars and that in history, there has been a cross-contamination between these two planets. However, there is the question whether mars rocks can pass on microbes to the earth. Though there are 15 meteorites identified to have a Martian origin on earth, there are still doubts about this. However, though there are doubts, it gives a possibility of life existing in mars and maybe the possibility of microbes on earth that came in rocks that were ejected from mars. There is a higher probability that rocks come to the earth from mars since mars has a smaller gravity thus easier escape of materials. Thus if organisms in mars have a resemblance with terrestrial microbes, there are chances that some reached the earth alive. This then raises the possibility of life having begun in mars.
In the early times, mars was more favorable for the existence of microbes. This is because of its small size which allows quick cooling and thus refuge from ancient bombardment. In addition, mars was favorable since it suffered a lower violence degree during impacts. Since mars has a low surface gravity, the escape of microbes to space for refuge was easier since there was less violence during ejection into the solar orbit. Thus mars was frequently recolonised since the conditions repeatedly improved and thus microbes returned. Whether life thrived in mars for long or not, there is evidence that it existed.
This can however be challenged since today, a microbe can not survive the ultra-violet radiation and thus can not survive the number of years required for it to get to another planet. Though there are some scientific facts for example the existence and survival of bacteria in freezing conditions, most of Davies work is based on theory. It is true that the known living organisms are related. This then supports Davies work that life originated from a common ancestor. The living organisms are interrelated in both genetic and chemical composition. Because of the existence of life on the earth and mars in the ancient times, it shows that both planets have common feature that support life. However, the theory of life originating from mars and then coming to the earth can be challenged. If it were so, placing heavy impact on the earth’s rocks for them to return to mars would imply that some microbes would go with them and survive in mars. Therefore, though the known living organisms came from a common ancestor, there is no setting that is precise on where life originated from.
References
Davies, P. The origin of life: When and where did it begin? Retrieved from: http://cosmos.asu.edu/publications/papers/OriginsOfLife_I.pdf. Accessed February 2, 2011.
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