The Earliest Evidence of Life on Earth - Essay Example

hе Еаrliеst Еvidеnсе Fоr Lifе on Earth Name Course title Date The earliest evidence for life on Earth can be traced through evolution processes of living and fossil organisms, for the period that the earth has been known to exist. Scientists claim that the Earth has been in existence for approximately 4.5 billion years, with life appearing on earth in its initial 1 billion years (Schopf, 1995). Researchers have identified similarities in all living organism that they existed from a common ancestor but have grown to different species through the evolution process. Different theories exist explaining the earliest existence of life on earth. Furthermore, different studies conducted in different periods have shown varying results on the analysis of life existence on the planet earth. However, most of them have concluded that all living organisms have undergone through a process of evolution to their current state (Hublin, 2001). This paper reviews the earliest evidence for life on Earth, the evidence form they take as well as the locations of existence. Moreover, it discusses the controversies relating to some of the evidence on earliest presence of life on Earth. Studies of existence of early life can be explained by the Archaean cellular life theories. Records on rocks provide some unique information on the existence of cellular life in. However, the biogenetics results of stromatolites and ‘microfossils that are older than 3 billion years old requires critical analysis foe the accurate information to be obtained. The morphospace as well as context of life existence requires studies and analysis using the recent methods and techniques when devising hypothesis and making conclusions (Tillier and Hublin, 1999). This has been concluded being not satisfactory based on the biogenicity presumptive indicators concerning ancient morphology and carbonaceous chemistry. Moreover, Martian microfossils theories utilize carbonaceous cherts such as Apex Chert to explain their finding on life existence. The massive presence of isotopic carbonaceous cherts that are light provides signals that are hard to ignore on early presence of life. Strelley Pool Chert maps sandstone grains that have been preserved well for the last 3.4 billion years. Therefore, using geochemical processes these sand grains consist of endolithic microtubes that show syngenicity and origin of microbial in the early studies as Stringer, Dean, and Martin (1990) state. Although the existing Archaean rocks located in Greenland and Labrador have undergone metamorphosis to conduct early life existence and adds complexity to the matter, existence of well-preserved rocks from Western Australia, South Africa regions and Swaziland shows signs of life. Hydrothermal and volcanic processes on the granite, barite, alunite and jarosite stones found on the floor of the sea show that there existed cracks on these stones that could have been made by living organisms given that there was minimal carbonic processes (Knoll, Javaux, Hewitt and Cohen, 2006). In proving the existence of cellular life in these Archaean theories have utilised more of biological explanations than geochemical evidences on metabolic cycle. The statistics show that there is a high precision of a rare earth element such as dolomite in the marine life origin (Scott and Turner, 1997). Therefore, deeper analysis of the biotic and abiotic organisms in these rocks provides evidence of existence of putative microfossils separating them from host rocks. On the other hand, controversies surrounding the early existence of cellular life have helped in development of astrobiology strategies and improved criteria for testing Archaean life claims. Furthermore, these debates provide sufficient information to handle future debates on existence of life that may emerge in the science community. Hence, they help refine the information that will be used by scientists in testing the samples that will be obtained from other planets like Mars or Venus, if successful mission are achieved (Dean, 1995). Furthermore, genetic material studies have revealed that Archaea which are single-celled organisms living in groups were the initial living organisms on the surface of the Earth. Currently these living organisms inhabit saline water, hot springs, deep-sea vents as well as harsh marine environments. However, controversy occurs in concluding fully that modern Archaea were initial living organisms because of the complexity introduced by existence of inorganic structures as well as simple biological structures. This evidence of early life existence can be dated approximately 3.5 billion years old when discovery of sedimentary structures in Western Australia were discovered (Brasier, Green, and Mcloughlin, 2004). The sedimentary structures resembled stromatolites. Currently, these stromatolites can be found in Belize and Bahamas. Analysing these Archean structures it has been found out that layers that are similar to those found in the existing stromatolites are evident in the early structures. Likewise, scientists have identified simple filamentous microfossils from these layers. Some scientists have stated that these living organisms could have been formed through inorganic processes. However, existence of sedimentary structures that are formed by living organisms points to existence of living organisms in additional to organic processes involved in their development. Therefore, scientists have concluded that evidence on early life existence can be traced back to existence of these ancient microorganisms from the sea (Futuyma, 2005). In addition, Charles Darwin is among the significant contributors to the history of early life existence on earth. Darwin’s studies that have been accepted by several scientists show that during the Precambrian period that explains almost three quarters of earth’s history, there was life existence on earth’s surface. However, controversy exists in his theories since he alleged that in Phanerozoic strata, that were used to analyse life existence in younger rocks, could be used in Precambrian but it was hard to establish proof. During Precambrian, it was hard to analyse the surface of the rocks to obtain candid information to conclude existence of life in the early times without the use of microscopes because early living organisms were minute and invisible. The use of powerful microscopes to identify Precambrian fossils by scanning the availability of fossils in samples of rocks obtained is a reliable strategy because the high resolution obtained separates clearly the microorganisms from the rocks giving reliable results (Altermann and Kazmierczak, 2003). They test existence of Acritarchs, Cyanobacteria and Stromatolites fossils in the rocks to prove the earliest existence of life on the surface. The findings shows some of the earliest form of life are fossils are cyanobacterium-like microbes that are complex living organisms. However, identifying the exact time when these living organisms existed has been impossible with approximations being made that they existed on Earth about 3.9 billion years ago. History shows that in the earlier years powerful incoming meteorites that could have killed the existing living organisms because of high temperatures emitted invaded the Earth. In addition, more questions continue to haunt the paleobiologists and scientists for sufficient proof of this early life existence on Earth’s surface (Futuyma, 2005). On the other hand, discrepancies and controversies do not emerge on whether live existed on earth or not but on the condition in which life could have existed. This is due to researches on rocks shows that life existed before formation of these rocks. Geologists state that after the bombardment period the existing rocks shows traces of graphite that is a carbon matter that only exists due to decomposition of organic matter. These rocks were obtained from the seafloor where most of surface deposits are located in large amounts after rains pour and erosion occurs. Studies claim that earlier rocks past 3.2 billion years could not provide tangible evidence on life existence since these rocks have undergone weathering due to heat, deformation and pressure. Therefore, rocks younger than that period provide useful information that helps chemical record predict in an accurate manner on how life changes the surrounding environment using chemistry principles. The chemical recorded used in determining evidence of ancient life is found in chemofossils that relate carbon isotopic ratio that is useful in these researches. Given that carbon exist in more than one form, carbon-13 is difficult to find than carbon-12. Nevertheless, accumulation of carbon-12 is made possible by biological processes and when the organic rock debris is swept into the sea, the ration of C-12 increases than C-13 (Knoll, Javaux, Hewitt and Cohen, 2006). The ration concentration is preserved for many years and this helps research to obtain significant information relation to ancient life existence. Therefore, through chemical processes it is able to identify that high ratio of C-12 to C-13 can only be obtained by existence of living organisms. Akilia Island and Greenland were a source of those rocks that were found to contain such characteristics. Many geologists have concurred with these findings that high ration of C-12 to C-13 can only be realized where there is high organic activity. Since it is hard to conclude that the carbon in these sedimentary rocks is about 3.5 billion years, identifying some crystals found in them called zircons helps to determine the minimum age of these rocks that leads to identifying the minimum age of the rocks. This is due to fact that crystals forms after the rocks have been formed. Although controversy surrounds identifying the exact age for these rocks, the availability of samples helps to experiment them rather than depending on speculation and theory. Obtaining better result on the obtained samples from the earth would lead to successful experiments on approximation of life in other planets in the future (Hayes and Waldbauer, 2006). In conclusion, it can be noted that these theories and experiments for the existence of earliest life on Earth can be identified be around 3.5 billion years ago. The Archaean cellular life theories, genetic material studies, Darwin fossil theories and experiments in additional to chemical processes all lead to concluding that life really existed in the ancient times. We cannot confidently state the exact date of life existence on Earth but we can estimate the duration of life existence on Earth’s surface. These findings will help scientist in prediction of life in other planets. Therefore, these finding are important to on-going discussions of life existence in Mars and other planets more than knowing the exactness of life existence in ancient times. Reference List Altermann, W. and Kazmierczak, J. 2003 “Archaean microfossils: a reappraisal of early life on Earth”. Res Microbioliology, 154: 611–617. Brasier, M. D., Green, O. R. and Mcloughlin, N. 2004 “Characterization and critical testing of potential microfossils from the early Earth: the Apex ‘microfossil debate’ and its lessons for Mars sample return”. International Journal of Astrobiology, 3: 1–12. Dean, M.C. 1995 “Aspects of Dental Biology: Palaeontology, Anthropology, and Evolution”, International Institute Study Man, pp 239–265. Futuyma, D. J. 2005. Evolution. Sunderland, Massachusetts: Sinuer Associates, Inc. ISBN 0-87893-187-2. Hayes, J. M. and Waldbauer, J. R. 2006 “The carbon cycle and associated redox processes through time”. Philosophy Translation Sociology Journal, 361: 931–950. Hublin, J.J., 2001 Human Roots, Bristol, UK: Western Academic and Specialist, pp 99–121. Knoll, A. H., Javaux, E.J, Hewitt, D. and Cohen, P. 2006. "Eukaryotic organisms in Proterozoic oceans". Philosophical Transactions of the Royal Society B 361 (1470): 1023–38. doi:10.1098/rstb.2006.1843. Schopf, J. W. 1995. Evolution and the Molecular Revolution, Boston: Jones and Bartlett Publishers, pp. 87-1 15. Scott G.R. and Turner C.G. 1997 The Anthropology of Modern Human Teeth, Cambridge, UK: Cambridge University Press. Stringer, C.B., Dean, M.C., and Martin, R.D. 1990. Primate Life History and Evolution, New York: Wiley–Liss, pp. 115–152. Tillier, A.M. and Hublin J. J., 1999. Aspects of Human Evolution, London Taylor and Francis, pp 167–185. Read More

Hydrothermal and volcanic processes on the granite, barite, alunite and jarosite stones found on the floor of the sea show that there existed cracks on these stones that could have been made by living organisms given that there was minimal carbonic processes (Knoll, Javaux, Hewitt and Cohen, 2006). In proving the existence of cellular life in these Archaean theories have utilised more of biological explanations than geochemical evidences on metabolic cycle. The statistics show that there is a high precision of a rare earth element such as dolomite in the marine life origin (Scott and Turner, 1997).

Therefore, deeper analysis of the biotic and abiotic organisms in these rocks provides evidence of existence of putative microfossils separating them from host rocks. On the other hand, controversies surrounding the early existence of cellular life have helped in development of astrobiology strategies and improved criteria for testing Archaean life claims. Furthermore, these debates provide sufficient information to handle future debates on existence of life that may emerge in the science community.

Hence, they help refine the information that will be used by scientists in testing the samples that will be obtained from other planets like Mars or Venus, if successful mission are achieved (Dean, 1995). Furthermore, genetic material studies have revealed that Archaea which are single-celled organisms living in groups were the initial living organisms on the surface of the Earth. Currently these living organisms inhabit saline water, hot springs, deep-sea vents as well as harsh marine environments.

However, controversy occurs in concluding fully that modern Archaea were initial living organisms because of the complexity introduced by existence of inorganic structures as well as simple biological structures. This evidence of early life existence can be dated approximately 3.5 billion years old when discovery of sedimentary structures in Western Australia were discovered (Brasier, Green, and Mcloughlin, 2004). The sedimentary structures resembled stromatolites. Currently, these stromatolites can be found in Belize and Bahamas.

Analysing these Archean structures it has been found out that layers that are similar to those found in the existing stromatolites are evident in the early structures. Likewise, scientists have identified simple filamentous microfossils from these layers. Some scientists have stated that these living organisms could have been formed through inorganic processes. However, existence of sedimentary structures that are formed by living organisms points to existence of living organisms in additional to organic processes involved in their development.

Therefore, scientists have concluded that evidence on early life existence can be traced back to existence of these ancient microorganisms from the sea (Futuyma, 2005). In addition, Charles Darwin is among the significant contributors to the history of early life existence on earth. Darwin’s studies that have been accepted by several scientists show that during the Precambrian period that explains almost three quarters of earth’s history, there was life existence on earth’s surface.

However, controversy exists in his theories since he alleged that in Phanerozoic strata, that were used to analyse life existence in younger rocks, could be used in Precambrian but it was hard to establish proof. During Precambrian, it was hard to analyse the surface of the rocks to obtain candid information to conclude existence of life in the early times without the use of microscopes because early living organisms were minute and invisible. The use of powerful microscopes to identify Precambrian fossils by scanning the availability of fossils in samples of rocks obtained is a reliable strategy because the high resolution obtained separates clearly the microorganisms from the rocks giving reliable results (Altermann and Kazmierczak, 2003).

They test existence of Acritarchs, Cyanobacteria and Stromatolites fossils in the rocks to prove the earliest existence of life on the surface.

Read More