Cambrian Explosion Theory Explanation - Research Paper Example

Cambrian exposition Affiliation Cambrian Exposition Cambrian exposition is one of the Darwin’s theories that attempted to explain the origin of life. Cambrian exposition refers to the geological sudden emergence of multi-cellular living organisms in the fossil records in the Cambrian period. During the Cambrian exposition, about forty-one different phyla appeared on the earth. Phyla are composed of the highest biological categories in the kingdom of animals. Each Phylum has distinctive characteristics that it exhibits. Some of these traits include unique structural body plan, blueprint, and unique architecture. Some of the animals with basic animal bodies include arthropods such as insects, crustaceans, and trio-bites, cnidarians like jellyfish and corals, mollusks such as shellfish and squids, echinoderms like sea urchins and sea star, and chordates such as vertebrates. The Cambrian exposition occurred during the Cambrian period that began 570 million years ago and ended 510 million years. According to Meyer et al. (2001), the Cambrian exposition occurred within a window of 20 to 40 million years during the Cambrian period. According to BBC, (2015), the Cambrian period began 545 million years ago and ended 495 million years ago. The Cambrian period was characterized by the sudden emergence of living organisms in the sea. Although geologists are lucky to identify some Cambrian fossils, there was no life on the land. According to Darwin’s theory, the Cambrian exposition is based on the existence of changing environmental conditions that cause genetic modification of genes. The major cause of the Cambrian exposition is believed to be a rapid increase in the oxygen level in the atmosphere. An increase in oxygen level in the atmosphere occurred approximately 2.3 or 3 million years when numerous microorganisms released oxygen to the atmosphere through photosynthesis. The second oxygen increase event occurred approximately one billion years ago and resulted in the development of various complex organisms during the Cambrian period. The link between the increase in oxygen levels and development of complex organisms is confirmed by various past events. For instance, the oxygen concentration is believed to have increased from 10 % to 21% in the past 425 million years. The event resulted in the evolution of vertebrates thus attaining essential features. Secondly, high oxygen concentration level in the atmosphere resulted in an increase in insect size (Koch & Britton, 2009). According to Penumaka (2011), the earth was covered by glacier 580 million years ago thus limiting the increase in oxygen. However, the glacier melted before the occurrence of the Cambrian period, and plenty of nutrients were released into the seawater. Availability of the nutrient content in the sea enabled resulted in proliferation of small organisms such as phytoplankton thus releasing oxygen to the atmosphere. In addition, Ediacaran biota, soft-bodied fossils, and complex organisms increased and developed during the glacier meltdown thus confirming that the emergence of complex organisms is closely associated with oxygenation event. Although the increase in oxygen level is associated with the emergence of living and complex animals, the amount of oxygen required or used by primitive organisms is unpredictable. The occurrence of the Cambrian exposition was contributed by multiple causes as identified by Ghose (2013). The rise of oceanic sea level is one of the key factors that contributed to the emergence of living animals on the earth during the Cambrian exposition. The rise of the sea level during the Cambrian exposition resulted in flooding in the low and flat areas. The area flooded by the sea water provided more and vast habitats for organisms and supported life. In addition, floods that occurred in rocks and minerals results in an infusion of minerals such as strontium and calcium into the sea. Infusion of some minerals activated some protein components in the sea thus giving rise to living organisms. Thirdly, genetic changes in the homeotic genes contributed to the occurrence of Cambrian exposition that resulted in the emergence of different living organisms during the Cambrian period. Homeotic genes are unique genes that are responsible for segmentation of basic set of genes thus producing a wide range of unique species. According to Penumaka (2011), all the phyla formed during the Cambrian exposition were composed of homeotic genes that varied between four individual genes to thirteen genes. Homeotic genes were mainly found animals, and they may have caused a diversity of organisms through duplication of genes and genetic changes. Cambrian exposition may have been caused by withering of rocks as stated by Sakai (2012). The presence of the Great Unconformity reveals that the Cambrian exposition may have been geologically triggered. The Great Unconformity is a flat-lying sedimentary rock of approximately 525 million years. Shaman Peters, a geoscience professor, University of Wisconsin-Madison suggested that the missing rock records may hold some information on what happened during the Cambrian exposition. According to Peters, withering of rocks resulted in biomineralization evolution caused by increased influx of withered materials in the sea during the Cambrian period. Deposition of withered materials in the sea affected the sea water chemistry where the water contained high rates of carbonate minerals. According to the fossils record, three major biominerals are contained in living animals such as vertebrates and invertebrates’ organisms. For instance, bones and teeth are made up of calcium phosphate that is believed to have been deposited in the sea water during the Cambrian period. Secondly, invertebrates’ shells contain large amounts of calcium carbonate. The mineral calcium carbonate is found in rocks that are likely to have been eroded and deposited in the sea water during or before the Cambrian exposition. Lastly, silicon dioxide is among the minerals that are closely associated with a diverse array of organisms. Silicon dioxide exists in radiolarians thus related to diversification and formation of organisms during Cambrian exposition (Sakai, 2012). Tectonic shifts are also major causes of occurrence of Cambrian exposition. Tectonic shifts are movements of the tectonic plates beneath the earth’s surface over other plates. Tectonic shifts contributed to the occurrence of the Cambrian exposition through raising the sea level. Movement of the tectonic plates resulted in a rise in the sea level in most of the places. Consequently, the rise in sea water level resulted in flooding of lowlands and erosion of mineral materials on the land. Erosion of rock and mineral materials changes the water chemistry thus triggering the Cambrian exposition. In addition, floods on lowland provided good habitats where organisms would survive. Although most of the facts of the occurrence of the Cambrian exposition are accepted by many scientists and geologists, some of them are strongly opposed to various bases. For instance, Astrobio (2013) reveals that oxygen was not a cause of the Cambrian exposition. Although different researchers, scientists, and geologists agree with the theory that the increase in oxygen concentration triggered the occurrence of Cambrian exposition, Professor Canfield and his team disagreed with the theory. According to their research findings, the oxygen concentration level in the atmosphere 2.1 billion years ago was most likely the same as during the Cambrian exposition. The research group revealed that there was plenty of oxygen concentration even before the occurrence of the Cambrian explosion. After the researchers had examined rocks that are 2.15 billion to 2.08 billion years old, they found out that there was oxygen in deep waters thus revealing that oxygen was also present in the atmosphere. According to them, presences of oxygen did not have a significant impact on the occurrence of the Cambrian exposition. In addition, the research group led by Canfield stated that microbes would not evolve into multicellular organisms. Therefore, their statement and findings were against the Darwin’s theory. According to Astrobio (2013), the research group also revealed that the atmosphere had a lot of oxygen about 2 billion years ago that contributes to the development of new understanding regarding the development of the earth. According to their research, the level of oxygen concentration experienced variations from time to time. For instance, 250 to 300 million years ago the concentration of oxygen in the air increased to about 25 percent. The increase in oxygen concentration resulted in emergence or appearance of some enormous insects on the earth. In addition, the high level of oxygen in the atmosphere increased the risk of igniting trees. Therefore, they concluded that there were instances of wildfires due to increased oxygen levels as revealed by ash layers examined. In conclusion, the occurrence of the Cambrian exposition was caused by geological factors, biological factors, and geochemical factors. Geological factors that were likely to cause or trigger the Cambrian exposition include glacier meltdown, tectonic shifts, weathering and erosion of mineral rocks. Biological factors mainly include genetic evolution and genetic changes of simple organisms to complex and multicellular organisms. Lastly, geochemical factors that contributed to the occurrence of the Cambrian exposition include deposition of chemical based materials and increase in oxygen level. References Koch L & Britton S. (2009). Aerobic metabolism underlies complexity and capacity. American Journal of Respiratory Cell and Molecular Biology 40: 507Z510. Smith P & Harper D.(2013). Causes of the Cambrian Explosion. Science 20 September 2013: Vol. 341 no. 6152 pp. 1355-1356 DOI: 10.1126/science.1239450 Ghose T. (2013). Evolutionary Big Bang Was Triggered by Multiple Events. LiveScience. Retrieved from http://www.livescience.com/39790-cambrian-explosion-had-multiple-causes.html Sakai J.(2012). Evidence for a geologic trigger of the Cambrian explosion. News. Retrieved from http://www.news.wisc.edu/20576 Astrobio (2013). Oxygen Not the Cause of the Cambrian Explosion. ASTROBIOLOGY MAGAZINE. Retrieved from http://www.astrobio.net/topic/origins/origin-and-evolution-of-life/oxygen-not-the-cause-of-the-cambrian-explosion/ Penumaka A.(2011). The Cambrian Explosion and the Origins of Diversity. Harvard Science Review. Fall. Retrieved from http://www.hcs.harvard.edu/~hsr/wp-content/uploads/2011/11/The%20Cambrian%20Explosion%20and%20the%20Origins%20of%20Diversity%20-%20Anirudh%20Penumaka.pdf Meyer S, Nelson P & Chien P. (2001). The Cambrian Explosion: Biology’s Big Bang. Retrieved from http://www.discovery.org/articleFiles/PDFs/Cambrian.pdf Read More