Four Most Important Turning Points in the History of Life - Essay Example

Insert name Instructors’ name Course Date History History is among the most defining moments in life today. History revolves around the central ideas of evolution which changes over time. In light of these sentiments, there are different species sharing the same common ancestor. The evolutionary history of life traces back to the Yester years whereby fossils and other organisms evolved since the origin of the planet to the present day. Tentative research indicates that the earth began 4.5 billion years ago, and life has been on its surface ever since the first billion years. It is apparent that the present day organisms present a quantifiable difference to the past organisms which can be explained through divergent evolution. For instance, the microbial mats, which include bacteria and archaea, were predominantly coexistent in the early Archen family and have evolved significantly ever since (Christian, 45). In addition, research opines that, the earliest land marks dates back to over 450 million years ago. It is hence apparent that the land plants contributed immensely to the late Devonian extinction event that happened way back history lane. It is also evident that, in the Yester years, the earth was more geographically violent as it suffered prevalent bombardments from meteorites. Once this was over, the Earth cooled after which the surface solidified to form crust. As at yet, no continents were visible continents formation only some peppered with some small islands. Factors like erosion, volcanic activity and sedimentation profoundly impacted the meteor impacts and eventually led to the creation of pro continents. However, this activity proceeded up until the current continent size was formed approximately 2.5 million years ago. The earth maps have diverged from the initial formation as they have collided and been torn apart given the prevalent activities that have let to this transformation. It is notable that the history of life revolves around a single cell prokaryotic cell for instance bacteria. The multi-cellular organisms evolved years later, and such organisms initially to be formed where the arthropods, and the fish followed. However, the land plants as well as the forests and mammals delayed in evolving until 200 million years ago than the Homo sapiens followed. It is hence apparent that the Homo sapiens have been part of the earth’s history for a mere 0.04 percent. The intention of this discussion is to delineate the four most vital elements in the history of life. The oxygen evolution The oxygen evolution was commonly known as the dominant oxidation event also known as the oxygen catastrophe or oxygen crisis. The main idea behind this catastrophe was the idea that, biologically, there was free oxygen induced in the atmosphere. According to geological, chemical, as well as isotopic evidence through tentative research, sweeping environmental changes took place around 2.4 billion years ago. Before the oxidation crisis ever happened, cyanobacteria began producing free oxygen. 200 million years before the dominant oxidation event, oxygen was introduced in the environment through photosynthesis. Additionally, before the oxidation event, oxygen was released chemically into the environment through dissolved iron or organic matter. The complete oxidation event took place when oxygen sunk and became saturated in the atmosphere as the oxygen produces through cyanobacterial photosynthesis no longer be captured. After the great oxidation, free oxygen continually accumulated in the atmosphere. It is notable that, the accumulated free oxygen is substantially harmful to the anaerobic organisms. As such, the gradual rising concentrations could eventually deplete the anaerobic inhabitants. Through the information relayed through this tentative research, the Cyanobacteria resonated to a considerable extinction event revolving around the history of life. Additionally, the free oxygen reacted with numerous gases for instance methane, as well as a greenhouse gas (Schopf, 57). This in itself led to the triggering of Huronian glaciations, which was among the longest snowball episodes on earth. Ever since that historical event, oxygen has been a fundamental aspect in the world’s atmosphere. Over the years, numerous research assertions have been relayed trying to explain the sole reason that facilitated the massive oxidation. Among them is the notion that, free oxygen was first introduced into the environment by prokaryotic organisms and later enforced by the eukaryotic organisms. The scholars spearheading this argument relied on the theory that, these organisms carried out photosynthesis which resonated to oxygen as a free product. However, these organisms were existent 3500 million years before the occurrence of the positive oxidation event. Other scholars bearing a different opinion criticize this assertion the basis that, the weathering of reduced minerals for instance iron would majorly reduce the free oxygen levels. In addition, prevalence of free oxygen was predominant 50 years to the inculcation of the oxidation event. Since there was no mechanism to negate the free oxygen accumulation, the gradual rate increased and is prevalent up to date. Currently, the rate of photosynthesis is greater than the yester years implying that the current or modern atmospheric oxygen levels are quite high. Whichever the case, free oxygen accumulated in the atmosphere and resonated to notable impacts. As a result, there two outstanding notable impacts; first, atmospheric methane was iodized to form carbonic dioxide, which is a weaker gas and eventually led to Huronian glaciations. This was the longest snow ball episode as it lasted a record 400 million years hence implying that this was a full blown effect. The second considerable impact emanating from free oxygen in the atmosphere was that, the increase in oxygen diversification facilitated biological diversification and this led to changes in the prevalent chemical interactions between clay, sand, rocks and other geographical substrates. This implies that, before the limitless availability of oxygen, life was somewhat limited despite the prevalent recycling of organic matter. It is undoubtedly evident that, after the proper oxidation event, metabolic evolution took place and led to a major increase of free energy to the living organisms. Appearance of Eukaryotic organisms The Eukaryotes are commonly known as the Eukarya or the Eukaryota or the kingdom of life. In this light, their initial formation was a tremendous event and is among the notable histories of life. In addition, the origin of the Eukaryotes dictates the lives of the higher plants as well as animals. The Eukaryotes in itself contain complex cellular structures enclosed within membranes. The origin of the Eukaryotes is a key milestone in the history and evolution of life. This is because; the cells are complex and most of all support most multi cellular organisms. However, with the passage of time of time, the estimation of the occurrence of these events is at time hard to determine. According to some scholars, the evolution took place 1.6 to 2.3 billion years ago. Some species such as the acritarchs date to 1650 years into the past. On the other hand, the alga Grypania existed approximately 2100 years ago. Other species including the black shale date back 2.1 million years ago. Eukaryotic life profoundly has evolved during that time and affected the history of life to what is prevalent in the modern day. Biologists, as well as other technocrats in the field of academia, believe that the Eukaryotes is a complex cell, and it resonated to the prokaryotic counterparts. There is substantial evidence that purports to indicate that evolution steps have played a key role in ensuring that the cells gradually separate. It is clear that the Eukaryotes evolution dates way back time immemorial when the atmosphere had little or no oxygen. This was maybe two billion years ago, and as per the current research analysis, the Eukaryotes evolution is in flux and continuous. As far as the history of life is concerned, the Eukaryotes play a fundamental role as pertain higher level plants and animals for instance the human beings. As per the ordinate facts prevalent as purported by modern biologists, Eukaryotes are an ancient evolutionary milestone as far as the history of life is a concern. The only hindrance is that there is no research institution or personality who explains with certainty of the evolutionary dynamics underlying the formation of the Eukaryotes (McAlester, 79). Sexual reproduction It is notable that every aspect of evolution of life is described by a number of hypotheses each with competing facts. The evolutionary sexual reproduction is no exception. The first theory fronted by scholars from the field of academia with regard to the sexual reproduction opines that the Eukaryotic species is the common ancestor of sexual reproduction. Many of the multi cellular organisms including plants, animals, fungi, as well as the protists, reproduce sexually. There are two distinct themes that revolve around the evolution of sex. These themes revolve around the origin and maintenance. In addition, since the evolution of sex is difficult in terms of testing, most of the work has not been focused on its origin but its maintenance. It is noteworthy that the sexual cycle improves the quality of fitness or the progeny. However, this eventually reduces the number of the offspring derived. For sexual evolution to contain admirable advantage there, has to be a notable increase in the overall fitness of the offspring. Among the most indicated advantages, the creation of an offspring bearing generic variation is an acceptable explanation. There also lays another advantage emanating from molecular advantage of the offspring commonly referred to as hybrid vigor or heterosis also known as the masking of mutation. The advantage that emanates from genetic variation has been explained on a diversified platform. The origin of sexual reproduction dates back 1200 million years ago. The ancestor of the sexually active organisms is the Eukaryotic single celled species. Many of the multi-cellular organisms produce sexually. However, over the years, a few species have lost this feature given the passage of time. The fundamental principle that underpins this assertion is the fact that, organisms have the desire to replicate in a reliable and efficient manner. Evidence both research and scholarly indicate that, sexual reproduction emerges from Eukaryotic evolution hence the prevalence of the meiosis features in the Eukaryotes. There are various theories forwarded that seek to explain the entire origin of sexual reproduction (Fastovsky and Weishampel, 55). Asteroid impact of the late Cretaceous period causing the extinction of dinosaurs and for mammals to appear The extinction event of the Cretaceous Paleocene took place almost 66 million years into the past. This bore a mass extinction campaign that attributed for over 75 percent of the extinctions revolving around animals and plants. Also known as the Cretaceous tertiary extinction, this evolutionary aspect of history of life bears a significant blunt as it dictates the modern way of life. This is among the four corner stone’s of evolution controlling life. This is because; first, a wide range of species perished entirely in the light of the K – Pg extinction. For instance, the non avian dinosaurs are among the untimely victims. It is also notable that this endeavor affected a number of terrestrial organisms. They include; mammals, birds, pterosaurs, insects, lizards, as well as plants. It is hence evident that in this revolutionary phase of the history of life, over 75 percent of all Earth’s species vanished. In the wake of this extremely memorable evolution phase, many groups of underwent extensive adaptive radiations. The most memorable phase is that fact that he mammals underwent diversification focusing on the Paleogene, and the results were evident. This is because, out of this elaborate process, new formation of horses, bats, whales as well as primates were evident. Additionally, birds, lizards and fish also radiated (Vermeij, 34). Conclusion In conclusion, It is apparent that history plays a focal point in our lives today. This is because; history defines where life emanated from and how things fell into the current state of affairs. The history of life has four pivotal points that suggest that life emanated from unicellular organisms. According to this theory, there four pivotal points were; the great oxidation, the appearance of Eukaryotic organisms, the sexual reproduction and the asteroid impact of the late Cretaceous period causing the extinction of dinosaurs and for mammals to appear. These four theories fundamentally lay a basis to the history of life and scholars need to articulate them in a more basic manner to enhance adequate flow of information. Work cited Top of Form Christian, David. Maps of Time: An Introduction to Big History. Berkeley: University of California Press, 2004. Internet resource. Fastovsky, David E, and David B. Weishampel. The Evolution and Extinction of the Dinosaurs. Cambridge: Cambridge University Press, 2005. Print. McAlester, A L. The History of Life. Englewood Cliffs, N.J: Prentice-Hall, 2007. Print. Schopf, J W. Major Events in the History of Life. Boston: Jones and Bartlett, 2002. Print. Vermeij, Geerat J. Evolution and Escalation: An Ecological History Oflife. Princeton: Princeton Univ Press, 2003. Print. Bottom of Form Read More