Abstract
The subject of evolution is one that finds substantial amount of conflict from various fronts. Much of this conflict comes from theological stance where the story of creation is consistently quoted as the viable source that defines the origin of living and non-living things. However, the creation story lacks tangible evidence as compared to the story of the evolution. There is an overwhelming body of research works and evidence that clarify this. However, despite all the evidences provided, there exists some confusion as to the origin of the earth. A quick look at various academic books used especially in primary learning shows that the story has mixed times with critics explaining that most writers and scholars are overwhelmed by the timespan under consideration (see the works of Decker, Summer and Barrow, 2007). This confusion in date estimation yields conflicting figures that make it hard to pinpoint the exact dates. However, in this essay, the learner addresses the story of evolution without necessarily delving into unnecessary commotion about which date is authentic or otherwise.
Introduction
The study of living things is a vast subject, one that entails an in depth coverage of small, medium and large living things including microscopic organisms. Each organism under consideration shows some similarities as well as some differences on various aspects. However, these similarities and differences have been brought about by various factors that influence and/ or hinder some aspects of these organisms. Over time, organisms have evolved and specialized in adaptations and growth pattern based on vital factors in their existence. Currently, six major kingdoms are used to identify organisms. To start with there are organisms classified under Archaebacteria, others under Eubacteria, others Protists, then Plants and Animals (see Holding, 2003, Hhler, 2010). Their diversity and eventual classification depends on their functionality, characteristics, and similarity of their tissues.
One of the many tasking aspects of definition of the term evolution is in the identification of where life began (Decker, Summer & Barrow, 2007). To many scientists and astronomers, it is strongly believed that the universe came into existence some 15 billion years ago or more, which is based on modern crude and limited experimentation approaches (Hhler, 2010). However, despite this notion and the underlying idea that the formation of galaxies is attributed to the combination of hydrogen, carbon, oxygen and other gases to form complex masses, clarification of the issue is still a maze that is yet to be resolved among scientists (Hhler, 2010).
According to Decker, Summer and Barrow (2007) there are various definitions that have been adopted and posited by various scholars yet two emerge to be more commonly used. The first definition of evolution is “descent with modification” while the second definition is “organic change over time” (Decker, Summer & Barrow, 2007, p. 401). Both definitions have some common aspects, which include the elements of time and life.
How did life forms evolve?
The study of evolution has found conflict, especially with the story of creation clouding the judgment of many people leading to the belief system that all life forms came into existence by a word, and that they have ever since remained in that state since inception of time. However, there is an overwhelming body of evidence that exists which negates this notion. According to Rothschild (2009), based on the last impact by a planetary mass that created an environment conducive for the existence of a living organism, it is estimated that the first living organism formed between “3.8 and 4.44 billion years ago” (p. 335). Over the succeeding billions of years, this basic, unicellular organism remained in relatively unchanged state with minimal changes being experienced (see Rothschild, 2009 and Tirichine & Bowler, 2011).
Tirichine and Bowler (2011) goes ahead to exemplify on the evolution that has taken place over time. According to Bhattacharya and Medlin (2004: Tirichine & Bowler, 2011), algae have predominantly been identified as among the first proof of evolution with their emergence as aquatic photosynthetic eukaryotes. These algae tend to vary from those that are “unicellular that are slightly over a few microns in diameter to those that have complex multicellular forms with good example being kemps that can grow up to and above 30 meters in length (Bhattacharya and Medlin, 2004: Tirichine & Bowler, 2011). The photosynthetic characteristics of algae finds its source “1.8 billion years ago when a group of unknown non-photosynthetic unicellular eukaryotes were invaded by / or engulfed photosynthetic cyanobacterium” (Bhattacharya and Medlin, 2004: Tirichine & Bowler, 2011, p. 45). The resultant effect was the formation of cells that contained photosynthetic plastids, which became surrounded by double membranes that entailed, a “highly reduced cyanobacterial derived genome” (Parker et al., 2008: Tirichine & Bowler, 2011, p. 45).
The emergent result, from this symbiogenesis or endosymbiosis, gave rise to the evolution, and diversification of these “extant Archaeplastida algae to form Glaucophyta, Chloroplastida (land plants and green algae), and Rhodaphyta (red algae)” (Simon et al., 2009: Tirichine & Bowler, 2011, p. 45). From this primary endosymbiosis, additional secondary endosymbioses led to the emergence of other photosynthetic eukaryotes that include, but not limited to, “cryptophytes, heterokonts, haptophytes and dinoflagellates” among others (Kutschera & Niklas, 2008: Tirichine & Bowler, 2011, p. 45).
What drives evolution?
Various erudite writers have posited the driving source of evolution that makes it possible for evolution to take place. However, in the works of Holding (2003) and Hhler (2010) capture the driving forces that researchers have put forth. To start with, it is claimed that most of evolutionary work takes place due to a process called positive selection (Hhler, 2010). According to this theory, when organisms are provided with options, they chose what is best for their survival. Take for example, in recent weeks prior to writing this essay, there have been strong criticism and yet clear depiction that there exists humanoid forms at sea that split from the main human activities and became mermaids, strongly supported on BBC world news under “mermaid, evidence found” and on National Geographic Channel. If these claims are true, it is then clear that a group of humans made a choice to live at sea and hunt for food and thus their structures have evolved over time.
The legendary Charles Darwin claimed that natural selection drives evolution, a posit that finds gargantuan support from most scientists (Hhler, 2010). This theory coupled with the theory of use and disuse tends to support the fact that most structural evolution is as a result of necessity to adapt in the immediate environment.
A third approach is the fact that the environment has been found to drive a species evolution drive (Hhler, 2010). Take for example, Sean Carroll, a molecular biologist from University of Wisconsin-Madison made an intriguing discovery that butterflies in East Africa had different coloration that was attributed to the time when they were hatched (Hhler, 2010). For those that were hatched during wet seasons, they had brightly colored eyespots while those hatched during dry season had neutral cryptic coats (Hhler, 2010).
Sex has also been found to drive evolution (Holding, 2003). The difference in gene expression levels has been found to occur within species although a major contributing factor is that most of the identifiable difference is attributed to sexual dimorphism, reproduction and sex-specific behavior (Holding, 2003).
Another identified argument is that self-organization drives evolution (Hhler, 2010). A good case to point out is the protein folding that tends to yield specific structures despite having billions upon billions of possibilities of structural forms, yet the science behind this theory is still raw and under consideration (Hhler, 2010).
What are the evolutionary mechanisms?
There are various factors working together to make evolution a possibility. However, despite the presence of the factors, it is also clear that the rate of evolution is relatively conservative and quite slow. There are various mechanisms that have been found to be at work in evolution. To start with, over time there have been found that alteration in genes gives rise to a new breed of organisms (Holding, 2003 and Hhler, 2010). From an analysis using biochemistry, gene alteration yields a difference in DNA structure that consequently leads to the difference in ATP synthesis (Holding, 2003 and Hhler, 2010). Gene alteration may be as a result of environmental factors. For example, it is noted that the early organisms that existed immediately after the big bang were capable of existing under extreme temperatures, which ordinary living organisms would find intolerable (Holding, 2003 and Hhler, 2010).
In some cases, an internal activity of gene mutation may happen with misalignment of ordinary DNA strands in an order that is converse to the conventional order (Holding, 2003 and Hhler, 2010). This change is later transferred to offspring leading to a permanent change in DNA structure on that lineage. Charles Darwin, a renowned scientist on the theory of natural selection posited that in as far as existence is concerned, organisms are forced by underlying circumstances to adapt to their habitat for their existence (see Holding, 2003 and Hhler, 2010). This led to the acclamation “Survival for the fittest” ~ Charles Darwin.
It is also identified that species interbreeding led to what is termed as gene flow (Holding, 2003 and Hhler, 2010). For example, a mule is an interbreed between two different species and thus the emergent species gives a different organism with different characteristics. In some cases, when the population size is large or there are some unfavorable conditions in existence, a group of the populace may decide to pull out of the main group, go to another region with different climatic conditions, and live there. The two groups, despite having similarities, will eventually have differences in their DNA composition and structure (Holding, 2003 and Hhler, 2010).
It is also claimed that under the founder’s effect, the first organism to populate a region that was previously not populated become heirs of the region and thus gradual but consistent change in genetic and physical structure is evident (Holding, 2003 and Hhler, 2010). Holding (2003) posits a rather fascinating aspect claiming that sex drive is a key contributing factor towards evolution. Holding (2003) further exemplifies on the issue stating that differences in gene expression levels tends to occur within a species while most of the differences that are identifiable are as a result of sexual dimorphism, reproduction and sex-specific behaviors. For example, it is noted that there is ample evidence that show sexual relations between ancient humans with other primitive animals.
What are the evidences of existence of evolution?
Many people have been led to believe theories based on evidence provided. First, while studying biodiversity, there are certain aspects that come into play. For example, based on the fact that living thing things have needs, it is noted that these living things have common needs, which include the need for food, water and air for them to survive (Holding, 2003 and Hhler, 2010). However, some organisms have found ways to manufacture their own food through photosynthesis. In the deep ocean exploration, it has been noted that some organisms have gone a step further to be able to produce their own light through alteration of their skin pigments and thus illuminate the ocean floor allowing photosynthetic plants and animals to manufacture their own food without the need for sunlight. This intriguing phenomena find support with the fact that there are titanic worms at the ocean floor similar to earth worms, yet their structure and adaptation is dependent on their habitat. This is one proof of existence of evolution.
Secondly, using DNA structure and ATP synthesis, it is possible to identify minute differences that exist between related organisms (Hhler, 2010). There is an overwhelming evidence as to similarities that exist between organisms which shows that these organisms shared a common ancestor (Hhler, 2010). For example, a good comparison between the genetic codes of chimpanzees and gorillas show significant similarities with those of a human depicting a common ancestor and thus the action of evolution at work (Hhler, 2010). Additionally comparative analysis show the bone structure of a gorilla and those of a human have greater similarities (Hhler, 2010).s
Through homology, it is clear that Pentadactyl lim is undoubtedly the ancestor to all vertebrates although individual organisms have modifications based on their functionalities and habitats (Hhler, 2010). Comparing the vestigial structure, in humans, the coccyx is in essence a vestigial tail, one that has diminished over time applying what Darwin called the law of use and disuse (Hhler, 2010). Fossil records give exuberant evidence from the origin of species through to bacteria, to complex cells, dinosaur and then human (Hhler, 2010).
Transitional fossils like those of Archaeopteryx show appreciable similarities with structures of dinosaurs and birds and thus the link in evolution (Hhler, 2010). From a geographic point of view, Marsupiols, which can be found in Australia, are also present in America, depicting gene drift (Hhler, 2010). Finally, the existence of antibiotic resistant strains of bacteria is a clear indication of a continuously evolving planet (Hhler, 2010). Bacteria have found a way of protecting themselves from the destructive actions of drugs like penicillin among others by modifying their membrane made possible by bacteria creating another protein coat that prevents harmful substances from entering the cell thus ensures their survival. Some organisms can remain dormant even for hundreds of years awaiting the right environment to get activated and continue their cycles.
Conclusion
In conclusion, despite evolution knowledge remaining a mystery, an overwhelming body of research and evidence supports the fact that organisms have evolved and continue to evolve although the rate of evolution is relatively conservative. Current and future research work is being focused on identification of the presence of life forms in other habitable planets by various erudite researchers and astronomers. However, despite the notions presented above, there is also looming confusion as to the exact time span that the world has been in existence. This challenge has been brought about by differences in dating and the tools in use while determining different details that make up the origin of the world. In addition, there seems to be a clear argument that evolution has happened over a long period of time and thus, although comprehending this time is vague, there is clarity that evolution takes a long time to happen.
References
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Simon, N., Cras, A. L., Foulon, E. and Lemee, R.(2009) Diversity and evolution of marine phytoplankton. C R Biol. 332, 159–170.
Tirichine, L., & Bowler, C. (2011). The plant genome: An evolutionary view on structure and function - decoding algal genomes: tracing back the history of photosynthetic life on earth, The Plant Journal, 66, 45-57. Doi: 10.1111/j.1365-313X.2011.04540.xs
