Example Biology Essay

Example Biology Essay
In general, the term 'evolution' can imply a drastic orgradual change from a very broad perspective. Life on earth, the universe,galaxies, as also the earth in general have evolved through millions of years.In this essay we consider only one aspect of evolution emphasizing on evolutionas a biological tool for change among species and consider fossil record assupportive of both evolution theories and also the other theories contrary toevolution. Evolution is the central unifying concept, a theory thatsuccessfully connects biology, paleontology and other branches of science.Evolution is a gradual descent of organisms accompanied by changes that helpthe organisms to adjust and adapt to the surroundings. 'Descent withmodifications' as Darwin contended implies changes in organisms in successivegenerations (Mayr, 1976). These changes are triggered by the derivation of newspecies and there is a change in the properties of populations of organisms andthese properties tend to transcend the lifetime of any single individual. Newerspecies are modified versions of older species.
Although, individual organisms do not biologically evolve,populations evolve when heritable genetic materials are transmitted from onegeneration to another. Biological evolution can range from very limited changesto drastic transformations on a large scale changing the entire speciesaltogether and bringing in new forms. Evolution can thus be defined asinheritable changes in populations of species that are spread and transmittedover many generations (Zimmer, 2002). It is also more scientifically defined aschanges in the frequency of alleles within a gene pool carried throughdifferent generations as understood in the Darwinian version of the theory(Dawkins, 1989). Evolution studies are supported by detecting changes in genefrequency within a population and the fact that the theory of evolutionemphasizes on a common ancestor, only indicates that two or more species showsuccessive heritable changes in populations since they are separated from eachother as distinct forms (Allen and Briggs, 1989). Most popular definitions ofevolution however highlight not the transmission of heritable traits andchanges but the processes of diversity that has given rise to millions ofspecies from the most primitive organisms. Here however we move on to theevidence for and against evolution theories and the role of fossil record inthis context. Some researchers claim that the theory of evolution has beensupported by four primary sources that serve as evidence (Zimmer, 2002; Allenand Briggs, 1989):

1. The fossil record that tracks changes in early andprimitive forms of life

2. The anatomical and chemical similarities in theconstitutions of different species.

3. The genetic changes observed and recorded in severalliving organisms over several generations

4. The geographical spread and distribution of species thatseems to suggest a definite pattern, and

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