Wednesday, 5 September 2012


Dasuni Tennakoon

At some point, you may have come across Adam and Eve; the story of the first two humans to walk the planet. Whilst this is a popular and controversial story, the story of how humans arrived on earth is arguably a more interesting story. Humans and all other organisms are said to be present on this earth due to a process called evolution.  ‘Evolution is the change in properties of organisms that transcend the lifetime of a single individual, which results in heritable changes in a population over many    generations (Moran, Laurence 1993).’ This process can explain the existence and extinction of many of the species present today. 

Text Box: Evolution-Coyle, Daniel 2012 
The mechanism of evolution is a complicated one, with many aspects involved, namely mutations, adaptations and natural selection, and genetic drift. Mutations are altered sequence of nucleotide base pairs in DNA which codes different genes. Depending on the instance, these mutations may be advantageous or disadvantageous for the species (Moran, Laurence 1993). Darwin’s Theory of Natural Selection is an unguided process where traits that increase an organism’s survival chance is passed down generation while others are ‘weeded out’. (Wolf, Lone 2012). This is due to adaptations (characteristic that has developed to advantage the organism) by the organisms to its surroundings. Genetic drift occurs when two identical populations differentiate due to living in separate environments. The final mechanism is speciation, where by two populations gain genetic differences due to selection pressures which causes two entirely different species to form. Consequently, these mechanisms all cause a change in allele frequency within a group of organisms. Allele frequency is a measure of the relative frequency of an allele in population;  thus a change in frequencies lead to evolution (Wolf, Lone 2012). In summary, these mechanisms contributed to the development of singled cell organisms living on the ocean bed to many species being present in the environment.
A fascinating example of evolution is the evolution of the dolphin from the mesonix. Around 95 million years ago an animal called the Mesonix (ancestor of dolphin) roamed the earth. It had four limbs and often travelled to the water to feed ( 2012). In the next 30 million years it became more adapted to water due to changing environmental
Text Box:, 2012

conditions (food), genetic drift and possible mutations ( 2012).

The relationship between the Mesonix and dolphin is found through evolutionary development biology (Evo-devo), whereby different species are compared in terms of development process to determine the ancestral relationship (New World Encyclopaedia 2009). In this case, the pelvic bones of the Mesonix and the dolphin are very similar even though a dolphin is missing four limbs; this indicates an ancestral relationship.

Text Box:, 2012It is clear that Darwin’s Theory of Natural Selection and evolution answers and explores many questions of today’s society. However, questions such as ‘Have humans stopped evolving?’ or ‘Are we continuously evolving?’ still remain unanswered. Whilst the future remains uncertain for us, we should be intrigued and thankful that we are on this earth in the first place.


·         Coyle, Daniel 2012, How to get better? Be like evolution, viewed 1 September 2012,
·         Moran, Laurence 1993, What is Evolution?, viewed 1 September 2012,
·         New World Encyclopaedia 2009, Evolution, viewed 2 September 2012,
· 2012, Dolphin Evolution, viewed 3 September 2012,
·         Wolf, Lone 2010, Evolution: Mutations, Natural Selection, Genetic Drift and Speciation, viewed 2 September 2012,

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