Story of Evolution, Evolution of Stories
Bryn Mawr College, Spring 2004
First Web Paper
On Serendip

I have always equated the theory of natural selection with the 'survival of the fittest', assuming automatically that nature weeded out those that were not intelligent or strong enough, finally leaving humans at the top of the evolution ladder. After taking this course, my concept of the ladder has changed. Instead of viewing it as vertical, I now conceive of it as horizontal, with all that is currently in existence on earth sharing the place where I believed human beings stood unchallenged. I have gained a deeper and more subtle understanding of the concept of natural selection, understanding how it works in conjunction with other natural processes to affect evolution. The stories that we have discussed in class have changed my story. They have especially changed the vocabulary that I use in order to describe evolution.

An adolescent interest in dinosaurs led me to believe in the theory of catastrophism. "Catastrophism is the theory that Earth has been affected by sudden, short-lived, violent events that were sometimes worldwide in scope." (http://en.wikipedia.org/wiki/Catastrophism). One such catastrophic event occurred 65 million years ago when an asteroid struck earth, wiping out 70% of the species then present on earth. What I failed to understand when I first heard of this asteroid, was that this catastrophic event was a result of random chance, and if it had not occurred one can only conjecture about what shape evolution would have taken.

My story of evolution is now rooted in the way that my definition of natural selection has changed. I no longer view it as the 'survival of the fittest', instead understanding it to be a two step process. Natural selection is best described to be both a random and a non-random process. Mayr calls the first step the "Production of Variation:

Mutation of the zygote from its origin (fertilization) to death; meiosis with recombination through crossing-over at the first division, and random movement of homologous chromosomes during the second (reduction) division; any random aspects of mate choice and fertilization." (Mayr 119)

By this description of the first step of natural selection, Mayr claims that chance plays a big role in evolution. From his explanation, it is possible to understand that even though dinosaurs were the largest creatures on earth, chance played a role in their extinction. Thus chance occurs in natural selection from mate-choice to fertilization and more.

The second step in natural selection is described by Mayr as:

Superior success of certain phenotypes throughout their life cycle (survival selection); nonrandom mate choice, and all other factors that enhance the reproductive success of certain phenotypes (sexual selection). (Mayr 119)

Thus Mayr believes that survival selection, which is adaptation to environmental conditions, as well as sexual selection, competition amongst males to impregnate females, are both nonrandom aspects of natural selection. It is interesting to note that Mayr uses the word "superior" when describing the survival success of an organism. By the use of this word, Mayr is indicating that the species that survive are in some way better than those that do not. His use of this word undermines the role of random chance that he describes as the first step of the process of natural selection. If Mayr claims that an organism that is "superior" or of a higher order than another organism has better chances of survival, then he is describing the evolution of a species as "an intrinsic drive toward a definite goal, particularly toward greater perfection" (Mayr 77). This description is of the essentialist theory of evolution which Mayr claims to shun since it implies that a species has an essence or trait that makes it strive toward survival. My definition of evolution as 'survival of the fittest' also leaned toward essentialism. I too believed that the species with the greatest drive and most intelligence would survive. It is only after reading Mayr and critiquing his text in class, that I have come to create a story of the role of natural selection in evolution.

Even though a novice to Darwin's theory of evolution, I am aware of our genetic transition from an elemental gene pool. Mayr's text documents the evolution from protozoans to more complex organisms, such as humans. This concept of universal common descent is fascinating in its inherent implication that all natural species are actually derived from one specific gene pool. It is this theory that challenges my very concept of a vertical evolutionary ladder. The diagram of the evolutionary tree that was
shown in class by Professor Grobstein, indicates that all species currently in existence stand on an equal level. An understanding of this diagram finally convinced me to change the way in which I described evolution.

I now have a more nuanced understanding of the potency of evolution and how it undermines my initial belief of humans as superior beings. Charles Darwin concluded his On the Origin of Species by saying: "There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved." Darwin uses the present tense when he says that the most beautiful and wonderful forms "are being" evolved. My story is currently being revised and I no longer use the words 'superior' and 'best' when talking about evolution.

Bibliography

1. Mayr, Ernst. What Evolution Is. New York: Basic Books, 2001

2. Wikipedia: The Free Encyclopedia. http://en.wikipedia.org/wiki/Main_Page


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