The Perpetual Motion of Evoultion

I.W.'s picture

Isabelle Winer

The Story of Evolution

Paper #1

The Perpetual Motion of Evolution

Today many of the problems people have with evolution stem from their understanding of evolution as being a completely random process.  It is human nature to desire order and direction, which explains why religion with its rules and higher being is such a more comfortable story.  On the other hand, evolution, viewed as “completely random”, portrays life as lacking purpose and direction.  Christopher Schöborn displayed this view when he said, “evolution in the neo-Darwinian sense -- an unguided, unplanned process of random variation and natural selection -- is not [true]. Any system of thought that denies or seeks to explain away the overwhelming evidence for design in biology is ideology, not science.”[1] This understanding of evolution is incorrect; evolution is instead a process directed by the ever-changing environment. The variation made possible by the random mutation of genes is simply the opening that makes evolution possible.

There are two basic processes that together function to allow species to evolve: Genetic Variation and Natural Selection. Ernest Mayr, in his book What Evolution Is, explains the delicate balance struck between randomness and direction when he said:

“At the first step, that of the production of genetic variation, everything is a matter of chance.  However, Chance plays a much smaller role at the second step, that of differential survival and reproduction, where the ‘survival of the fittest’ is to a large extent determined by genetically based characteristics.  To claim that natural selection is entirely a chance process reveals a misunderstanding” (pp 120).

 

Genetic variation, which accounts for the differences among the individuals of a species, is achieved through mutations, gene flow and sex.  Mutations are the only part of the evolutionary process that is truly random, but it is what makes the rest possible. Mutations are errors in the replication of DNA during cell division, but these errors are exceedingly rare because of how remarkably accurate the replication process is.  On average there is only an error in a completed strand of DNA in 1 of every 10 billion nucleotides[2].  It is then through gene flow, the movement of genes from one population to another, and sexual reproduction, which creates new recombinations of genes in the offspring, that mutations are spread through a population.  “A mutation is like a shot in the dark” because it is impossible to predict its affect[3].  It could be advantageous, disadvantageous, or just neutral.  There is no order or system to where the DNA replication process will result in a mutation.  It truly is completely random, but mutations in themselves could not result in evolution.  Without natural selection there would be no evolution.

Natural Selection is based on the assumption that there are more offspring born of a population then can survive based on the resources available.  Therefore those individuals which are better adapted to the environment will be able to survive to produce the most offspring of their own.  Darwin explained this concept in The Origin of Species when he said, “Owing to this struggle for life, any variation, however slight and from whatever cause proceeding, if it be in any degree profitable to an individual of any species, … for, of the many individuals of any species which are periodically born, [only] a small number can survive.” Thus, it is the environment that determines which individuals are better adapted.  When the environment changes so does the direction of evolution.  The classic example of this is the peppered moth.  Over the last two hundred years the evolution of the peppered moth has been closely documented.  Initially a vast majority of the peppered moths were light in color.  Their light color allowed them to blend in with the lichens upon which they typically rested.  During the Industrial Revolution their environment began to change because pollution was killing the lichen and soot was coloring the trees black.  The white peppered moths then became clearly visible on the trees and predators easily spotted them, but the darker moths were less visible. Therefore the darker moths were better equipped to avoid predictors and survive to produce offspring. As the time went on the percentage of dark moths continued to rise. Now, as pollution is being curbed and the lichens are growing back the peppered moths are returning to their light coloring[4].  There is nothing random about it.

            If evolution truly were random then it would never lead anywhere. If it truly were random as to which individuals passed on his or her genes, then every individual would have an equal chance.  Therefore no genes would be passed on at a higher rate than others. There would be no change to the gene pool.  Change over time is the defining aspect of evolution, but the fact that there is change over time proves it is not random.  If evolution is not completely random, then that implies to some that there must be some sort of external guiding force. In fact, an external guiding force is not a necessity. What I think that people have trouble accepting is that ultimately it is evolution that directs evolution.  All organisms are constantly evolving and through their evolution effect the environment, which in turn forces other organisms to also evolve to the new environment. This constant competition fuels an endless cycle of change which then goes on to change the rules of the competition.  Evolution perpetually drives itself and will continue to do so as long as life exists. As Lao Tzu, a Chinese Taoist philosopher, said, “The reason why the universe is eternal is that it does not live for itself; it gives life to others as it transforms”.

 

 

 

 

 

 

 

 

Works Cited

 

1. "Industrial Melanism in Biston betularia." New Mexico State University. 16 Feb. 2007           <http://web.nmsu.edu/~wboeckle/biston.html>.

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

3. "What is evolution and how does it work?" Understanding Evolution. The University of California Museum of Paleontology. 16 Feb. 2007 <http://evolution.berkeley.edu/evolibrary/search/topicbrowse2.php?topic_id=41>.

4. Darwin, Charles. The Origin of Species. 1859. New York: Random House, 1979.

5. Campbell, Neil A., and Jane B. Reece. Biology. 7th ed. San Francisco: Pearson Education Inc. , 2005.

[1] New York Times, 2005

[2] Campbell and Reece, pp 305

[3] Ibid.

[4] “Industrial Melanism in Biston betularia”

Comments

Anne Dalke's picture

perpetually

2/17/07

Isabelle—

This paper is assured in tone, careful in its explanation of the interaction between genetic variation and natural selection, apt in its use of the peppered moth as an example of the deliberate non-randomness of the evolutionary process, inspirational in its final Taoist gesture. All lovely—it makes me think that this sort of measured explanation might go a long way towards reaching religious folk—and/or others discomfited by the notion of “unguided, unplanned randomness.” Do you imagine that the sort of other-directedness evinced in the quote from Lzo Tzu, with which you end, could reach Christopher Schönborn, with whom you begin? Or is there still a gap? Do you think that saying that “ultimately it is evolution that directs evolution” would satisfy those who want a designer who attends to us? (See the Little Monk’s speech, in Brecht’s play Galileo, for the most eloquent defense of this point of view that I know.)

A few further questions:

--given our discussion last Thursday, I’m assuming that your use of “error” in the description of the process of DNA replication was deliberate. Want to riff on that for me a bit? Would you call any failure to replicate accurately an “error”? Even if the failure opens a way for a mutation that proves in some way advantageous?

--I noticed in particular your claim that “it is the environment that determines which individuals are better adapted.” While you’re riffing, could you talk a bit more about how you use/how heavy the “determinism” is in this interaction?

Good work. I look forward to your further thinking.
Anne

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