Does this idea explain why animals have certain ways of learning or behaving to find a mate? How about the other physiological adaptations? Is it the mutations and genetic recombination that cause heritable variations (as evolution is understood) or is it the constant change in behavior due to environmental conditions that is the "primary vehicle of evolution" (161)?
Thursday, March 22, 2012
Argument- Regulating Environment
Shenk summarizes Monsieur Lamarck's discovery of epigenetics as, "what an individual does in his/her life before having children can change the biological inheritance of those children and their descendants" (161). This is basically saying that heredity does not come from genetic makeup alone, but also from lifestyle and environment patterns; therefore, natural selection is not as random as it once seemed.
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Changes in future generations can come one of two ways. The first is the more classic view of evolution. In this view, the change in future generations is the result of a certain advantageous quality. This quality causes the survival rate of animals with this characteristic to be higher. For example, "snakes have movable bones in their upper jaw, allowing them to swallow food much larger than their head" (Campbell 481). This is a trait that would be advantageous to survival, and therefore, passed down over time. While the change from a hinged jaw, to a movable jaw, wouldn't happen over one generation, a genetic change does occur. The other type of change that can occur over generations has a similar effect. This type of change is what David Shenk writes about in his book. In this type of change, the changes that are passed down are the result of environmental factors that cause changes in DNA. This results in some of these alterations to be passed down to future generations. This will also cause genetic change in future generations.
ReplyDeleteComplex mental features, are the result of factors that are unknown to humans. What we do know, is that behavioral and physiological adaptations are the result of both types of changes. The organism born with a certain trait is more likely to survive, but its exposure to the environment also will alter its genes to make it more likely to survive. These two types of change working together accelerate evolution.
The two types of change work together to cause evolution. This is confirmed by the statement made by geneticist Eva Jablonka: "DNA is not the be all end all of heredity" (161). This is because environmental factors are constantly changing genes. Evolution does not occur in a perfect line. There are offshoots. The offshoots may grow, or they may turn into a dead end. The process speeds up and slowdown. It is not perfectly linear because of the dynamic ways of genes and their interactions with the environment. According to the University of Utah genetics page "The genome dynamically responds to the environment". This causes change to be the result of both "heritable variations" and "environmental conditions"
University of Utah Link:http://learn.genetics.utah.edu/content/epigenetics/
Jonah May (Jonah2020@aol.com)