Defining Evolution

Had an interesting conversation with my dad last night that made me think it might be useful if i tried to distill some ideas here. Its a jumble of ideas that are all related to the subject of evolution and the controversy that academics get into with the public - one of these debates is about if evolution should be taught in school, but it isnt the only one. My position is that most people don't understand what evolution is (and academics seem to not be interested in educating them about evolution per se) and that most evolutionary biologists have very hostile feelings towards intelligent design advocates and the rest of the religious world by extension (and that hostility is enflamed by political preferences). Neither of these is a good recipe for reasoned exchange. Some of these thoughts will tie directly to those issues, and some more indirectly.

I think that one of the biggest problems is a desire (by both the academics and the lay) for a sound byte definition of evolution. Survival of the fittest is a commonly used phrase, but it puts an improper focus on survival, lifespan, and appealing traits (i'm thinking something like, for humans, athleticism and muscular build) since fitness in our vernacular is different than the specific definition assigned to the word by biologists. In biology, fitness roughly means the success of an organism at passing on its genes. Further, the word survival applies to the forthcoming generation, not the current one. Evolution is barely interested in the survival of the current generation once they have reproduced, and is almost exclusively focused on the ability of the new generation to reach the age of reproduction and reproduce. Therefore, to be consistent with the vernacular, "survival of the fittest" could be rephrased as, "Propagation of the reproducers" or simply "Reproducers reproduce". But to be more to the point we should define the word, "allele."

Genes are made up of variants called alleles. A common example is eye color - i may have blue eyes and you may have brown eyes, and this results from differences in our genetic makup. Briefly, an allele is a different variety of any given gene - it will be located at the same location in the chromosome, but the sequence of the DNA for each allele will vary, usually slightly. These small changes cause small variations in the characteristics that each gene is responsible for. For example, eye color varies because of different alleles - the allele responsible for blue eyes, brown eyes, etc - but we all still have color to our eyes. It is usually a subtle, not a major change. These alleles are really what evolution is interested in.

Armed with the knowledge that alleles are slight variants of gene sequence for any given gene, and that alleles may cause changes in the characteristics of the individuals who have those alleles in their DNA, defining evolution is simple: "Evolution is the change in allele frequencies in a population over time." the key concepts are CHANGE, FREQUENCY, POPULATION, and TIME.