Sunday, December 25, 2011

Evolution and DNA

I recently watched a documentary concerning evolution and recent advancements in our knowledge of DNA.  It was entitled "What Darwin Never Knew".

The documentary pointed out not only that Darwin never knew about DNA but that until recently no one understood certain aspects of its operation.  Most particularly, it has only recently been understood that DNA consists of a series of strands that govern individual aspects of a species' development and that each of those strands comes with a small portion of DNA that governs when it is turned on and off during the development of the particular species.

The features of the species are so sensitive to small changes in the timing of these events that in some cases simply switching on a particular gene 24 hours earlier during fetal development will cause changes dramatic enough that the animal could be considered a separate species.  If several such minor changes occur in a group of animals, then it will be a separate species.

What is significant about this is that it nullifies the creationist arguments that we so often hear about the rarity of actual mutations in genes and how mutations usually result in harmful changes.  The facts of this argument are true, true mutations (where the DNA strand has been damaged or altered) are relatively rare and usually harmful.

Now we know, however, that mutations are not the only possible way in which evolution can occur.  Simple minor changes in the timing of the development of features during gestation can cause noticeable differences.  Those changes can be the result of genes switching on or off at slightly different times, which can be the result of minor, normal differences in the genome.

Such differences occur every time animals engage in sexual reproduction.  The process of splitting each parents genes in half is not exact.  Virtually every sperm and every ovum carries a different portion of the parent's DNA from all the others.  When recombined with an equally randomly chosen portion of the genes of the other parent they create a new and unique individual that often has traits that diverge from those of one or even both parents.  Anyone who has children or has observed those who do, knows that such differences between parents and children often occur.

Perhaps I should add to the last sentence of the preceding paragraph "If the person is paying attention".  I have noticed that many people, particularly religious people, seem to have a livestock breeder's view of genetics.  They think that children directly inherit the traits of their parents because pigs give birth to pigs and horses give birth to horses.

I have noticed that such people are often quite upset when their own children are not "just like" them.  This is especially true if the trait they expected to see is the one they are most vain about in themselves.  Their child may have unique or even spectacular talents or gifts, yet if those are not the talents and gifts the parents had, they may be completely unappreciated.

Sad as these little family tragedies may be for the individuals involved, they help us understand the depth of the ignorance of the average person concerning genetics and the reproductive process.  Which, in turn, helps us understand the persistence of creationism.  If one must engage a creationist, then it is a good idea to give him or her a small education concerning genetic recombination in the reproductive process.

I wouldn't recommend spending too much time in such endeavors, however.  Creationists are inevitably fanatics who are ignorant of many aspects of science.  The most one should ever do or hope to do when speaking to one of them is to point them in the right direction concerning one or two of their misconceptions.  After that, change the subject or leave.  Further debate will simply upset them and cause them to dig in their heels.

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