The meaning of the word

I guess that before I start telling tales, I should make sure people understand what I'm talking about.  Like any field, biology is full of jargon - specialized terms used to describe what's going on.  Biologists spend an inordinate amount of time debating what those words actually mean.  So here's my disclaimer:  any jargon I attempt to define in this blog is my own interpretation of what a particular word or phrase means.  There may exist alternative interpretations.  I'm not a lawyer, I'm a biologist.

So let's start with the obvious - evolution.  Simply put, evolution is change over time in the DNA of a population of interbreeding individuals.  I tend to favor talking about evolution in terms of changes at the DNA level, because I'm a molecular evolutionary biologist, and I think it's easier to understand that way.  Now there are a couple things that evolution is NOT.  

Evolution is NOT:

- directed.  There is no goal, no plan.  Evolution is like taking a random walk without a map.  You don't know where you're going and you might have a faint idea of where you came from.

- progressive.  All organisms are equally advanced.  There are not higher plants and lower plants.  Flowering plants, because they are more recently derived, are not "better" than algae, which share a common ancestor with flowering plants.  It is only fair to describe things in terms of increasing complexity.  

So to me, if you say you don't believe in evolution - then what you're telling me is that you think that the DNA of every organism on this planet is the same as it was at the beginning of time.  Now, I ask you - do your children have the exact same DNA as you, with absolutely no changes?  If your answer is yes, well then I'm afraid males shouldn't exist in your world.  The basic idea behind evolution is random change in the genetic material that is passed from one generation to the next.

Now I think the only world people would disagree with in that statement is the word random.  If you think all change is directed and progressive, then you don't agree that the process is random.  I guess my challenge is to supply evidence for the random nature of evolution.

There are a lot of different processes that result in evolution, starting from the mechanisms of mutation and recombination to evolutionary forces such as natural selection and genetic drift.  So that's what I'll talk about in my next posts.

Frozen accidents

There's a term used in evolutionary biology - "frozen accidents".  Generally it means that the state of something in biology is the way it is just because it's the way it is - that there is no overall purpose or benefit for something being done a certain way.  It's an accident of evolution, and it's just stuck, or frozen, because we're so far down the line that changing it would be near impossible - that natural selection, or any of the evolutionary forces are not sufficient to make it any better.  

The first example of this I was introduced to was the genetic code.  The genetic code is a series of 3 letter "words" or strings of individual bases of DNA that are translated into a particular amino acid (the building blocks of proteins).  Throughout life on earth, the genetic code is the same for the vast majority of organisms (mitochondria and a few organisms have different codes, but they're very close to the "universal" genetic code).  The genetic code is redundant - multiple words translate to the same amino acid.  However, there didn't seem to be any explanation for why certain DNA words stood for particular amino acids.  This was a frozen accident - the vast majority of life on earth has the same genetic code because we have a common ancestor that had this code, and since it's such a vital part of how things work, it's hard to change it.  If you change the code in any one organism, you would end up changing the makeup of all the proteins in the cell, and they most likely wouldn't function properly anymore.  So we're stuck with a genetic code from a couple of billion years ago.  Fortunately, research hypothesizes that this code is actually fairly optimal - it minimizes the impact of the most common mutations.  Amino acids have basic chemical properties - some like water, some stay away from water (like fats), some are basic, some are acidic, etc.  The genetic code is such that a common mutation in the DNA is more likely to change the amino acid that's coded for to another amino acid that acts kinda like the original amino acid.  But researchers found that if this is the reason for the genetic code being the way it is, it isn't the best it could be.  

And that's kinda the point of this blog - to discuss topics in biology in sync with their evolutionary origins and how those origins aren't really founded in "intelligent design" because if there was a designer and that designer was intelligent, that designer would have done a better job.

As far as I'm concerned, I hold a Ph.D. in Biology, specializing in Molecular Evolutionary Biology.  I'm a practicing Roman Catholic and I manage to believe in God and still think that evolution exists.  My purpose is education - because if people are going to spread the word that evolution doesn't exist, I'm going to fight back by teaching people how evolution does exist and why it's really the best explanation anyone has for the beauty and diversity of the life that surrounds us.