Evolution 101

      In the past few weeks, I've been reading several debates about intelligent design on several blogs. There were some remarkably uninformed comments from both sides concerning evolution. We'll put aside the whole freedom of speech issue and whether intelligent design should be taught to give a primer on where evolutionary theory stands today. I think both sides will find it surprising. (Wait, keep reading. I promise it's not as boring as it sounds. And one other thing, don't assume that you know where I stand in the debate from this post. I'll be covering my stance and why I believe the way I do later. This post is about information.)
      First, let's start with Charles Darwin. Darwin's theory basically stated that natural selection was capable of producing new species. Here's a definition for you from Princeton's web site: Natural selection is the process in which some organisms live and reproduce and others die before reproducing. Some life forms survive and reproduce because they are better suited to environmental pressures, ensuring that their characteristics are perpetuated. This is also called "survival of the fittest."
      Darwin's idea was that you start with one simple organism, say a finch. Place several finches in different environments like separated islands. Each island has unique characteristics. One island has plenty of water, one island is dry, one has a certain prey species and another has a different prey species. Then you let the finches breed. Over time, finches that have a physical advantage (for instance, a stronger beak that allows them to open clams easier) will survive longer and breed more, allowing their characteristics (stronger beak, hook-shaped beak, etc.) to be passed on to their offspring. You keep this up for long enough, and eventually the various finches on the different islands look different and act different. Allow centuries to pass, and eventually they can't breed with each other anymore. (Read more about Darwin's finches here.) You probably studied this in high school and assumed that covered the theory of evolution.
      But it might surprise you to realize that most evolutionists no longer believe that natural selection is the sole engine of evolution. In fact, some evolutionists think Darwin's theory is quaint and hopelessly outdated and believe his real significance is simply that he raised the idea that a natural process could produce complicated organisms.
      Why would they desert Darwin in this way? Well, natural selection as an evolutionary engine has a flaw in it. Let's consider birds for instance. A current theory has birds evolving from reptiles. It's easy to produce an evolutionary chain that leads to a bat-like creature. (A reptile that jumps well can catch more prey than one that doesn't. It produces more offspring who pass on this characteristic to its young. Young that have larger webs between their toes and lighter bones jump farther. They pass on these characteristics. Eventually you have a reptile that leaps off a rock and then glides. It passes on those characteristics, and so on, and so on.) However, feathers are a problem. Since a parent reptile doesn't have feathers to begin with, why would its offspring? You can create a chain, of course, that leads to feathers, perhaps starting with a parent born with thicker hair and that hair is somehow an advantage which allows it to breed more, and eventually you produce a complicated feather ... But when you add into the adaptations that had to take place to produce such a complicated organism that can fly -- particularly in the time frame in which the fossil record seems to show it happened -- you don't have enough time to do so unless each change was precisely the change needed to produce that feather. (Intelligent design proponents say something had to be directing those changes. This is one of their major arguments.)
      However, since the development of modern genetics in the 1940's, evolution has been defined as a change in the frequency of alleles (or alternative forms of a genetic characteristic) in a population from one generation to the next. In other words, you X-Men fans, mutations!
      Natural selection, however, hasn't been discarded. Today it's thought that evolution is powered by a combination of various things, including genetic drift (the change in frequency in which a gene appears in a population, through mutation, regardless of the adaptive value of the mutation), gene flow (changes in population structure) and ta-da, natural selection.
      Why these changes in evolutionary thought? Because of evolution's biggest problem: time. There's not enough time for natural selection to make the changes necessary. Yes, geologists say the world is billions of years old (4.5 at last estimate), but see, life itself only occupies a small portion of that time, and multi-cellular organisms even less, and man only a tiny fragment. Natural selection is not an intelligent process like a cattleman breeding a better stock. Natural selection has to have time for blunders and dead-ends. And from the fossil records, evolutionists knew they needed something else.
      Enter the late Dr. Stephen Gould who proposed the "punctuated equilibrium" theory of evolution. To quote from the Minnesota State University archives: "His most famous argument for punctuated equilibrium is the panda's 'thumb.' This is a modification of the wrist bone that allows the panda to strip leaves from bamboo shoots which Gould argued must have occurred all at once or it would not have been preserved by natural selection ... Gould wrote a book entitled The Panda's Thumb for which he received two awards, the Notable Book Citation from the American Library Association in 1980, and the American Book Award in Science in 1981." Basically Gould said that rapid change could occur in a species, almost overnight. And the fossil record so far supports this. (Once again, this point is used to intelligent design proponents to bolster their argument. They ask, "After all, isn't it possible that something is directing these sudden changes?")
      At this junction, I should point out that there are many variations on the theory of evolution, and not all evolutionary scientists accept Gould's theory or genetic drift or natural selection for that matter. Some of these battles are quite bitter with name-calling and shoving and general all-around bad behavior. It's a lot of fun to watch.
      Anyway, mutations were proposed as a way for that change to take place. Example: a parent creature doesn't have wings, but its offspring suddenly do. That seems to be our solution, but wait, once again there's a problem. This one is more subtle than the previous one suffered by natural selection, but it still comes back to time. Mutation is a blind process; it has to be if you don't buy into the intelligent design school of thought. Mutations need time to reproduce. And the majority of the mutations will not be beneficial. So to produce new creatures, we need a lot of mutations, and they need a lot time -- once again more than seems to be shown in the fossil record. I say "seems to be shown" because there's a lot of controversy in this. A LOT.
      Some scientists say that the fossil record is misleading and that we don't have enough fossils to really tell when an organism evolved. Others search for more "missing link" organisms, particularly those who are opposed to Gould's theory. Others are working in the labs, decoding genes in an attempt to show that genetics by itself can produce new organisms. And still others discount all of this for other theories or take parts of each theory to use.
      Does it sound confusing? It is. Many people are surprised by all this, believing that science is united by its belief in the theory of evolution. But evolutionists are at least united in this: Organisms change over time. These changes eventually produce new organisms different from their ancestors.
      But what causes those changes? As you can tell, even among evolutionists, that's debatable.