SCIENCE FOR BIBLE BELIEVERS
Natural Selection
The theory of
natural selection is much more complicated than the theory of evolution, and it is much less obvious that it is true. My objective in this chapter is only to teach you the theory of
natural selection. I will make no attempt to convince you that it is true until later chapters. Since this theory is difficult to understand, I ask you to focus on learning what it is without distracting yourself by trying to argue with it.
Natural selection is a probabilistic theory. It doesn’t make any promises. It offers no guarantees. It only tells you what will
probably happen in a given situation. That’s the part that you’re missing if you say, “The species that exist today couldn’t have been created by rolling dice.” So I’m going to have to teach you some basic probability theory. If you’re a mathaphobe, be brave. I will limit the lesson to the least you need to know. Once you understand the probabilistic nature of
natural selection, you will probably (so to speak) stop believing that
natural selection is totally unreasonable and begin believing that it is possible. Then, when I present the evidence in favor of
natural selection, I anticipate that you will agree that
natural selection actually happened on this planet. And then
later, I’ll offer you some arguments against
natural selection that you can present to
Job.
Throughout this chapter, I’m going to have to say, “it is very probable that” many times. To avoid annoying you with this redundancy, I will use orange font when I mean that something is very probable. For example, if you roll two fair six-sided dice a million times, you will roll seven more times than any other number. It is certainly possible to roll twos a million times in a row, but the probability of that happening is less than 0.000…0001%, with more than 600,000 zeroes. However, it is very probable that you will roll sevens more times than any other number.
So, this is the theory of natural selection: If more than one type of
creature’s reproductive tactics are the same,
the one that is most environmentally fit will increase in population, while
the others will eventually go extinct. So now I need to explain what I mean by
“reproductive tactics” and
“environmental fitness”. When I say
reproductive tactics, I’m talking about the way a
creature behaves in order to reproduce. For example, a giraffe’s
reproductive tactics include eating leaves (to avoid starvation) and running fast (to avoid being killed by predators). And
environmental fitness specifies the probability that a
creature will survive to reproduce. So, for example, if two types of
creatures have the
reproductive tactic of fleeing from the same predators, the one that runs faster is more
environmentally fit than the other one, so it is more likely to survive long enough to reproduce. (This reminds me of a joke: Two men were being chased by a cheetah. One of them said, “It’s no use. We can’t outrun the cheetah.” The other responded, “I don’t have to outrun the cheetah. I just have to outrun you.”)
So, you misunderstand the theory of
natural selection if you think it’s all about randomness. It’s not
all about randomness. It’s about probabilities. So before I say any more about
natural selection, I’ll tell you the least you need to know about probabilities.