The Probability of Evolution: The Real Argument

Most atheists and many people who believe in God believe that all life on Earth today evolved from one organism hundreds of millions of years ago. This belief is usually referred to as “evolution.”

But what exactly is evolution, is it true, and why is it important?

Common ancestry is the core belief of evolution

Let’s start off with a definition. Evolution is the theory that all life on earth originated with a common ancestor, and evolved through random genetic mutations and natural selection. The key thing to remember about evolution is the idea of common ancestry.

The National Center for Science Education — one of the leading pro-evolutionist organizations in the U.S. — calls common ancestry “the core tenet of evolutionary theory—that all living things are genealogically related.” Always remember that common ancestry is the core belief of evolution.

When discussing or debating evolution, a proponent of evolution will often try to slyly change the definition. They will say something like, “Evolution is change.” This is bogus prima facie because if evolution meant “change” no one would use the word “evolution.” One is one syllable and the other is four syllables. Obviously, there is much more to the theory of evolution than just change.

What about the other two concepts of evolution — random genetic mutation and natural selection? Both of these processes are known to occur and have been observed.

We know that genes can become corrupted, and the information in those genes can be lost due to random mutations. These mutations could occur due to exposure to radioactivity, a chemical, or for an unknown reason.

Natural selection is a buzzword that pro-evolutionists often try to equate with the theory of evolution itself. Natural selection is the idea that an organism which reproduces will pass its genes onto its offspring, while an organism that is not able to reproduce will not. No, I’m not kidding. Natural selection is a tautology — a different way of saying something that has already been said or implied.

If you listen to biologists carefully, you’ll hear them say that something “selects for” a particular trait. What they mean is that a particular behavior or process helps to facilitate reproduction for organisms that have that particular trait.

Here’s an example: A certain type of fish swims faster and is more adept at escaping predators than other fish. Since this fish is less likely to be eaten than other fish, he is more likely to reproduce than they are. This fish reproduces, and passes on his fast-swimming genes. Thus, we say that natural selection “selects for” this type of fish.

So how does natural selection and random mutation fit into the core tenet of the theory of evolution — common ancestry? It’s all about making a blind leap of faith.

Evolutionists believe that, starting with a single living organism, random genetic mutations conferred various traits to that organism. That organism reproduced, and those offspring reproduced, and so on. As the “family tree” grew, genetic mutations occurred in some of the organisms, resulting in billions of small changes (Darwin called them “gradations”) in those organisms. Evolutionists believe that those changes accumulated over time, and eventually led to the enormous variety of life we see today.

It’s important to remember that the theory of evolution starts with life and genetic information. It doesn’t attempt to explain the origin of the first living thing. It assumes it.

I said earlier that you should always remember that the idea of common ancestry is the core tenet of evolution. Why do I say this?

Because many, many people who believe in evolution do not know that common ancestry is at the heart of the theory.

The idea of common ancestry is counter-intuitive. In other words, it does not “feel” right. Consequently, even some people who claim to believe in evolution subconsciously reject common ancestry without realizing they are undermining their own belief!

But just because something is counter-intuitive doesn’t automatically make it untrue. So is evolution true? I will get there, but first there is another question to consider: Does it really matter if evolution is true or not?

Theistic Evolution

I mentioned at the beginning that both atheists and theists believe in evolution. Even many Christians say that you can believe in the Bible and evolution. Christians who put forth this idea often say that Genesis can be taken figuratively, where a “day” can mean millions of years and the account of Creation can be taken as a metaphor for evolution.

Without reinventing the wheel and getting into an exegesis, let me assure you that the account of Creation is literal. A “day” means a literal, 24-hour day. The Genesis account of Creation is not a metaphor for evolution. (If you want an exegesis, read Douglas Hamp’s article)

More importantly, if Genesis cannot be taken literally, why should we take anything else in the Bible literally? This is the exact argument atheists use to discredit the Holy Scriptures. Atheists and sundry heathens are so desperate to promote evolution as “fact” because it single-handedly undermines the entire Bible and, by extension, the Gospel of Christ.

Now, it’s time to answer the final question: Is evolution a fact?

Earlier I said that the theory of evolution does not explain the origin of the first living organism. The theory assumes the first living organism already exists, along with DNA and the ability to reproduce. This concept is key to developing an argument to crush the theory.

There are two other key concepts you should understand: Genetics and probability. Don’t be intimidated by these because they are really actually very easy to understand.

Let’s start with genetics. Every living thing contains a set of instructions for how to carry out various tasks, like how to build a protein molecule. These instructions are stored on genes, and each “letter” of each instruction is called a base pair.

There are only two possible DNA base pairs called AT and GC. This means that the instructions are written using a two-letter “alphabet.” (This is actually the same way computers store information.) An instruction for building a protein might be a few hundred base pairs long. There could also be base pairs (“letters”) that do not contain any instructions at all. And there could also yet be base pairs that, if you read them “left-to-right”, contain instructions for building one type of protein, but if you read them “right-to-left,” contain instructions for building a completely different type of protein! (Try doing that with instructions on paper!)

Understanding Probability

The next key concept is probability. Probability is easiest to understand by giving an example. Since we just touched on genetics, we’ll use an example from that. Suppose you have two possible base pairs, AT and GC. If you randomly select one of them, the probability that you will select AT is 1 in 2, or 50%. Don’t worry if you don’t feel totally comfortable with probability yet. Once I get into the argument against evolution, it will make a lot more sense.

David H. Bailey, an evolutionist at the Lawrence Berkeley National Laboratory, and a Mormon, wrote a paper called “Evolution and Probability.” In it he cites an argument from David Foster’s book The Philosophical Scientists that claims that the probability of the alpha component of human hemoglobin evolving from random mutations is so low that it’s practically impossible (hemoglobin is the part of your blood that carries life-sustaining oxygen).

Bailey points out that Foster’s probability-based argument against evolution contains a very serious flaw. The supposed flaw is the assumption is that the entire alpha component would have to be produced by a random process. Bailey says that the alpha component of human hemoglobin is identical to that of chimps, and almost identical to that of gorillas, and therefore would have had a very high probability of mutating into the alpha component seen in humans.

He writes:

In more distant vertebrate relatives, the alpha hemoglobin chain differs by 25 amino acids between humans and rabbits and by about 100 between humans and various fish species… Revising the probability calculations used by Hoyle and Wickramasinghe from this point of view — that only about 25 particular locations must be correct to enable the oxygen transport function…

The preceding quote is a great example of the logical fallacy of “begging the question” or assuming the premise as the conclusion! The probability figures Bailey calculated for the evolution of human alpha globin assume evolution! Bailey then uses these new figures to conclude that the probability of the alpha component arising from a random process is much greater than Foster claimed.

Well, Bailey and Foster are both wrong.

The production of the alpha component is not a random process. It is based on instructions contained in DNA! Evolutionists do not assume and do not argue that the alpha component was produced through a random chemical process.

What evolutionists do argue is that the DNA instructions required to make the alpha component are themselves the product of random mutation and natural selection.

Therefore, arguing that the alpha component can’t arise from a random process is the wrong argument!

Consider this question: Which is less likely, the random assembly of a Rolex watch, or the random assembly of instructions to build a Rolex watch?

The random assembly of instructions is less likely, simply because many more things have to “fall into place” for that to happen.

The same principle applies to the production of the alpha component. The generation of the instructions to build the alpha component by random assembly is far less likely than the alpha component just coming together by a random chemical process.

So the next question is: what is the probability of the instructions for the alpha component coming together by a random process?

To answer this, we need to understand a little bit about human hemoglobin synthesis. There are two important components of human hemoglobin: the alpha component and the beta component.

The alpha component is coded for by the HBA1 and HBA2 genes, and the beta component is coded for by the HBB gene. Here’s the thing: HBA1 and HBA2 are almost identical on the instructions that are vitally important (the portions that code for proteins). Therefore, we will throw out HBA1 and just focus on HBA2.

HBA2 contains about 605 base pairs that code for proteins. As a reminder, a base pair is one of two “letters”, either AT or GC. These are more base pairs on HBA2, but we only care about the ones that are really necessary. Why? Because we want to give the theory of evolution the best chance possible. We do not want to assume that every base pair is equally important. We just want to “count” the ones that we already know are necessary.

Now that we know the number of base pairs for HBA2, we can calculate the probability that those base pairs would arise by a random process. There are only two possible base pairs, and 605 places for each base pair. Thus, the probability of the DNA instructions for the important part of alpha globin arising naturally are 1 in 2^605 or 1 in 10^182 (that’s 10 raised to the 182nd power, or 10 with 182 zeros after it).

To give you an idea of how large a number that is, compare it to the number of atoms in the known universe: 10^80.

But we are not done yet.

For hemoglobin to be useful, we also need the beta globin component. Instructions for building beta globin are stored in the HBB gene which has 502 base pairs that code for proteins. The probability of the important base pairs in the HBB gene arising randomly are 1 in 2^502 or 1 in 10^151.

But what is the probability of both HBA2 and HBB’s important base pairs being produced by a random process? 1 in 2^1107 or 1 in 10^333.

But is 1 in 10^333 the same thing as impossible? Mathematically, no.

But alpha and beta globin are just a part of hemoglobin (not even the whole molecule). We still have to code for the tissues that make up blood vessels. And then there’s the other important components of blood.

Now, I need to address an objection that I know will come up. Some will say that I am selectively picking the hemoglobin example because it helps my argument. But which example I pick is completely irrelevant. The evolutionists themselves could pick the example, and it wouldn’t make a bit of difference. Why do I say this?

First, any example has to match the staring assumptions of evolution. It must have reproducing life and DNA (or RNA) with its base pairs. It must have random mutation. My hemoglobin example matches the starting assumptions of the theory of evolution, but anyone could pick a different example as long as it meets the above criteria.

Second, you’ll recall that the theory of evolution requires billions (at the very least) of small changes. The theory also requires a common ancestor with which these changes all started. No matter what example we use, we have to calculate its probability all the way back to the common ancestor in order to get an accurate picture of how likely it is that the theory is true.

So let’s be generous. Remember, we want to give evolution the best chance possible! We want to believe!

The average gene contains 1,350 base pairs. Let’s be very generous and say that only 1/10 of these base pairs are actually vital. That leaves us with 135 base pairs per gene on average. That gives us a probability of 1 in 2^135 or 1 in about 10^40 of any particular combination of base pairs occurring.

Let’s extend our generosity even further and say that evolution doesn’t need billions or even millions of small changes. Let’s say that only 1,000 changes have occurred overall. These ridiculously generous assumptions give the current theory of evolution a probability of 1 in 2^135,000 of having occurred.

If we wanted to be realistic, we would end up with something like 1 in 2^135,000,000,000. That’s 1 in 2 raised to the 135 billionth power! But, despite such inconceivably low probability, will an evolutionist concede that evolution did not happen?

Evolutionists tend to reject a probability-based argument on the grounds that improbable events happen all the time.

In his paper referenced above, Bailey included pictures of two beautifully unique snowflakes and said that the probability that one of them would form was an extremely improbable event, with a probability of 1 in 10^2500. He writes, “What are the chances that one of these structures can form ‘at random'?” And goes on to say that, despite such odds, a snowflake still formed. He concludes that, since snowflakes form all the time, despite such low probability, that a low probability of evolution does not discredit the theory.

The problem is that this is a Straw Man argument and a misrepresentation of what we are measuring the probability of.

What is the probability that a snowflake will form? Well, in a nice snowstorm, the probability is 1 in 1, or 100%. It is certain!

But what is the probability that one particular, unique snowflake will form? Very, very low.

Bailey’s Straw Man argument assumes that the probability of any snowflake forming is comparable to the probability of a correct alpha globin molecule forming! Obviously, it is not!

For hemoglobin to even function, a functional alpha globin molecule has to form. It can’t just be any old alpha globin molecule. But for a snowflake to be a snowflake, well, it just has to form.

If we were to fix his snowflake example to make it analogous to evolution, we might change the question to be: Given a sketch of a hypothetical snowflake, what is the probability of a real snowflake forming that will look exactly the same?

Evolutionists like to point out that evolution happens “all the time.” Again, this is them shifting the definition of “evolution” to simply mean “change.” Of course change occurs all the time, just like snowflakes occur all the time.

Evolutionists tend to be very, very bad at logic. It is not because they are incapable or even ignorant of it. Rather, it is because the assumption of evolution is so ingrained into the evolutionist’s thought processes that he usually doesn’t even realize he is assuming it.

This is why it is vitally important for us Bible-believing Creationists to remain alert to the assumption of evolution in the unbeliever’s thinking. It may seem obvious to say that an evolutionist believes in evolution, but the truth is that the evolutionist often bases his belief in evolution on the assumption of evolution! We must be ready and willing to point out such circular reasoning and correct it.

So, does the inconceivably low probability of evolution mean that it did not occur? Probability alone cannot tell us that. As long as there are unbelievers bent on rejecting God, there will be those who claim that evolution defied the odds.