Helping Students Think about the Evidence for Macroevolution

Author Tim Barnett Published on 03/15/2016

When I meet someone who claims that evolution is a fact, I have two questions for him. First, I need to find out what he means by evolution. To do this, I employ a variation of the first Columbo question: What do you mean by evolution? The term evolution can be used to mean a number of different things. Therefore, it’s important to find out precisely what they mean.

Broadly speaking, evolution can be divided into two categories: microevolution and macroevolution. Microevolution is the process where small-scale biological change occurs in an organism by selecting some characteristics. Macroevolution, on the other hand, is the idea that all of the diversity of life is descended from a common ancestor through an unguided, natural process.

Second, if this person really means macroevolution is a fact, then I have a follow-up question. I need to find out why he thinks evolution is a fact. To do this, I employ the second Columbo question: How did you come to that conclusion? That is, what do you think is the best evidence for macroevolution that warrants your calling it a fact?

Don’t be surprised if the person gives you a blank stare. As a general rule, most people are not prepared to actually defend what they believe. After a talk I gave recently, a young university student came up to me and asserted that the evidence for macroevolution is overwhelming. Taking my own advice, I asked him, “What do you think is the best evidence?” He responded, “There is too much to even name one!”

I thought that was an odd response so I pushed back, “Well, what do you think is the best one?” He obviously was not prepared to answer my question because he awkwardly hemmed and hawed for about 30 seconds. I broke the silence by pointing out the obvious; he was struggling to defend his assertion.

Not everyone will be caught off guard by your second question. In fact, if they have even a basic knowledge of evolutionary biology, they should be able to point to some purported evidence for macroevolution. This is where your job gets a little more difficult since you may not know exactly how to respond to each particular challenge.

What I’d like to offer you is a helpful way of categorizing the evidence that is offered in support of macroevolution. By identifying which group any particular evidence belongs to, you will be able to offer a general response. After assessing numerous arguments for evolution, I have found that each falls into one of three categories: exaggerated extrapolations, egregious errors, and equivocal evidence.

Exaggerated Extrapolations

This is probably the most common mistake made by evolutionists. It’s a mistaken projection. Evolutionists take genuine evidence of microevolution and think that if they add enough time, they will get macroevolution.

Consider an exaggerated extrapolation found in every senior level high school biology textbook: Darwin’s finches. In fact, many consider this to be an icon of evolution. While Charles Darwin was on the Galapagos Islands, he studied 13 different species of finches. The most important observable differences between these species were the size and shape of their beaks. Darwin concluded that their beaks were highly adapted to different food sources, and that all of these finches share a common ancestor.

Now this may be a fascinating discovery, but it is an incredible extrapolation to go from observed changes in finch beaks to the assertion that this provides evidence that all of life is descended from a universal common ancestor.

An informed reader may want to protest, “Darwin’s finches were never meant to prove macroevolution.” Fair enough. But this is exactly my point. Any example of microevolution is not the kind of thing that qualifies as evidence of macroevolution.

Darwin’s finches provide us with evidence of the powers of natural selection and adaptation. It’s a great example of microevolution-in-action. However, it would be a gross mistake to think that adding time makes this evidence for macroevolution. Macroevolution is a different category; therefore, it needs its own evidence.

Egregious Errors

This amounts to evidence based on mistaken information. They don’t get their facts right. Probably the most egregious error in the textbooks today is the argument for evolution from Haeckel’s embryos. This is a little ironic since Darwin thought this was the strongest argument in favor of his theory. In fact, on September 10th, 1860, Charles Darwin wrote a letter to the American botanist Asa Grey. In this letter, he tells Grey that “embryology is to me by far the strongest single class of facts in favor of change of forms, and not one, I think, of my reviewers has alluded to this.”

What was he referring to? In the late 1800s, German biologist Ernst Haeckel drew a series of embryos from different animals (e.g. a human, a chicken, a salamander, a fish). Darwin argued that these embryos showed remarkable similarity in their earliest stage. As a result, he understood this to be confirmation of his theory. In short, the early similarity of the embryos shows that they shared a common ancestor.

The story may sound convincing, but there’s a problem. Haeckel faked his drawings. Photographic images of these early embryos show that they actually don’t look similar. Moreover, in 1997, the scientific journal Science included a short article titled “Haeckel’s Embryos: Fraud Rediscovered.” In the article, the author states, “It looks like it’s turning out to be one of the most famous fakes in biology.”

If macroevolution is as established as evolutionists claim, then they shouldn’t be using false or outdated evidence. When an egregious error is used to substantiate macroevolution, the best thing to do is point it out. Truth is always the best means of combating error.

Equivocal Evidence

This is evidence that could be evidence of macroevolution, but could also be evidence of intelligent design. So the evidence can be interpreted in different ways. As a result, I believe the evolutionist comes to a mistaken conclusion.

I would put homology in this category. Homology is one of the strongest evidences ever put forward for macroevolution. Homology has to do with the similarity between organisms. Evolutionists understand this similarity to be evidence of common descent. For instance, the human arm, cat leg, whale flipper, and bat wing all have a strikingly similar bone pattern in their forelimb. They each start with one big bone, which is connected to two smaller bones, which is connected to even smaller bones. Finally, there is a five-digit pattern.

Is this evidence for common descent? Well, it could be. But this similarity could equally be explained by common design.

I want to use an illustration to help us get at answering this question. In 2001, Apple launched a new portable media player they called the iPod. Since its release, the iPod has changed over time. There has been the iPod shuffle, the iPod nano, the iPod touch, the iPod mini, and even the short-lived iPod photo. Obviously, there is much similarity between these devices. The question is, what best explains this similarity?

Someone with an overactive imagination could assert that one evolved into the next over a long period of time. Some evolved bigger screens, while others lost their screens. Some evolved color screens, and then color screens evolved into touch screens. A select few even evolved a sophisticated camera.

Of course, no one believes the iPod evolved without intelligent intervention. That is, everyone agrees that the similarity of these devices is due to a common designer: Apple. In the same way, the similarity we find in the bat wing and the whale flipper can be equally attributed to a common designer, who made both.

Therefore, similarity could be interpreted as evidence for evolution from a common ancestor, or creation from a common designer. It’s equivocal evidence.

Now, I actually don’t think it’s a coin flip. In fact, a common designer is a better scientific explanation of both the irreducible complexity we see in certain biological features and the specified complexity we find in the diversity of life. So the designer hypothesis has more explanatory power.

Furthermore, a common designer explains similarity that evolutionists believe is not due to a common ancestor. For instance, evolutionists assert that the whale eye, human eye, and mouse eye are similar because of common descent. But what about the octopus eye? It is also similar to the mammalian eye. Well, evolutionists are forced to conclude that the octopus eye must have evolved completely independent of the vertebrate eye. Don’t miss this. Not only did the incredible complexity of the eye evolve once through an unguided process, but it also evolved multiple times. They call similarity that cannot be explained by common descent convergent evolution. However, a common designer could explain the similarity in these different mammals’ eyes and the octopus eye.

Every evidence offered to support macroevolution that I’ve encountered up to this point fits into one of these three groups. Once you have determined which category the evidence belongs to, you can respond accordingly. Exaggerated extrapolations fail to provide the right kind of evidence, and egregious errors fail to provide the kind of evidence that is right. With these out of the way, the evolutionist is left with equivocal evidence to make their case. The problem is, these can be equally used to make the case for an intelligent designer.