Evolution. This nasty E-word has become very vitriolic among certain circles within the United States. Last week the Alabama state board of education voted to keep a disclaimer asking students to question the theory of evolution in specific biology textbooks that included the theory of evolution. The vote was unanimous for keeping the disclaimer in.
The disclaimer states that the theory of evolution is “controversial because it states natural selection provides the basis for the modern scientific explanation for the diversity of living things.” The disclaimer goes on to state that the theory of evolution makes assumptions without direct observation of large-scale change. I generally try to stay neutral towards topics in which a side can be taken, but I have some issues with this.
While encouraging children and students to question and seek answers to things they do not understand is commendable, the disclaimer above is not. It calls into question the word theory, saying it “has many meanings.” In an every-day context, this is true. However, in the field of science, theory means one thing and one thing only. A theory is not just an idea someone has about something, the way we normally use it.
The word theory in science means specifically a hypothesis which has been tested rigorously and is supported with evidence. It is in no way just an idea someone had one day, it is something that has been studied and tested repeatedly, but not only that! It is something that has held up under scientific scrutiny. By saying that the word theory has many meanings, the disclaimer in those textbooks has already misinformed children who read the text in the first place. Within the context of science, a theory has only one meaning, there is no confusion there.
The disclaimer goes on to name scientists such as “Copernicus, Newton, and Einstein” and claim that scientists like these “provided a basis if our knowledge of the world today.” This is an excellent example of why the disclaimer is problematic in regards to science education. Gravity and relativity are both scientific theory, meaning they have been tested and studying extensively.
The disclaimer makes no mention of these theories, but calls the theory of evolution “controversial.” The basis for the argument being made is that the word theory is flexible, and therefore, subject to scrutiny. If that holds true for the word theory across the board, why then do theories like the theory of gravity and the theory of relativity remain unquestioned? Sadly, the answer is a lack of information, or willful negligence of that information.
The disclaimer states “since natural selection has been observed to play a role in influencing small changes in a population, it is assumed that it produces large changes, even though this has not been directly observed.” This statement reflects a misunderstanding of the theory of evolution through natural selection. The idea behind natural selection is quite simple.
An environmental force is put on a species that make it difficult for that species to survive. Because not all animals are identical, some may have developed a random genetic mutation that gives them a slight advantage at surviving this force. The animals with a favorable mutation are more likely to survive, and are therefore more likely to reproduce. Now the offspring of the mutated animal have this same trait, meaning their ability to survive is increased. This continues over multiple generations and suddenly the species looks quite different.
Via Wikipedia
A wonderfully simple example of natural selection can be found in a species of moth called the English Peppered Moth. During England’s industrial revolution there was a species of moth that lived in and around newly industrialized cities. The moths were naturally colored white with small black spots, like pepper. Once the industrial plants of England began spewing soot into the air the countryside soon became blanketed, turning the landscape dark and black. The moths had developed their white pigment as a camouflage, hiding on the white trees in the area.
Now, suddenly the white camouflage made these moths incredibly easy to see, and birds began preying on them more and more. However, just as not all humans have the same hair color, not all of the moths were a stark white color. Some of the moths had a darker pigment, making them a bit harder to spot. The whitest moths were quickly killed off, leaving only darker moths alive. The darker moths have now survived long enough to produce offspring.
The genetic makeup that made those moths slightly darker is now passed on to a new generation, meaning we now have only slightly darker moths. The birds adapt to continue using the moths as a food source, and now the lightest of these new darker moths are killed off in round two. Thus, the darkest of the darker moths survive to reproduce again. Now we only have dark moths.
This cycle continues, with the moths least able to hide being killed and the rest surviving, and eventually the white peppered moth is now a perfect sooty black color, able to hide from predators better than ever. The term natural selection is a poor name in my opinion. Selection implies choice, which is not what happens here. A random event caused certain members of a species to have a higher probability of survival, making their genes more likely to survive and continue, changing the species.
Via Wikipedia
The reason this is a good example is that it shows how quickly evolution can work. This is not speciation, the act of becoming a new species; but it is natural selection. The idea behind speciation, or long-term natural selection, is that given millions of years any species is likely to undergo changes like the moths did, but they tend to be less dramatic. The moths changed quickly because moths breed quickly and the environment changed dramatically.
Usually, change happens much more slowly, taking millions of years. This is why it is disingenuous to claim large scale natural selection has not been observed. It cannot be observed because it takes too long for us to properly document. You may be thinking “But Zach, does that mean the disclaimer was right?!” No. We can still see evolution occurring on a large scale. Fossils are a perfect indication of this. We can see various different species and their transitional forms laid out. There are gaps in the fossil record, but the idea that evolution is akin to what you would see in Pokémon is ridiculous.
A human will not one day give birth to something with wings or scales or sharp teeth. That is not what the theory claims. Evolution does not happen instantaneously, where one generation looks like one species and then gives birth to something completely different. Evolution occurs in tiny changes, like pigment color, that over time, eventually make the species look very different from others of its kind. Given enough time, these tiny changes add up and species begin diverging.
Ultimately the disclaimer is damaging to scientific learning simply because it mischaracterizes evolution and claims it is controversial from the get-go. The disclaimer incorrectly claims that the word theory has many meanings, which it does not in a scientific context. It uses words like “assume” and “controversial” to undermine the theory of evolution through natural selection by making it seem as if the jury is still out on whether or not evolution is a legitimate theory. It is not; evolution has hundreds of pieces of evidence.
The disclaimer also claims that large-scale evolution has not been observed, which fails to grasp the entire concept of evolution. The danger with these sorts of things is that it fails to understand the difference between science and someone out in the world just coming up with ideas. Understanding why the scientific process is a more reliable way of knowing is vital to operating in the 21st Century.
