Teaching Evolution

This was posted on the Daily Kos blog a week ago. Daily Kos is a liberal action group, a point that is notable for a particular reason. How come this kind of thing does not get posted by conservative groups?

I’m a middle school Science teacher.  I teach 6-8th grade Science, namely Earth Science, Biology, and Physical Science in that order.  Part of the Biology curriculum is evolution.  This is no surprise: modern Biology makes no sense whatsoever without Darwin’s Theory of Evolution and Natural Selection.  Literally, it would all be a gigantic illogical nightmare if evolution is left out of the equation.  How would you classify animals?  How would we be able to explain interactions between species in their natural environment?  How could we make sense of the inner workings of our bodies and compare that to other animals?  If species just popped into and out of existence, we can just hang up our coats and go home.

Of course every biology teacher has to face off against Creationists.  What surprised me in this case was how many Creationists I would have to spar with.  One of my very own colleagues was a creationist! First off, I do not back off from scientific fact.  There is no “It’s not my place to present information that challenges people’s beliefs.”  That’s not science.  My job is to teach science, as it is, and to teach kids that they can cultivate within themselves a scientific mindset that is valuable for their everyday lives.  Knowing things about science is just plain beneficial.

The writer is Sujigu, otherwise unnamed. However, the story is familiar. Answers in Genesis is a creationist group adhering to biblical in-errancy, particularly in matters relating to science, with special emphasis on biological evolution. The group is headed by Australian creationist Ken Ham. AiG has in the past few years inaugurated a creation museum (theme park) in Petersburg, Kentucky. The following is from the AiG site:

As a creationist student, you may have opportunities to share about biblical creation. After discerning the appropriatetime to speak, how can you persuade someone who has bought into the lie of evolution? Whether writing a creationist paper, giving a speech, or sharing in conversations with other students, employ the following three essential tools of persuasion…

Young Earth creationists (YEC) are not the only groups interested in coaching students to challenge modern science in public school classes. Intelligent Design creationists, such as those at Discovery Institute devote much effort to grooming public school student activists. The following is from a page on the Discovery Institute site titled “Preparing Students to Intelligently Question Darwin this Fall.” It’s by Casey Luskin, a lawyer on the Discovery Institute staff and was originally posted in October 2009, curiously under “The Church Report:”

Tip #2: Think for yourself, think critically, and question assumptions.

Though my professors rarely (if ever) would acknowledge it, I quickly discovered in college that nearly all evolutionary claims are based upon assumptions. Modern evolutionary theory is assumed to be true, and then the data is interpreted based upon Darwinian assumptions. The challenge for the truth-seeking student is to separate the raw data from the assumptions that guide interpretation of the data.

Beware circular evolutionary reasoning.  Very quickly, evolutionary assumptions become “facts,” and future data must be assembled in order to be consistent with those “facts.”

Realize that evolutionary thinking often employs contradictory logic and inconsistent methodologies. The logic employed to infer evolution in situation A may be precisely the exact opposite of the logic used to infer evolution in situation B. For example:

• Biological similarity between two species implies inheritance from a common ancestor (i.e. vertical common descent) except for when it doesn’t (and then they appeal to processes like “convergent evolution” or “horizontal gene transfer”).
• Neo-Darwinism predicts transitional forms may be found, but when they’re not found, that just shows that the transitions took place too rapidly and in populations too small to (statistically speaking) become fossilized.
• Evolutionary genetics predicts the genome will be full of useless junk DNA, except for when we discover function for such “junk” DNA. Then evolution predicts that cells would never retain useless junk DNA in the first place.

Finally, students must be careful to always think independently. Everyone wants to be “scientifically literate,” but the Darwin lobby pressures people by redefining “scientific literacy” to mean “acceptance of evolution” rather than “an independent mind who understands science and forms its own informed opinions.” Evolutionary thinking banks on you letting down your guard and letting its assumptions slip into your thought processes. This is why it’s vital to think for yourself, and identify and question assumptions.

I note in this example the writer is leading the reader, and eventually the student, down a path. In the first bullet point, for example, “Biological similarity between two species implies inheritance from a common ancestor (i.e. vertical common descent) except for when it doesn’t…” Contrary to the point that lawyer Luskin wants to make, biologists do not hang “common ancestor” completely on biological similarity.

Biological similarity is a good starting point—domesticated dogs look a lot like wolves, giving the idea of common ancestry. Also dogs and cats have fur and four legs, giving the idea of common ancestry. Both of these ideas turned out to be true. However, the so-called Tasmanian wolf (thylacine) has features resembling those of Canidae, but the two are are not closely related. The thylacine is a marsupial, while Canidae are placental mammals.

Here is an illustration from the creationist text Of Pandas and People. This appears on page 117 of the revised second edition. I have added the caption as it appears in the book.

PandasConvergentEvolution

Figure 5-2. The skulls of a dog (A), a North American wolf (B), and a Tasmanian wolf (C). Notice that the skull of the North America n wolf is somewhat similar to the dog’s, which is said to be related to it, but nearly identical to the Tasmanian wolf, which is allegedly only distantly related to it.

Notice the wording of the caption. The Tasmanian wolf is “allegedly” only distantly related to the wolf. I seldom see the word “allegedly” used so generously. The thylacine is not only “allegedly” distantly related to the wolf, it is slam dunk distantly related to the wolf. The text from page 217 elaborates and expands:

Figure 5-2 shows the skull of a dog next to that of a Tasmanian “wolf” and a North American wolf Tasmania is a large island adjacent to Australia that, like Australia, contains a large variety of marsupials. The Tasmanian “wolf” is a marsupial which in general appearance and behavior is very similar to the placental wolves found in other parts of the world. Even the behavior of this now extinct animal was similar. The Tasmanian wolves ate the settlers’ livestock, and as a result were hunted until they became extinct. But although they behaved like placental wolves, a study of their anatomy suggests that Tasmanian wolves were actually more similar to kangaroos. Darwinists interpret the anatomical findings to indicate that the two types of wolves are only remotely related, and that each had a separate evolutionary history since the time when the Australian continent was separated from the continent of Antarctica. Yet the skulls of the two wolves are extremely similar, as you see. How did this come about?

According to Darwinists, both groups evolved into wolflike forms, an occurrence known as convergent evolution. This is a form of coincidence; it means that two lines of descent took different evolutionary paths that finally converged, having independently developed similar features adapted to meet the same environmental demands. Apparently the selective regime that produced the North American wolf was established by niches closely approximated in Australia, so that the two approached this ideal ever more closely with the passage of time, increasingly coming to resemble one another until they became superficially almost identical. As time passed, Darwinian evolution, through chance experimentation, had independently developed the same general forms in two different areas of the world. Examination of the two wolves’ skulls would lead us to wonder just which features were homologous and which were analogous.

Fortunately the text does not contain any of the “allegedly” hype. In fact, the text closely resembles how a working scientist would explain the relationship between Canidae and the thylacine. Authors Percival Davis and Dean Kenyon make much use of the word “Darwinists” when they really mean “biologists.” But what of the drawings?

When the Pandas book came out a number of concerned scientists analyzed it and found it factually lacking. Frank Sonleitner was one, and his “What’s Wrong with Pandas?” document uses more print space than the original book. Here is his analysis of Pandas‘ Figure 5-2:

In the caption to Pandas‘ Figure 5-2, it is claimed that the wolf skull is nearly identical to that of the Tasmanian wolf and much less similar to that of the dog. The accompanying text claims that the two wolves are “superficially almost identical.” Actually, by looking carefully at the drawings of the three skulls, it is obvious that the dog and wolf share more specific features that the wolf and the Tasmanian wolf. One of the convergent similarities of the two forms is the carnassial teeth, the broad blade-like teeth in the upper and lower jaws that acts like scissors to slice flesh. In the wolf and dog (as in all placental carnivores) it is the last upper premolar and the first lower molar that are so modified. The other molars are reduced in size and act as crushing teeth. In contrast it is the last four molar teeth in both jaws of the Tasmanian wolf that are modified as carnassials. Clearly the carnassials of placental carnivores and the Tasmanian wolf are not homologous. In addition, the skull of the Tasmanian wolf has four molars (placentals never have more than three), only three premolars (placentals have up to four), holes in the palate, posteriorly expanded nasal bones, an alisphenoid tympanic wing flooring the middle ear, the involvement of the jugal at the edge of the glenoid fossa for articulation of the lower jaw, broad extension of the lachrymal bone onto the face of the skull and mesially enlarged angular process of the dentary (lower jaw), features which it shares with most other marsupials (Archer, 1984). In addition, the teeth appear to be homologous to the placental milk teeth; the only marsupial tooth that is replaced in life is the third premolar. Taking all these characters together, anyone can easily distinguish between the skulls of a wolf and thylacine (Figure 5.1). Denton’s claim (Denton, 1986, p. 178) that only a skilled zoologist can distinguish them is nonsense.

The “Denton” mentioned by Sonleitner is Michael Denton, author of an early “doubting Darwin” book,  Evolution: A Theory in Crisis.

Wikipedia’s discussion of thylacine uses one of the images also cited by Sonleitner:

The skulls of the thylacine (left) and the Timber Wolf, Canis lupus, are quite similar, although the species are only distantly related. Studies show the skull shape of the Red Fox, Vulpes vulpes, is even closer to that of the thylacine.

The skulls of the thylacine (left) and the Timber Wolf, Canis lupus, are quite similar, although the species are only distantly related. Studies show the skull shape of the Red Fox, Vulpes vulpes, is even closer to that of the thylacine.

Jonathan Wells is a seminarian turned biology student. He has a Ph.D. in molecular and cellular biology from the University of California at Berkeley. He is also a fellow at the Discovery Institute, and he has written a book Icons of Evolution, indicating ten faulty ideas about biological evolution. A Web site advises students on “Ten questions you should ask your biology teacher.” Here is a sample:

1. ORIGIN OF LIFE. Why do textbooks claim that the 1953 Miller-Urey experiment shows how life’s building blocks may have formed on the early Earth — when conditions on the early Earth were probably nothing like those used in the experiment, and the origin of life remains a mystery?

The hope is students will respond to a teacher’s presentation of biological evolution with questions the teacher is not prepared to answer.

This has been just a brief discussion of coaching by creationists of students. Quite often high school teachers do not have the training and the experience to answer such questions, and the creationist student is able to score points for his religious beliefs.

That is apparently the case with the middle-school teacher cited above. Here’s what happened:

So, we started talking about human evolution and natural selection.  I showed the standard pictures of Austrolopethicus Afarensis, Lucy, Homo Habilis, etc. etc. and explained human ancestry.  One of the creationists in my class looked a a photo I was showing, and then gleefully raised his hand to say that there was a “missing link” between the forms.  My diagram was purposefully incomplete because I didn’t want to include every single transitional form.  Remember, 7th graders, not people with the greatest attention spans.  I let him go to the front of the class, handed him my marker, and let him happily point to where he thought there was a gap.  “If this is a monkey and this is a monkey, then where’s the link between this and a human?”  I then asked him a question…

“What gap?”

“This one, this one right here!  You need something here.”

“No I don’t.”

“Yes you do, you need something here.”

“Why?”

“Because if you don’t have it then this doesn’t make sense.”

The kid was dumbfounded by the fact I just wasn’t impressed.  He laughed and was excited.  His father is a pastor, so I know that his father passed this idiocy onto him, and he was making dad proud.  It was kind of sick in a way.  I then rolled up the overhead projector, and did a quick sketch of a jigsaw puzzle.

Students in the class agreed this was a jigsaw puzzle. The teacher pointed out this was not a puzzle, according to the logic of the creationist student. That was because there were missing pieces. Another student pointed out that missing pieces are allowed. It’s just necessary to find them and to complete the puzzle. The creationist had no response for this argument. His coaches, who were not really scientists but theologians did not comprehend how science works. Generally scientific research can never be considered complete, because we can never be assured we have found all the pieces.

I will add my own part. Suppose I have evacuated a huge aircraft hanger and swept clean it’s acre of concrete floor space. I have a few pieces of an enormous jigsaw puzzle, and I have started putting the pieces together. I have fitted a number of the pieces, and something of the image is beginning to show. However, 99% of the floor space is still vacant. Besides, I still have a pile of pieces that have not been fitted, and even if they were fitted the puzzle would be no way nearly complete.

An onlooker is challenging me. “You don’t have all the pieces, but you still insist on telling me a coherent picture is going to come out of this. What makes you sure your partial picture is correct?”

My answer would be, “All pieces I have successfully fit together agree with the expected picture. Also, I have been putting pieces together for 200 years, and I have never found a piece that is not part of the picture.”

And that’s the way it is with modern biology. In all of human history we have never found evidence that contradicts biological evolution by natural selection. We have never found a piece that does not fit into the puzzle.

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