As noted in Part I of this brief series, The Evolving Nature of Evolution: "Properly Taught", the American Geophysical Union made the following statement in response to President Bush's comments of three years ago that both sides of the Darwinian Evolution v. Intelligent Design debate ought to be properly taught" so that "people can understand what the debate is about":
"Scientific theories, like evolution, relativity and plate tectonics, are based on hypotheses that have survived extensive testing and repeated verification," Spilhaus says. "The President has unfortunately confused the difference between science and belief. It is essential that students understand that a scientific theory is not a belief, hunch, or untested hypothesis."
With respect to the statement that "Scientific theories, like evolution, relativity and plate tectonics, are based on hypotheses that have survived extensive testing and repeated verification," I would really like someone to explain exactly what "testing and repeated verifications" Darwinian evolution has undergone.
Let me be clear here: I am not saying that there is no evidence that evolution occurs. Certainly, one can look at the fossils that led to the drawings which appear to demonstrate that the horse evolved and reasonably conclude that the horse did, in fact, evolve. We can look at finches beaks (as Darwin did) and reasonably conclude that there have been adaptations. We can look at micro-organisms and their propensity to change from generation to generation in response to the conditions of their environments as further evidence of evolution. But what about the central claim of Darwinian evolution: that all life evolved from single-celled organisms into the vast diversity of life that exists today? Where exactly has that been tested?
In researching testing of evolutionary hypotheses, I came across an article by Dr. Leon Higley that was originally posted on the University of Nebraska Lincoln website (which has now been partially preserved on the Marine Insects Homepage for the University of Nebraska Kearney) discussing the testing of the evolutionary hypothesis by asking why insects haven't succeeded as well in water as on land. While being a strongly pro-evolution paper, it made several points that I found very interesting. Here's what Dr. Higley said (emphasis added):
A scientific hypothesis is an explanation that’s a guess. The value of any hypothesis is how well it accounts for what we know to be true. There’s nothing wrong with wild hypotheses, but their longevity depends on how well they stand up to facts. If they don’t fit the facts, they die (as they should).
Testing hypotheses is big business for scientists. When you do experiments, where you (at least in principle) control every factor except the one you are examining, hypothesis testing usually involves using statistics. Statistics are important, because they provide a mathematical statement based on probability theory of how likely a given outcome is. By convention, scientists tend to say that unless an experimental result could have occur [sic] only 1 time in 20 (5% of the time), it probably is not a real effect.
Unfortunately, given that we don’t have planets and hundreds of million of years to experiment with, we have to take a different tack with the marine insects question. Here, as in much evolutionary argumentation, we try to form plausible hypotheses, and then try to find evidence that supports or disproves these guesses. Once a hypothesis is formed, we look for current examples that would contradict it. For example, the argument that insects can’t survive in the ocean because of water pressure doesn’t seem so good when you realize one insect species survives at a depth of 1,300 meters! This is a form of counter example. Because at least one species can survive a great depth, it implies that other insects could have evolved to do so. Eliminating hypotheses by counter examples is a powerful approach in assessing hypotheses.
Counter examples are a type of comparison (comparing one species’ biology with what might be possible for the group). Often comparison provides a mechanism for supporting a hypothesis. In our marine insects example, we compare insects in the oceans with insects in fresh water. We find that lots of insect species live in fresh water, but almost none do in the oceans. Compare: what is different about the two habitats? If it isn’t something physical (such as salinity or water pressure), maybe it has to do with biology. There are lots of small crustaceans in the ocean, but not so many in fresh water. OK, maybe the crustaceans beat out the insects. Is there any other evidence? Well, the fossil record shows that the crustaceans appeared many millions of years before insects. Like shopping for Tickle-Me Elmo (or whatever is the current faddish toy), those who get there first, win. And, if the crustaceans are out-competing insects, this fits with another theory (a type of strong hypothesis), the competitive exclusion principal. [sic] (Competitive exclusion is an ecological theory that two species can’t both have identical ways of making a living [occupy identical niches], because one will inevitably displace the other.) Competitive exclusion really isn’t evidence for or against our competition hypothesis with marine insects, but it does show our hypothesis doesn’t contradict a widely held principal, which is good. Does any of this prove competition with crustaceans is the reason for the lack of marine insects? Not really, but (to us) it is the best explanation to fit all the available facts.
This last point is very important. Theories are really hypotheses that have stood the test of close examination and time. It is possible to disprove theories, but in most instances it is not logically possible to prove a scientific theory. We can get close, but that is not the same as certainty. Consequently, the (ignorant) argument that something (like evolution) is "only a theory," ignores how the entire business of science works.[sic]
One other way we can test hypotheses is by making predictions. This is harder with evolutionary questions, because typically we can’t look at evolutionary processes over the long term. However, we might design small experiments where we look at competition among fresh water crustaceans and aquatic insects, and in these experiments we can predict how competition should produce different results. Again, such experiments wouldn’t prove or disprove our hypothesis, but they might support aspects of it or cause us to modify our ideas. In a nutshell, that’s science.
I personally find Dr. Higley's article to be informative in several respects, but more interesting in what it shows about the nature of research into evolutionary science. First, it notes that evolution has not been directly scientifically confirmed by testing -- and we shouldn't expect that it ever can be. Rather, when dealing with evolution, scientists try to find "evidence that supports or disproves" the "plausible hypothesis." Keep in mind that the plausible hypothesis is itself simply a reasonable "guess" (Dr. Higley's word) about what happened in the distant past that led to the state of nature that we find. In other words, evolution is simply a framework or model which scientists posit to explain what is observed.
Does the fact that Darwinian evolution is not directly testable mean that the evolutionary theory is necessarily wrong? Of course not. As Dr. Higley points out, science has observed many things that correspond with what one would expect if evolution were, in fact, true. These consistencies do bolster the case that evolution is more than the means adopted by atheists to make them intellectually fulfilled (using the words of the bombastic Richard Dawkins).
But what about when the evidence doesn't fit the theory? In many cases, the evidence we find is inconsistent with what we would expect if the evolutionary framework were true, like finding that although insects evolved and have been highly successful on land, they have been entirely less successful in water for no apparent reason. In fact, the reason most commonly given (that they don't survive in high water pressure) has been demonstrably shown to be false -- as noted by Dr. Higley. So, when something doesn't fit as predicted by evolutionary theory, does it disprove evolution? No. Rather, it simply means that scientists need to adapt the framework to fit the new data. In Dr. Higley's case, it means adopting a different idea of "first arriving wins" to the competition between crustaceans and insects. Never mind that "first arriving wins" doesn't seem to actually be the rule in nature as demonstrated, using one example, by the fact that Africanized honeybees are apparently displacing the earlier arrived domestic honeybees as they move northward from South America.
Let me say once again that this in no way shows that Dr. Higley is ultimately wrong. He may be absolutely right that evolution occurred and the fact that crustaceans arrived first is the reason that they have been more successful in salt water environments than the later arriving insects. But Dr. Higley's example also shows that Darwinian evolution is like Jell-O -- infinitely malleable. The theory itself is evolving much more quickly than the animals it contends evolved, and trying to demonstrate that the underlying theory is wrong is like nailing Jell-O to the wall because it will simply change shape to move away from the nail.
In Darwinian evolution, if the evidence doesn't support the theory, the theory simply changes to adapt to the new information. Scientists, wedded to the pre-conceived but unproven notion that evolution is true, conclude that such inconsistencies merely mean that some of the details of the theory were not necessarily accurate while the underlying theory remains untarnished. But this evolving nature makes it impossible to actually test the theory using the examples and counter-examples cited by Dr. Higley. After all, these examples and counter-examples only affect parts or details of the overriding theory which has not and cannot ever be tested.
Next time: Two analogies