Filed under: Science
Original Post (with comments)
There are far too many people who approach evolution as a theory which opposes most religious creation myths. So I have no choice but to spend some time on the evolution versus creationism debate. There are large books dedicated to making a case for creation science – as if it could ever be considered scientific. Rather than make this a treatise on the evolution versus creationism debate, I’ll stick to the best (yet startlingly inadequate) of the creationists’ arguments against evolution. The first is regarding the so-called “design problem”.
The question is how could evolution by way of natural selection have created such staggering living complexity. How could it create something as complex as a human eye, for example? After all, if evolution brings about changes gradually by acting on the occasional mutation, how could something as sophisticated as a binocular eye have emerged? To answer this, consider the time when the Earth was populated with simple animals – some of them with no eyes. Of course, natural selection was around back then – always finding the fittest animals to create subsequent generations. So the issue with binocular vision is the intermediate steps. What possible value could half an eye confer upon its host? It turns out that natural selection is quite handy at using seemingly innocuous talents to an animal’s advantage.
For example, imagine a population of little slug-like animals. These animals slide along the ground eating bacteria and such. They also happen to be the favorite food of another, more sophisticated crab-like animal. These crabs hunt during the day, gobbling up slugs whenever they find them. Now imagine that one day a slug emerges with a thin patch of cells on its dorsal side. It just so happens that this set of cells is light sensitive. Before your BS detector goes off, remember that evolution has millions of years to work with. Nature randomly explores the range of mutations quite well over that kind of time.
So the imaginary slug has light sensitive cells. When the slug is exposed to sunlight, these cells contract causing the slug to move away from the light. Now selection goes to work. Since the slug’s mortal enemy is the crab and the crab only hunts during the day, the mutated slug will enjoy a reproductive advantage over its contemporaries. During the day, while they’re randomly sliding around looking for bacteria, the mutant stays put in a shady hiding spot. The crabs pick off the others while the mutant is safe. It is easy to see how the mutant would live to make baby slugs. Over time, the population of slugs would be filled with light-sensitive individuals. Now imagine that a new predator comes on the scene.
This lizard-like animal hunts both day and night by using scent detection. The lizard doesn’t see very well so it uses its tongue to detect scent changes in the air. Now suppose that, when a slug feeds, the chemical reactions taking place give off a specific odor. The lizard has the ability to detect this odor. When it detects the scent, it follows it to its origin and eats the slug. So what happens if a new slug mutation causes the light-sensitive patch to be able to detect motion? Those with this new mutation would be able to detect the presence of the lizard and stop feeding. Those without it would continue to feed, oblivious to the threats around them. The continued emission of the odor would attract the lizard to them and that would be that. Again, thanks to selection, this mutation would flourish in the population.
These two just-so explanations are more than plausible given the long periods of time evolution has to work with. We can invent one after another until we arrive at an animal with a very sophisticated visual system. The point is that intermediate stages of design do exist and natural selection makes handy use of them. Moreover, given the choice between an argument that defies all natural explanation and an argument that is plausible, the clear thinker will choose the latter. There really is no design problem.
With the design problem worked out, I’ll turn to the question of transition fossils. Creationists typically do not accept the above explanation of the design problem because they argue that even if the intermediate stages were useful, the fossil record does not show the transitional forms that led to the current designs. They would say that there are no fossils of early light-sensitive slugs so they must not have existed. But this is not exactly true. In fact, the fossil record shows many intermediate designs. The transitional fossils between amphibians and reptiles are so various that it is extremely difficult to tell where one begins and the other leaves off. It doesn’t help matters that the prevailing system of classification of animals is somewhat arbitrary in its assignment of type.
For example, the dinosaur Archaeopteryx is clearly an intermediate between reptiles and birds – even though reptiles and birds don’t seem that closely related when you look at today’s zoological classifications. This is simply because early taxonomists didn’t have access to the information we have today. If we were to now reconstruct animal taxonomy based upon genetic similarity, we’d end up with a whole new classification system. This would be a big change so I doubt it will ever be done. But it doesn’t really matter. Even though this situation is a bit of a thorn in our side, the facts are still the same – there are plenty of transition fossils to lend credence to selection’s role in shaping life on Earth.
Creationists also like to highlight their misunderstanding of thermodynamics in their quest to overthrow evolution. Their argument is that evolution disobeys the second law of thermodynamics. They are referring to entropy, the idea that systems tend toward disorder from order. The order and complexity of living systems, in their view, is something that could not have emerged because systems should be moving toward disorder and simplicity. But this is simply incorrect.
For one thing, the second law of thermodynamics doesn’t really deal with order and disorder. It deals with energy and how it flows in and out of systems. The second law of thermodynamics actually tells us that something complex can spontaneously emerge from something simple if the energy of the complex entity is lower than the energy of the constituents. Ice is a good example. But even if we put that aside, the second law also only deals with closed systems. An open system (meaning energy and/or matter can flow in and out of it) has no such restrictions. The creationist’s argument is like saying that a bicycle is impossible because entropy would force the components apart. But this is absurd. In this case, a bicycle is an open system. The energy applied by the mechanic to put it together is all it takes to make a bicycle from its parts. As long as living systems are open systems, the second law of thermodynamics can have no real bearing on their complexity. The inflow of energy and resources from the environment can account for any and all levels of complexity seen in living organisms.
The last major argument creationists tend to make against evolution is the silliest, in my opinion. The Bible lays out a timeline for man that is about 10,000 years long. Adam and Eve were supposedly created 10,000 or so years ago. But archaeologists have found multitudes of humanoid fossils that date back 2 million years. So creationists dispute our current dating techniques. They cite the decay of the Earth’s magnetism and the fallibility of Carbon 14 dating as evidence that the Earth is really only 10,000 years old. The reality is that the Earth’s magnetism is known to have reversed many times in its history. So it may be true that extrapolating the decay into the past indicates that the magnetism changed 10,000 years ago. But that certainly doesn’t lead to the conclusion that the world is 10,000 years old! Furthermore, Carbon 14 dating has been proven accurate countless times. This is just the kind of denial of reality that comes with trying to make facts fit theories instead of the other way around. It doesn’t work.
I’ve read several books on creationism and I have yet to run across one that puts forth an even remotely reasonable argument. As always, I’m willing to change my mind, but not based upon what’s currently out there. Anyone got anything better?
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