Strike Another “Vestigial” Organ

(Public Domain Image)

Evolutionists think there is a lot of junk in nature. Of course, that’s what you expect if you think a process that depends on random mutations acted on by natural selection is what produced all the life we see today. If you think that the world and life on it were created by God, however, you wouldn’t expect to see much junk. If you believe in the Christian God, you do expect some junk, because the Bible tells us that creation is in “slavery to corruption” as a result of the Fall of man (Romans 8:21). Thus, there has been some corruption from the supremely-designed state in which nature started. As a result, there should be some junk in nature, just not much.

One specific kind of junk that has been predicted by evolutionists over and over again is vestigial organs. These are organs that supposedly had a function in an evolutionary ancestor but have no important function in a current organism. For example, it was long thought that the primary cilium that appears on nearly every cell in the human body was vestigial. It was supposed to be a remnant of the evolutionary stage when our ancestors were free-swimming, single-celled creatures. Of course, we now know that the primary cilium serves several incredibly important functions.

More famously, it was long taught that the human appendix was vestigial. Supposedly it was a remnant of the evolutionary stage when our ancestors ate a much more vegetarian diet. Of course, we now know that this is false as well. Instead, the appendix has been shown to have an incredibly important function in people. Evolutionist Jerry Coyne made a huge blunder in his book, Why Evolution is True, because he claimed that the fine hair a human fetus grows all over its body (called “lanugo”) is vestigial. However, it has been long known that lanugo serves an incredibly important function.

As you would expect, modern science has just struck down another vestigial organ. This time, it is found in salmon, trout, and many other fishes*.

These fishes have a small “fin” between their dorsal fin and their caudal (tail) fin. It is pointed out in the picture above. I put fin in quotes because it’s not really a fin. Instead, it’s a growth of fatty tissue. In fact, it’s called the adipose fin because “adipose” means “composed of animal fat.” Evolutionists have long considered this to be a vestigial structure. As Ken Schultz’s Field Guide to Freshwater Fish says:1

Like all salmonoids, the brook trout sports a vestigial adipose fin on its back.

Not surprisingly, however, the evolutionary description of the adipose fin turns out to be dead wrong. Instead, a recent study has shown that salmon who have their adipose fin cut off must exert more energy to swim that those whose adipose fin is not cut off.2

In the study, the authors took steelhead trout and swam them at various speeds. The authors measured how quickly the fish beat their tails back and forth as well as how far the tail moved back and forth in order to produce a given speed. In other words, they measured the frequency (how quickly) of the tail’s motion as well as its amplitude (how far). They then clipped the adipose fin and made the same measurements again. Guess what? They found that the fish had to beat their tails with an 8% greater amplitude when their adipose fins were removed.

Now the authors were worried that this larger tail amplitude might just be a reaction to the pain of having the adipose fin removed. In order to test whether or not this was the case, they repeated the experiment with other fish, this time just deeply scratching the fin rather than cutting it off. This still produced a lot of pain, but it didn’t get rid of the adipose fin. In this phase of the experiment, there was no difference in tail frequency or amplitude before and after the scratch.

So the results really do seem to indicate that fish with their adipose fin removed swim less efficiently than those with their adipose fin intact. What is this fatty fin doing to help the fish swim? The authors don’t know for sure, but they have their ideas. Since it is not structured much like a fin, it is hard to believe that it produces thrust like the caudal fin does. So they looked at some of the tissue in the adipose fin to see what functional elements were there, and they found sensory nerves. Thus, they think that the adipose fin is a sensory organ.

How would that help the fish swim? According to the authors, their results:

…indicate reduced swimming efficiency following adipose fin removal across multiple flow velocities leading to a hypothesis that the adipose fin may act as a precaudal flow sensor when swimming in turbulent water. Such a flow sensor could detect the chaotic vortices before they enveloped the caudal fin providing direct feedback to the central nervous system and subsequent improved caudal fin motion during swimming.

Whether or not their explanation is correct will require a lot more study. However, I think their publication adds to the huge pile of evidence that there is little junk in nature. This, of course, is quite consistent with the creationist view of nature and quite opposed to the evolutionary view of nature.

Interestingly enough, this false evolutionary interpretation of the adipose fin has caused many fish hatcheries to clip it off of their juvenile fishes before they are released into the wild. That way, fishermen know which fish are hatchery fish and which fish are “natural” fish. To be able to legally fish on some rivers, you have to release any fishes you catch that still have their adipose fin. That way, you are only keeping the fishes that come from a hatchery. However, this research (and the creationist view of nature) says that this is a bad practice, as it puts the fishery-hatched fishes at a disadvantage. This isn’t the first time evolution-inspired ideas have led to practices that produced negative effects, and it most certainly won’t be the last.


1. Ken Schultz, Ken Schultz’s Field Guide to Freshwater Fish, Wiley 2003, p. 228
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2. J. A. Buckland-Nicks, M. Gillis, and T. E. Reimchen, “Neural network detected in a presumed vestigial trait: ultrastructure of the salmonid adipose fin,” Proceedings of the Royal Society B, doi: 10.1098/rspb.2011.1009, 2011
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* In case you are wondering, “fishes” is the proper term to use if you are talking about multiple species of fish. If you are only talking about one species of fish, then “fish” is the plural. So an aquarium with a goldfish and a guppy has two fishes in it, while an aquarium with two goldfish has two fish in it.
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7 thoughts on “Strike Another “Vestigial” Organ”

  1. Wow! Thanks for that post Dr. Wile! I’m always disappointed when I see someone says that “this must be left over from the last species” or something equally dogmatic.
    P.S. I loved your book on biology.

    1. Thank you so much, Isaac. I am thrilled that you enjoyed the biology book! I personally think that when an evolutionist says, “this must be left over from evolution,” he or she is hindering science, because the statement causes people to stop looking for a function. It is much more productive to approach science from a creationist standpoint, which assumes that almost everything in an organism is functional.

  2. Very interesting Dr Wile! I just read several reviews on Jerry Coyne’s book so it was especially timely. ANd I remember being taught that the appendix was vestigial and don’t know that I ever learned otherwise until now!!

    I had been digging through your blog a little and found some stuff on quantum mechanics. I am just learning about this and it is beyond my understanding in many ways, but is it at all noteworthy that although it is not possible predict the exact behavior of the individual atomic particles in space with respect to location; when considered collectively, their behavior *does* correspond to a predictable *pattern* ie, wave function?

    If this is a fair statement (maybe it’s not – I don’t know), then should it be very bothersome that we cannot predict the behavior of a particular electron with 100% certainty? Just wondering if you could educate me a little. Thanks!

    1. Thanks, Elizabeth. It is amazing how many incorrect things we are taught about science!

      Your statement is fair. While we cannot pinpoint the precise location AND momentum of a particle, its behavior is governed by a wave function, which is predictable. Essentially, the wave function gives us a range of probabilities for the location of a particle. We can’t say “it will be here in the next minute.” However, we can say, “There is a x% probability that it will be here in the next minute, and a y% probability that it will be here the minute after that.

      To me, this is not bothersome at all. As a matter of fact, I find it reassuring that there is no precise ability to predict what will happen next. If the universe worked by Newton’s mechanics, then if we knew ALL the initial conditions and ALL the variables, we could precisely say what will happen in the future. In such a universe, I don’t see where there is room for free will. The fact that the universe seems to work by probability rather than certainty leaves room for the concept of free will.

  3. “The fact that the universe seems to work by probability rather than certainty leaves room for the concept of free will”… I was kind of thinking along those lines!

    And also, the fact that although the behavior of the particles is not “predictable” (man’s free will), the range of possibilities is governed by the wave function–like God being ultimately “in charge” of the universe/history as the Bible says in Isaiah 46:10 “I make known the end from the beginning, from ancient times, what is still to come. I say: My purpose will stand, and I will do all that I please”

    That’s rather satisfying to me! It’s amazing how much “the Creation” (science) reveals about God – His glory, character and intelligence… Psalms 19, Romans 1:20, etc, etc… Pretty Fascinating!!

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