The Appendix/Cave Fish Eyes/Etc. are (NOT) vestigial

(Ashwin S) #21

Except that we see the same genes involved in the same function in unrelated organisms… people call it convergent evolution, parallel evolution etc.

There are papers which say the appendix came and went 32 times in mammals… and it’s not only the appendix.
The eye seems to have evolved several times. Though some instances are that of different mechanisms creating similar result, some are homologous genes/biomolecules etc.

On the other hand we have things like hair/fur in mammals which remain constant through 100’s of millions of years… even though there are close alternatives like scales, feathers etc which could have arisen, considering the diversity achieved by this group.

Considering that species change by both dropping as well as gaining traits, it’s very difficult to see how some specific traits remain conserved for immense durations while others don’t (and it’s this consistent conservation across time involving immense change in other genes which creates nested heirarchies)… and even these traits are not common throughout life… they vary from class to class…

Edit: one example for a naturally occurring nested heirarxhy in biologicals systems is embryo development. It leads to cells that occupy a specific niche in the body through a process involving heavily regulated/controlled variation. That’s the only way to get a nested heirarchy. Control over the process of change.

(A.M. Wolfe) #22

When they believed Pluto was a planet, they found this supported the basic tenets of modern astronomy. When they found that Pluto was not actually a planet but a dwarf planet or possibly even a collection of gazillions of comets, they found that this still supported the basic tenets of modern astronomy! This shows a disturbing difficulty to actually falsify the basic tenets of modern astronomy in any way.

Said no one ever.

(P.S. Yes, I know that vestigial organs play a somewhat larger role in the historical development of evolutionary theory than that of Pluto in modern astronomy. My points still hold that [1] the argument from vestigial organs is just one very small piece of an enormously complex network of evidence that all supports common descent with modification / evolution, and [2] disproving one example (one vestigial organ) does not disprove the entire element of the theory (all vestigial organs).)

(A.M. Wolfe) #23

…and calling the human appendix vestigial isn’t?

(Ashwin S) #24

It isn’t a classification issue.
Vestigial used to denote an organ that lost its function as a lineage progressed. Darwin used to use it as an argument against design.
Thus, if we saw, an organ without a function down the line in a tree, and it had a function when we go back in time, it is vestigial. (This makes sense to me).

Later when function started being identified for vestigial organs, the definition was changed to include organs that lost its initial function and gained a new one.
By this definition, everything that evolved a new function is vestigial.
For example, the forelimbs of four legged animals are supposed to have evolved into fore arms in primates and the function changed from helping in walking/running to helping in climbing/ handling tools in the case of humans…
By the new classification, arms should be vestigial. And pretty much anything that evolved a new form/function becomes vestigial.
This makes the application of this classification whimsical.
The appendix is vestigial… fore arms or wings are not.
Leading to tautologies… And unfalsifiability.
It’s dissatisfactory.

(A.M. Wolfe) #25

Hi George,

Honestly, I would actually be interested to hear others’ (e.g., @T_Aquaticus’s) responses to Ashwin’s final comments on vestigial organs before I reprise this argument for you. Why is an arm not a vestigial fin, etc.? His particular argument about the human appendix seemed to me to be a paltry classification issue, like Pluto’s planetary status, not capable of falsifying anything at a broader scale — but as he widened his comments to include the definition of vestigial limbs in general, I thought, well, this deserves a response from someone more qualified than I. Vestigial organs are just one small support among the many, many converging streams of evidence for common descent with modification; nevertheless, to the extent that vestigial organs remain a convincing support for evolutionary theory in the popular mind, if the meaning of the term has become so vague as to be synonymous with “exaptation,” why don’t we just talk about exaptation?

(Ashwin S) #26

The appendix is not the vestige of the cecum.

@AMWolfe- even after studies prove that the Appendix is a seperate organ from the cecum. We find such claims…
I have no idea why.

Above is a paper that deals with this issue in detail.

(Phil) #27

The paper does suggest that the widespread presence of the appendix in multiple species is indicative of common descent from an ancestor who had one, though its usefullness waxed and waned

(Ashwin S) #28

Approx 32 times…
Anyway, I was just pointing out that it’s a little ridiculous to continue calling the appendix vestigial …
Even if you accept it’s not vestigial, I am not going to point to that piece of fact and say evolution didn’t happen…

Edit: waxed and waned is not the word… appeared and disappeared… no evidence of slowly becoming useless and disappearing.


The appendix does not help humans digest cellulose. That is why it is considered to be vestigial.

(George Brooks) #30

@pevaquark & @T_aquaticus & @jpm :

I don’t believe anyone gets anywhere disputing Vestigial anything. Too much room for problems with terminology and so forth.

Letting vestigial topics dominate the discussion is like letting the Koch Brothers dominate a conversation on Global Warming by discussing how clean their coal is.

The topics (whether it be clean coal, or vestigial organs, or % Chimp DNA - - though endless interesting - - are not low-hanging fruit in regards to the main issue of defending and educating Evolutionary principles.

Creating Information Naturally, Part 1: Snowflakes, Chess, and DNA

Vestigial does not mean useless.

Creating Information Naturally, Part 1: Snowflakes, Chess, and DNA

In a paper referenced by the paper @Ashwin_s linked above it does indicate that the appendix has appeared 38 times and been lost 6 times. An interesting paper by the way.

The Cecal Appendix: One More Immune Component With a Function Disturbed By Post‐Industrial Culture

And from the Conclusion

So even if Darwin got it wrong in general (he was only aware of the appendix in humans) it still supports evolution as the appendix appears as needed.

Yes @Ashwin_s I know you will argue that this just means evolution is not falsifiable. I prefer to think that the theory of evolution is robust enough to account for new data.

Creating Information Naturally, Part 1: Snowflakes, Chess, and DNA
(Phil) #33

Why do you think it disappeared? Not a whole lot of fossil appendixes (?) around. Are you saying it independently evolved 32 times? References?

Creating Information Naturally, Part 1: Snowflakes, Chess, and DNA
The Appendix/Cave Fish Eyes/Etc. are (NOT) vestigial
(T J Runyon) #34

You aren’t taking into account the history of the theory. I agree there isn’t much that could disprove the theory, TODAY. That’s a sign of strength. 150 years ago? There was tons! But an overwhelming amount of evidence gathered since then have come to the same conclusion. Common ancestry. The odds are of so many disciplines coming to the same conclusion just by coincidence is extremely low. we aren’t going to throw out a crazy successful theory because of a few anomalies. No theory in the history of science has EVER agreed with every empirical observation. The fact that evolutionary theory can accomodate new and unexpected data so well is because it’s been so successful in explaining a wide range of data. Also, I’m not sure the human appendix is vestigial either due to the number of times its evolved independently but it’s something I haven’t put much time into thinking about. Finally, vestigial is defined independently of evolutionary theory. A vestigial trait is a reduced and rudimentary structure compared to the same structure in other organisms. If functional, they perform relatively simple, minor, or inessential functions using structures that were clearly designed for another purpose

Creating Information Naturally, Part 1: Snowflakes, Chess, and DNA
(Ashwin S) #35

The paper I cited claims that…

. The appendix has evolved minimally 32 times, but was lost fewer than seven times, indicating that it either has a positive fitness value or is closely associated with another character that does. These results, together with immunological and medical evidence, refute some of Darwin’s hypotheses and suggest that the appendix is adaptive but has not evolved as a response to any particular dietary or social factor evaluated here.

(Ashwin S) #36

Right now, I am just glad someone is willing to admit the appendix is non vestigial. :slight_smile:

Frankly, I find it hard to believe the appendix evolved 38 or 32 times (maybe @jpm does too). … It just means that the appendix is found in places where it should not be (according to CA) around 30+ times… and is assumed to have emerged on its own.
If you want to see that as a strength, it’s your choice.

(Ashwin S) #37


Neither does the brain (digest cellulose)… is it vestigial.

We can’t insist an organ have the function we want it to have… there is no evidence the appendix had anything to download digesting cellulose… if the paper I cited is true… it’s the contrary. It had nothing to do with it.

(Matthew Pevarnik) #38

You’ve made this false equivalency here and seem to be making up arbitrary definitions of what vestigiality means apart from any scientific definitions.

Same argument from a few days ago that again seems to be based off of a fundamental misunderstanding of what the word even means:


The appendix, as part of the caecum, does help digest cellulose in other species.


No. If you read the Laurin paper it appears to have evolved twice and it only appears in those descendants. I think of it as evolution finding a tool which it then uses only when necessary. It appears when conditions render the presence of the appendix an advantage and disappears when it is no longer an advantage.