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


(Randy) #61

Oh gross…you’re right of course. Sorry. Thanks. Now I look at it, BBC has a whole interesting discussion about how it may have allowed us to adapt to the plains and hunting. Thanks for the correction @jpm too. http://www.bbc.com/earth/story/20160801-our-weird-lack-of-hair-may-be-the-key-to-our-success


#62

Loss of body hair could be to aid in cooling when we were running down game in Africa. Hairiness makes it more difficult for ticks to latch on, so they favor the ears in dogs. But hair is also a good hiding place for ticks. In Texas we used to laugh about “rude ticks.”


#63

actually both body hair and coccyx have functions:


(Randy) #64

@beaglelady and @jp. That is the paper I had in mind earlier…was on bbc but I thought I must have imagined it as I could not find it. Thanks @outrigger @jpm
Function of just about anything is expected.


(Curtis Henderson) #65

@outrigger, you are missing one of the main points of this entire thread. Vestigial does not mean “no function at all”, vestigial means “reduced function compared to ancestral versions”. Check here for a definition in a biological dictionary.


(Phil) #66

Thanks! Interesting article, though being part of the study would be …interesting. I remember one trip when I noticed blood on the sheets one morning and wondered what was up with that, only to find the offending bedbug bites a little while later.


(Randy) #67

Rather a scary thought, I agree. I think that’s how some of my patients wind up getting bed bugs. They visit some fancy hotel, and don’t realize they picked up a visitor.


#68

I.HATE.BEDBUGS


#69

@outrigger:

human body hair has reduced function. And what about Arrector Pili: The muscle fibers that give you “goose bumps.” Do they fluff up your fur to keep you warm, or make your hackles rise to scare off evolution folks?
(With our bipedal stance, nobody would see our hackles anyway.)


#70

Anal glands in dogs are vestigial. According to vets they serve no purpose. And they get impacted and stink like hell.

And dew claws on species such as dogs, goats and cows are vestigial. And the splint bones in horses are vestiges of when horses had multiple toes.


(Randy) #71

I believe they are vestigial, but most of the time if our bodies maintain them there seems to be some purpose. For example wouldn’t they go away entirely if there was no use at all? I have never had a dog but one site says the anal glands mark territory. And arrector pili muscles help close your pores when it’s cold…I used to hear that that helps us a little. The Hardy Boys mystery stories seemed never to complete a tale without Frank and Joe feeling the hair prickling on the back of their necks…so that’s adaptive for mystery stories, because it tells the protagonists that they are around danger (kidding). Anyway, the maintenance of function just seems to mean that evolution is very economical. :wink:


(Matthew Pevarnik) #72

@cwhenderson already helped clarify what it means to be vestigial.

Here’s a thread from earlier this year beginning with an excellent explanation from @T_aquaticus:


#73

Dogs use urine to mark territory. Sometimes they empty their anal glands when they’re frightened. If they used anal gland to mark territory, walking with them would stink to high heaven. Skunks can discharge anal glands at will, and that really stinks also.

Haven’t heard that one!


(Chris Falter) #74

@outrigger
@Ashwin_s

If you were a specimen of A. mexicanus swimming in a cave, you would not be able to read this comment because your eyes would be under a flap of skin and completely nonfunctional (et alia).

Do you think the eyes of A. mexicanus are vestigial?

Thanks,
Chris


(Ashwin S) #75

The reason i asked was that the paper i cited does not link the emergence of the appendix to change in diet…
So, I doubt its main function is to help in digesting cellulose.

Nowadays the socket to fix a charger for mobiles/tabs etc… Its become far more important… So perhaps its an exaptation. :slight_smile:

No idea chris. But knowing something is vestigial would require one to identify its direct ancestor… and then identify function (in this case for the eye).
An approach in which, we categorise every organ whose function we don’t know as vestigial wouldn’t be appropriate.
Not knowing an organs function doesn’t make it vestigial (it just shows we dont know).
We need to establish the following-

  1. Presence of the organ in a common ancestor.
  2. Its function when it first appeared.
  3. Proof of reduced function (No exaptation. In which case, pretty much everything is vestigial)
    I personally believe there is some amount of plasticity/programmed alternatives in the genome which help organims adapt to different situations over generations. This means organs/traits can be lost and found as required.
    However, the problem for evolution is to describe how “lost” traits such as the appendix are found again by “chance”.
    I am attaching an interesting study of the blind cave fish.
    https://www.sciencedirect.com/science/article/pii/S0960982207022622
    @beaglelady, @Randy, @Bill_II

@pevaquark:
Thanks for sharing the paper. There seems to be no change in their conclusion. Can you make your point clearer? In fact, they have revised the earlier estimate of 32 to 29-41… That is an average of 35. So, they are underlining their claim that the appendix evolved many times.

Blockquote
This expanded dataset reveals that the cecal appendix has evolved a minimum of 29 times, possibly as many as 41 times, throughout mammalian evolution, while it has only been lost a maximum of 12 times. This statistically strong evidence that the appearance of the appendix is significantly more probable than its loss suggests a selective value for this structure. Thus, we can confidently reject the hypothesis that the appendix is a vestigial structure with little adaptive value or function among mammals.
Blockquote

The authors don’t think the reduced no: of appearances in Stepsirhini clade will change their overall conclusion that the appendix appeared many times. I will quote what they wrote which is abundantly clear.

Blockquote
The minimal number of gains (29) is lower than in our previous study (32, in Smith et al., 2013), despite the addition of several taxa. This results mostly from changes in
topology, which, in some cases, yields ambiguous optimization where, in our previous study, several appearances of the appendix had been hypothesized. The strepsirhines
illustrate this. The reference tree of our previous study implied five gains ofthe appendix in strepsirhines (Fig. 3A), at least under some resolutions compatible with the polytomy.
The updated tree, with two additional strepsirhine species (26 instead of 24; we added Nycticebus pygmaeus and Mirza zaza) implies at least one gain only, because the
optimization at the root of Strepsirhini is now ambiguous (Fig. 3B). Note that in both cases, as many as eight gains are compatible with one of the most parsimonious optimizations.
However, note that as expected, the increased amount of data and greater resolution of our tree result in a greater number of evolutionary events. Smith et al. (2013)
had identified 38 events (including 32 to 38 gains), whereas we have now identified 41 events (including 29 to 41 gains)*.
Blockquote

To be frank, i don’t agree with their conclusion. I just think the “evolutionary tree” is wrong… and this is the result of forcing an imaginary construct on reality. You get a weird distorted view.
They should have questioned their assumption of common ancestry… which they did not.


#76

@Ashwin_s An “imaginary construct” that works extremely well.

I don’t remember if I asked you this question before but I will repeat myself.

If evolution is fundamentally wrong then how can paleontologists successfully use it to find fossils of an unknown creature?

The question of the origin of the appendix wouldn’t rise to the level of requiring throwing out the foundation of biology. You need to read Thomas S. Kuhn “The Structure of Scientific Revolutions” to see what it would take to change the paradigm of evolution. BTW, he is the origin of the word paradigm. It is available online.


(Ashwin S) #77

If evolution is true, how many creature should there be between something like a pakicetus and a modern whale?
Even a 100 intermediate creatures should be a low guess… 1000s would be more appropriate. The question to ask is where are 99% of the intermediates that should be there?
The sheer diversity in nature should enable scientists to find a few creatures that look like an intermediate species. It could be argued that they seem to be finding, creatures that happen to have seemingly intermediate features and forcing them into a story…
Unless evolution happens through immense leaps, the “evolution” stories are like a few threads here and there being used to show a trapestry.

I agree that a paradigm shift is needed. Instead of forcefully interpreting everything along evolutionary lines, people need to ask tough questions.
I believe it’s slowly happening. As scientists learn more about genomes and how genes are regulated, I expect things to change.


#78

This might be true if palaeontologists searched the whole earth trying in vain to find an intermediate species. Truth is they don’t work that way. They target their search using the theory of evolution to determine when and where the fossils should be and then go out and find them. Read George’s post #14 in this thread. In fact read “Your Inner Fish” by Neil Shubin if you really want to understand this. A great book by the way.

You really need to read Kuhn. There is nothing indicating that a paradigm shift is in the works.


#79

We have an abundance of intermediate fossils. Where have you been?


(Matthew Pevarnik) #80

Fish have eyes. Such cave fish would share a common ancestor with other fish.

To see.

Cavefish have eyes that don’t develop. Even if you grow and breed them outside of dark caves they don’t start developing their eyes again.

What do you think this article shows? It actually demonstrates quite convincingly that they had an ancestor that once had eyes. Much in the same way that we gave chicken their teeth back:
https://www.nature.com/scitable/topicpage/atavism-embryology-development-and-evolution-843

I don’t think I can, sorry. I posted their updated phylogenetic tree and I focused in on the left lineage where they realized there was just one appendix appearance that was passed down through common descent. Some of that lineage lost the appendix due to its vestigiality and lack of positive natural selection, demonstrating well common descent and that the appendix can be and has been vestigial for many mammals.

Yes I know. They mean among mammals as a whole but it’s clear the appendix has been lost for individual lineages! In those lineages it can indeed be considered vestigial where their ancestors kept it due to positive selection and then they lost it.

I see. Why don’t you question your predetermined conclusion that common ancestry is false? It seems that you base your conclusion not really on any scientific data but instead how you interpret some Scriptures in the Old Testament- which with your predetermined conclusion you filter through scientific papers and seem to believe that you have an expertise that far exceeds people who actually are actually experts in various fields. I used to do that too, where I would read scientific papers and imagine that I knew far more than the people who wrote the paper and they were just as blind as those cave fish to the Truth.

This also highlights and important part of science where no scientist can just take a single experiment and imagine a result, but this is a large body of interconnected ideas. If you wish to change a large explanatory framework, you must be able to explain all the existing data even better than what presently exists. Unfortunately there is not such explanation for the scientific hypothesis of the Intelligent Designer who just does things in a pattern that appears to match evolutionary predictions.