Do monkeys and apes have an appendix?

There’s always someone on a nature show saying that if a trait survives to the next species it must have value. Then they try to rationalize it. If nothing else makes sense, they stick a lot of strangeness to “used to attract mates”.

A disproof of that would be if apes and monkeys had appendixes.

So, do they?

Apes, like orangutans, chimps, and gorillas, have appendixes (appendices?). Monkeys don’t.

An interesting theory I heard that makes sense to me (sorry, I don’t have a cite) was this:

For an appendix to “evolve away” one would expect that it would in successive generations it would become smaller and smaller. However, if an appendix is small, the narrowness of the opening would make it more likely to get obstructed and thus prone to infection. So while a species would be better off with out an appendix, a small appendix would be a disadvantage and a larger one, although useless, would be an advantage.

Sometimes traits hang around just because they happen to be there and do no harm.

“Sometimes traits hang around just because they happen to be there and do no harm.”

Yes, that is my point exactly.

And it’s also exactly why I think your other cite is just wishful thinking. It tries to justify the appendix as needed in some minor way. But why go to those contortions at all. Things do not need any survival value to continue on. They only need to lack deadly risks. The selection is done to remove things that have risk, not merely things with no value. That’s why so many animals have tails they have no real need for. Manx cats do fine without tails, yet all their kin have them- why? because they don’t kill the cat.

You can’t necessarily trust “someone on a nature show” as having the Straight Dope on every aspect of their subjects’ behaviour, anatomy or physiology. It’s not true to say that “if a trait survives to the next species it must have value” – there’s such a thing as a vestigal body part after all (the tiny remnants of legs in certain snakes, the non-functioning eyes of animals that live in total darkness etc.)

Anyhow, the appendix may not be the best example to disprove the claim because as far as I know it’s not considered to be a vestigal organ these days. You’ll have to wait for an approprately-qualified person to come along explain why. All the same it seems unfair for you to condemn a comment that the appendix performs a purpose is “wishful thinking” or “a contortion” – either it does a job or it doesn’t wherever people stand on the creationist/evolutionist debate.

The appendix has some heavy-duty lymph connections, so it may have a role in the immune system. Completely anecdotally, since my husband had his removed, every little damned thing throws his intestines out of whack. (I’ll stop there, lest we enter the land of Too Much Information.)


The tail DOES serve a function as a balancing organ and mood indicator for other cats. While the lack of a tail is not crippling, most cat species get along better with one than without.

Riiight. And apes too, I suppose?

I don’t get it. How does an ape or a monkey having an appendix disprove that it has utility?

You sure do sound hostile…
Anyway, I think your point is moot.

My reading of the OP is that he’s asking whether or not “someone on a nature show” is right about evolution.

Hardly a water-tight reference for evolutionary theory…

Not only is the OP hostile, but is apparently incapable of sustaining or understanding a reasoned argument. Sock Munkey’s post was obviously a contradiction of his claim that cats’ tails serve no purpose, not a claim that apes have (or ought to have) tails.

I don’t get the reasoning behind this.
A trait that survives to the next species (or any other arbitrary evolutionary checkpoint) has only to be passed from individual to offspring successfully many times, and for it to do that, the only real requirement is that it not prevent the organism from mating before it has a chance to, by death or any other means. There’s no mechanism that stops genes and checks them for “usefulness”; genes get passed on if an organism reproduces and that is that, unless mutations occur, but that has nothing to do with whether the trait a gene (or genes) encodes is “useful” to the organism.
I really don’t see any logical assumptions upon which this statement could be based, and quite honestly, I doubt it was ever made on any nature show, or by anyone that claims to know anything of biology. This may be based on the general misconception that evolution equals “getting better,” which is absurd but unfortunately quite widespread.