Okay, I know the vertebrate tail has been adapted to many different and wonderful uses. Fish and flying birds use it as a rudder. Kangaroos and cheetahs use it as a counterweight. For peacocks it’s a mating display. New World monkeys have prehensile tails. And don’t some reptiles’ tails serve as cooling fins?
But, for the majority of land vertebrates, I just don’t see where there’s a selective advantage. Felines, canids, ursines, ungulates, ruminants, hippos, rhinos etc. have tails that serve no obvious purpose other than protecting the anus. And they’re usually much longer than would be necessary just for that purpose.
Natural selection has had plenty of time to get rid of the tail if there’s no selective advantage. And I can even see a slight selective disadvantage, since a prey animal with a tail has that much additional body for the predator to grab ahold of.
So why do my (non-Manx) cats still have something to twitch at me when I piss them off?
WAG: Balance. Also, some animals use their tails as signals to let others know what’s going on. My Dog’s tail seems to have evolved specifically to knock things off my coffee table.
Balance, communication are the only two things I can think of. A cat uses it’s tail to right itself when falling. For dogs it’s a major part of their communication (cats to some extent too). Hippos? No idea.
Actually, humans have tails too. Early in the development in the womb humans have tails for awhile and then it goes away (didn’t the X-Files have a guy with a tail once?).
Although tails may confer no advantage they confer no disadvantage either so Mother Nature is slower to getting around to removing them through evolution.
I won’t bother asking satan, but now I know what the rings of Saturn are for,planets being tailess and all and the comets so infrequent…
Cheetas are felines, the feline tail is primarily for balance when running, also for signaling, the canine tail is mostly the opposite. Most other predators use it for balance. for the skunks its mostly a signal. Ursines aint got enough tail to consider. the ungalates, including the ruminants, use it as a flyswish, also for signaling, especially the short tailed ones like deer. In some deer it covers scent glands.By raising and lowering and waving the “lid” they can signal each other when they can’t see each other. Rodents use it for balance and some for leaving a scent trail. Koffing was on the button. Hippos spin theirs like a propelor, it’s paddle shaped and flings the stuff 5 to 10 meters. DUCK! burt tails are probably just due to inattention on the assembly line. Assembling vertabrae is the most boring part about building animals. Wrkers tend to “drift off” next thing you know, “Oops, too many.”
It’s cheaper just to leave them hanging off the back than waste time disasembling,especially since they can’t be re-used anyway.
“Pardon me while I have a strange interlude.”-Marx
Another example that occurs to me: Porcupines use their tail for defense. They shake the tail back and forth. Quills are dislodged from the tail, giving the appearance of being thrown at the attacker.
Natural selection does select IN, it selects OUT.
You don’t get traits that would be useful, you lose those that harm your chances of survival, and then only past the age of first reproductive cycle. A trait that kills on second offspring will still get passed on to the first.
Natural selection doesN’T select IN, it selects OUT.
You don’t get traits that would be useful, you lose those that harm your chances of survival, and then only past the age of first reproductive cycle. A trait that kills on second offspring will still get passed on to the first.
Monkeys use their tails all the time. To help them hang onto trees and so do many tree dwelling creatures. Obviously natural selection has proven that tails do help for climbing, and balancing.
Humans evolved so that they stand upright. Maybe that meant that the tail wasn’t as usefull, or maybe it would make humans unbalanced if they had tails.
Well, most land vertebrates have tails because the basic architecture is an elongated structure (spine) with a head at one end and the legs are attached at points around the middle of the structure, not at the very ends. Yet we’re pretty sure about the usefulness of necks, and question that of tails.
Now, many amphibians and reptiles – salamanders, lizards, crocodiles – have quite substantial tails, and it clearly looks like what it is: the body continuing on. Birds have relatively short tails, skeleton-wise, most of the length being provided by feathers (for control in flight).
On some land vertebrates the tails have become so rudimentary they are absorbed into the rump in the adult form, yet they are present in the embryo (e.g. frogs, apes).
One thing I seem to notice in the vertebrate pattern is that no vital organ seems located behind the pelvic girdle, i.e. inside a tail. This makes evolutionary sense in that the space between the sets of limbs is better protected. So the basic model is there are tails as a basic fact, and then there are lots of variations on tails up to and including their being so rudimentary they are internal. As to why, well, some population of creatures with each particular tail mutation was able to reproduce successfully.
I liked the Calvin-and-Hobbes answer: “So, it’s like a necktie for your butt?”
Another WAG, building off JRDelirious: Defense. When a predator attacks, it’s handy to have a less-needed apendage for them to mistakenly grab.
Thus, unless a species has a selection pressure towards a shorter tail (like apes that travel upright at times), a longer tail might lead to better survival odds.
Most cats have tails, but Manx cats don’t.
And they seem to do quite well.
Wouldn’t this prove you don’t really need a reason for everything? Some things just happen, by the whims of chance.
Either that or it means that Manx cats don’t live live in the same environment that their ancestors or cousins did.
Perhaps less treetop work, more snoozing on sofas?
I realize this. My point was that mammals like us had a selection pressure to lose our tails.
And if you look at an ape or human skeleton, there is a tail, of sorts. The coccyx is a bone made up of short fused vertebrae. It’s just too short to protrude.
Sorry, I didn’t mean to be pedantic. Humans have the tailbone just as we have an appendix. I guess I have a problem with lumping so many diverse creatures into “we” when apes and humans common ancestor lost of the tail so long ago. The evolutionary bush is so diverse that by the time you get back to the guy who had a tail he may have been a lemur or something.
Would their be “selection pressure to lose our tails”, or were Homonids able to walk upright because they had no tails?
I guess a good example is that giraffes did not grow a long neck to eat higher leaves, they are able to eat higher leaves because they evolved a longer neck.
