English Deutsch Français Italiano Español Português 繁體中文 Bahasa Indonesia Tiếng Việt ภาษาไทย
All categories

why dont we all have tails that would be so cool

2007-03-13 06:04:10 · 9 answers · asked by rollin with the homies 2 in Science & Mathematics Zoology

9 answers

Actually, we do have tails, in a vestigial form. As Darwin put it in “The Descent of Man,” “A tail, though not externally visible, is really present in man and the anthropomorphous apes, and is constructed on exactly the same pattern in both.”

He was referring to the coccyx, rightly known in the vernacular as the “tail bone.” This string of (usually) three or four rudimentary vertebrae forms a pointed curve at the base of the spine in humans and apes (such as the chimpanzee and gorilla). The coccyx is of course entirely contained by the body, and cannot be moved like a full animal tail.

Even before Darwin, the coccyx was regarded as one of the prime pieces of evidence for humankind’s relationship to animals. In skeletal, muscular, vascular and nervous structure, it is homologous to the tails of other animals in general and of monkeys in particular.

However, it’s not simply a withered tail. The coccyx serves as an anchor for muscles that support the viscera and close off the back of the pelvis. At least some of these muscles, the ileo-coccygeus sheet, are clearly adapted forms of the muscles that, in monkeys, allow the tail to be moved from side to side.

Human evolutionists are certain that the oldest direct ancestor of humans and apes, probably around 20 million years ago, possessed a tail. We know where it went, but why did it go?

Nobody’s ever gotten farther than Darwin’s general hypothesis that tail modification was “directly connected” with the development of semi-erect postures in apes and a fully erect posture in humans. (The fossil record indicates both changes occurred early on, if not simultaneously.) Monkeys and lemurs, our other close cousins, use their tails to balance and brake themselves while leaping. But the early apes took to swinging arm-over-arm through the trees and spending time on the ground, probably making a tail unnecessary and more useful as an anchor for extra pelvic-support muscles. (A couple species of ground-dwelling monkeys possess only stubs of tails.)

But a body part doesn’t disappear just because it’s outdated, and it’s hard to see extra pelvic support as a significant selective advantage. Almost all monkeys and lemurs sit or stand upright for short periods of time without their guts popping out.

It’s probably a mistake to focus only on the coccyx. The spine has gone through a lot of changes, including the sacral vertebrae fusing into a single bone just above the coccyx. The body is an entire system that can often change in multiple, unpredictable ways when only one part is gaining a selective advantage.

It’s possible the transformation of the tail was a genetic byproduct of the larger pelvic mutations that made upright posture possible, or of a completely different change altogether. The decoding of the human genome may one day tell the tail’s tale.


In shorter ways we don't have tails because aniamls with tails use it for balance. And we don't need so much balance because we stand upright with our 2 feet.

2007-03-13 08:43:35 · answer #1 · answered by Anonymous · 1 0

actually you do. although it's a vestigial one. It's called the coccyx or tail bone. Our body doesn't need it anymore so as we evolved, it shrunk. Just like your appendix. It used to be a useful part of the digestive system when our ancestors were eating raw meat. Since we now cooked our food, in time, the appendix also shrunk.

2007-03-13 13:46:44 · answer #2 · answered by lycan_888 2 · 1 0

None of the great apes have tails. (Gorillas, bonobos, Chimps, Orangutans, Humans)

I think we lost them over the millions of years when we were walking upright, since most primates with tails use them for balance.

I'd love to have a prehensile tail. I would hold my wine glass with it.

2007-03-13 13:08:23 · answer #3 · answered by Year of the Monkey 5 · 4 0

You do it is called your tail bone. Also, what would you use it for? Just wondering

2007-03-13 14:21:05 · answer #4 · answered by puggylover 4 · 0 0

We've evolved. We don't need tails anymore so they're vestegial structures now.

2007-03-13 13:21:50 · answer #5 · answered by comicfreak33 3 · 0 0

you do have a vestigial one; the coccyx or tail bone, is what we have.

2007-03-13 13:09:15 · answer #6 · answered by Anonymous · 2 0

I'm suprised that you don't have one, asking questions like this.

2007-03-13 13:12:55 · answer #7 · answered by Kate, the one and only 2 · 0 2

some do

2007-03-13 13:09:14 · answer #8 · answered by Astalav 1 · 0 0

ASk your mom; she probably docked it.

2007-03-13 13:07:57 · answer #9 · answered by wizjp 7 · 0 4

fedest.com, questions and answers