The Human Tail and Other Tales of Evolution

Editor’s Note: First published in St. Louis MetroVoice 4, no. 1 (January 1994).

In the May 20, 1982, issue of The New England Journal of Medicine, Dr. Fred Ledley, M.D. presented a clinical case report titled “Evolution and the Human Tail.” Ledley’s report concerned a baby born with a two-inch long fleshy growth on its back, bearing a superficial resemblance to a tail. Ledley strongly implied that this growth (called a caudal appendage) was essentially a “human tail,” though he admitted that it had virtually none of the distinctive biological characteristics of a tail!

All true tails have bones in them that are a posterior extension of the vertebral column. Also, all true tails have muscles associated with their vertebrae, which permit some movement of the tail. Ledley conceded that there has never been a single documented case of an animal tail lacking these distinctive features, nor has there been a single case of a human caudal appendage having any of these features. In fact, the caudal appendage Ledley described is merely a fatty outgrowth of skin that wasn’t located in the right place on the back to be a tail! Still, Ledley saw his caudal appendage as providing compelling proof for the evolution of man from our monkey-like ancestors. He said that

even those of us who are familiar with the literature that defined our place in nature (Darwinism)—are rarely confronted with the relation between human beings and their primitive ancestors on a daily basis. The caudal appendage brings this reality to the fore and makes it tangible and inescapable.

Is there any branch of science, other than evolution, where such trivial data can be extrapolated into such profound and “inescapable” facts?

As recently as 1971, the Encyclopedia Britannica claimed that there were more than 100 vestigial organs in man.

The “human tail” is just one example of what evolutionists call a “vestigial organ.” As the name suggests, these organs are supposed to represent useless remnants of what were once functional and useful organs in our primitive ancestors. As recently as 1971, the Encyclopedia Britannica claimed that there were more than 100 vestigial organs in man. Even critically important organs such as the thymus and parathyroid glands were once considered to be vestigial simply because their functions were not understood. As biomedical science has progressed, there are fewer and fewer claims of function-less organs. Despite their diminishing numbers, vestigial organs are still mentioned in textbooks as one of the strongest evidences for evolution and against intelligent design by a Creator. The most frequently cited examples of vestigial organs in man are the coccyx and the appendix.

The human coccyx, or “tail bone,” is a group of four or five small vertebrae fused into one bone at the lower end of our vertebral column. Most of us never really think about our “tail bone” until we fall on it. Evolutionists are dead certain that the coccyx is a vestige of a tail left over from our monkey-like ancestors. The coccyx does occupy the same relative position at the end of our vertebral column as does the tail in tailed primates, but then, where else would it be? The vertebral column is a linear row of bones that supports the head at its beginning and it must end somewhere. Wherever it ends, evolutionists will be sure to call it a vestigial tail.

Most modern biology textbooks give the erroneous impression that the human coccyx has no real function other than to remind us of the “inescapable fact” of evolution. In fact, the coccyx has some very important functions. Several muscles converge from the ring-like arrangement of the pelvic (hip) bones to anchor on the coccyx, forming a bowl-shaped muscular floor of the pelvis called the pelvic diaphragm. The incurved coccyx with its attached pelvic diaphragm keeps the many organs in our abdominal cavity from literally falling through between our legs. Some of the pelvic diaphragm muscles are also important in controlling the elimination of waste from our body through the rectum.

Another common evolutionary claim found in textbooks is that the human appendix is really a vestigial cecum left over from our plant-eating evolutionary ancestors. The cecum is a blind-ending pouch near the beginning of the large intestine, which provides additional space for digestion. In some plant-eating animals, such as cows, the cecum contains special bacteria that aid in the digestion of cellulose. The appendix is clearly not a vestigial cecum because almost every mammal has a cecum and many of these also have an appendix! Man, for example, has both a cecum and an appendix—neither is vestigial or useless. The appendix, like the once “vestigial” tonsils and adenoids, is a lymphoid organ (part of the body’s immune system) that makes antibodies against infections in the digestive system. Believing it to be a useless evolutionary “leftover,” many surgeons once removed even the healthy appendix whenever they were in the abdominal cavity. Today, removal of a healthy appendix under most circumstances would be considered medical malpractice.

The presence of rudimentary organs in the adult do not tell us something about evolution, but rather tell us something about embryology.

There are organs in the body that have no known function in the adult but are still not vestigial in the evolutionary sense. For example, poorly developed and inactive mammary glands are found in adult males of all mammals, including man. Even evolutionists do not believe that these rudimentary glands are vestigial mammary glands left over from female ancestors of males, nor do they believe that males once nursed their young. There is a much better explanation for the male mammary gland. Males and females develop from nearly identical embryos, which, at an early stage of development, become either male or female under the influence of genes in the sex chromosomes. The same parts of an embryo may produce either male or female sex organs and mammary glands. In humans, almost every component of female sex organs can be found in a rudimentary form in the male; and the reverse is also true. Thus, the presence of rudimentary organs in the adult do not tell us something about evolution, but rather tell us something about embryology.

In conclusion, the “vestigial” status of many organs has often been merely a way of covering up our ignorance of their true function. Unfortunately, there is little inclination to investigate the functional significance of organs believed to be “useless.” There are now few, if any, organs that are considered to be functionless in both embryo and adult. Even if vestigial organs were to exist, they would not provide evidence for evolution but rather for devolution. The problem for evolutionists is not how useful organs are lost, but how evolution produces new useful organs with all their integrated complexity. It is here that we find evolutionary tales.