Human tails and fairy tales
Have there really been people with functioning tails, and if so, are they vestigial?
Illustration by Arcadian, wikipedia.com
Irvin W of Manitoba, Canada was unsettled by a report he encountered from the notorious anti-creationist TalkOrigins website, about humans with tails—movable tails allegedly replete with vertebrae and muscles. Andrew Lamb replies.
How do you respond to people that try to prove human evolution by their tailbones that protrude from the backside. At the following URL: [deleted in accordance with CMI feedback rules] there is an x-ray of a baby with a mutated tailbone that is apparently longer than a normal spine. This x-ray does not really show what part is visible protruding from the body but is there a good rebuttal for this argument? The picture of the "Whale leg" bones on this page does not seem to me to be evidence because the bones could have come from some other animal while the picture of the dolphin with flippers can be easily shown to be a non information gaining mutation.
Thank you for your email of 27 August, submitted via our website.
How do you respond to people that try to prove human evolution by their tailbones that protrude from the backside. At the following URL: [deleted in accordance with CMI feedback rules]
Much of the material on the TalkOrigins website is either woefully out-of-date, or severely misleading, or both. For a typical example, see our article Evolution by fiat and faith, which deals with a meretricious century-old claim about speciation in evening primroses. The particular webpage1 you referred to is a case in point, having not merely interpretations with which we disagree, but information that is out of date, and facts that are presented in such a way as to almost certainly leave the reader with a wrong impression. TalkOrigins is a source of many of the spurious objections that witnessing creationists continually encounter. As one former atheistic evolutionist put it, most evolutionists use the TalkOrigins website as their ‘Bible’. Creationist refutations of many of their claims are available on the TrueOrigin website.
there is an x-ray of a baby with a mutated tailbone that is apparently longer than a normal spine.
In fact that x-ray shows a normal healthy spine, as admitted in the original research paper by Bar-Maor et al. from which that x-ray image (Figure 3 in the paper) was taken.2 Doubtless other readers of that webpage will have gained the same incorrect impression that you (and I, at first) got, namely that there exist people whose coccyxes (or ‘tailbones’) are longer than normal and form the core of a protruding and movable appendage, i.e. a functioning tail. This turned out not to be the case. And as a modern embryology textbook notes, ‘Rarely a caudal appendage is found at birth. Such structures are of varied origin (some are teratomata); they practically never contain skeletal elements and are in no sense tails.’3
Caudal appendages occur in around 1 to 3 people per thousand. Most consist of skin and fatty tissue, and are located 1.5 centimetres from the midline of the back. Many are removed surgically shortly after birth.
The Bar-Maor paper discusses three patients, all children:
- Child 2 was a three-month old baby, with a coccyx of three vertebrae, plus a soft caudal (lower back) appendage a few centimetres long lying flush against the body. There were ‘no pathological findings’ (i.e. no disease or pain) and the coccygeal vertebrae were ‘well-developed’. For cosmetic reasons, the parents had the appendage surgically removed.
- Child 3 was a six year old girl. She also had a coccyx of three vertebrae, plus a soft caudal appendage. The researcher described her condition as being the same as that of Child 2, so her caudal appendage was presumably also a few centimetres long, and lying flush against the body, and her coccyx healthy and well developed. There was no pain and no cosmetic complaint, so surgery to remove the appendage was not undertaken.
- Child 1 had a long coccyx consisting of five vertebrae, but no caudal appendage, i.e. no ‘tail’. He was prone to occasional pain at the base of his spine, especially if he had been sitting on hard concrete surfaces. Surgical shortening of his coccyx was considered, but not undertaken, because his parents felt their son’s symptoms were not sufficient to warrant surgery.
This x-ray does not really show what part is visible protruding from the body but is there a good rebuttal for this argument?
The x-ray that appears on the TalkOrigins webpage is of Child 3, who had a healthy, well developed coccyx. Being soft tissue, Child 3’s benign caudal appendage does not appear in the x-ray, except perhaps to the trained expert eye. What does appear is the normal healthy coccyx, albeit of only three bones—most of us have four coccygeal vertebrae; a few percent of people have five and a few percent have three.4
Alarmingly, despite Child 2’s coccyx being normal and healthy, the Bar-Maor paper goes on to say that part of the coccyx was removed during the surgery, i.e. not just the fatty caudal appendage was removed.5 I say ‘alarmingly’ because unnecessary removal of part of the coccyx can have potentially tragic consequences. This danger had long been recognised in sober medical circles at the time Bar-Maor and colleagues published their paper in 1980. As one writer commented in 1961:
Take it away and patients complain; indeed the operation for its removal has time and again fallen into disrepute, only to be revived by some naive surgeon who really believes what the biologists have told him about this useless ‘rudiment.’6
In the past, bolstered by the idea that this organ was vestigial and unneeded, surgeons would sometimes remove a person’s coccyx peremptorily (as was once done routinely with tonsils). But this results in severe problems for the patient, because the coccyx serves as a crucial anchor point for various important muscle groups. Victims of coccygectomy (tailbone removal) in the past have had as a consequence difficulty sitting down and standing up, difficulty giving birth, and difficulty getting to the toilet in time.7 Nowadays, coccygectomies are only performed as an extreme last resort, and involve reattachment elsewhere of the crucial muscles. For more on the functions of the coccyx see Do any vestigial organs exist in humans?
Both the TalkOrigins webpage and the original Bar-Meor paper promulgate the false idea that in the womb people have an ‘embryonic tail’. The correct term for the structure in question is the caudal eminence. They claim it contains extra somites8 (the embryo's bead-like somites are precursors to several different structures, including vertebrae) and that if these continued growing instead of degenerating and getting reabsorbed that they would develop into extra tail bones, adding to the regular three to five coccygeal vertebrae that develop normally. They thus call these features ‘coccygeal somites’. But since they do not develop, it is pure evolution-inspired supposition to presume to know what they would develop into, and to label them ‘coccygeal’. As one modern human embryology textbook puts it, ‘Supernumerary vertebral centra that would later degenerate are not present and hence no tail exists’9 and ‘the caudal tip of the trunk appears particularly tapered at 5 weeks, because it contains merely neural tube, but is in no sense a (future) vertebrated “tail”.’10 Only three to five bones have ever been recorded in the human coccyx.
Photo by berniegreen, istockphoto.com
Even if there were/are several extra incipient caudal vertebrae that disappear before birth, such structures could have a purpose unrelated to that of vertebrae in grown people. Several examples are known of organs appearing and then disappearing during embryonic development. Generally the organs involved seem to play a structural role in the development of parts of the body. For example embryonic baleen whales have teeth which serve as a sort of scaffolding for the growth of their massive jaws, but these teeth disappear by the time they are born—see Teeth in embryonic baleen whales. Grown baleen whales are filter-feeders, with baleen and no teeth.
Several sorts of anatomical anomalies are caused by developmental processes finishing up earlier than usual, or continuing on for longer than usual. Having one fewer or one extra coccyx bones may be an example of this type of thing. This may be aberrant, or it may be within God’s original designed range of physical variety within humans. There are genes known as control / switch / signalling genes that regulate the number of digits, limbs, etc. that people and animals grow. Interfering with these signalling genes (dozens are involved) can result in non-typical numbers being produced. See Hox (homeobox) Genes—Evolution’s Saviour? This signalling is a big-cast high-precision ballet of ‘intricate overlapping patterns’ and ‘unimaginable complexity’, resembling ‘a tangle of circuits that loop vertiginously across time and space’.11
From fossils we know that amongst horses in the past there was a considerable range in the number of lumbar vertebrae, from as low as 15 to as high as 19. But virtually all horses today have 18 lumbar vertebrae—see What’s happened to the horse? The former variation was probably part of the original created variety within the horse kind, and not abnormal.12,13
Photo by Magnus Manske, wikipedia.com
In contrast, there are some variations that are almost universally considered aberrant. From the ancient past to the current day there have been recorded cases of people with six fingers and/or six toes (see polydactyly box). Most creationist scientists think this is abnormal, rather than part of the original created variety within humankind.
In a high percentage of cases, people with a caudal appendage will also have another medical condition too, such as spina bifida, in which a vertebra is incompletely closed.14 People with caudal appendages, spina bifida, and other conditions are not regarded as more highly evolved. In fact many thousands of human genetic mutations have been identified that are causatively linked with crippling and lethal diseases15, and yet the basic premise of neo-Darwinian evolution is that such mutations provide the material from which natural selection will bring forth upward evolution!
Note that even if there occurs or has occurred a case of a person having a movable tail-like caudal appendage containing bone, that does not mean the appendage is vestigial. And even if human caudal appendages were vestigial (which they are not) this would constitute degenerative change (loss of an organ) whereas evolution requires generative change, producing new types of organs that did not exist before. See our Q&A: ‘Vestigial’ Organs page.
These ‘even ifs’ indicate assumptions on the part of evolutionists. Caudal appendages and short and long coccyxes are facts—observable, measurable, and hence scientific facts. But the idea that they are vestigial (evolutionary ‘left-overs’ or ‘throwbacks’) is pure assumption. And the idea that a vestigial organ would be evidence of evolution is just fallacious logic. Evolution would require nascent (beginning development) organs of new types, not degenerate or aberrant organs of existing types.
The picture of the "Whale leg" bones on this page does not seem to me to be evidence because the bones could have come from some other animal
We think that photo of anomalous bones taken from a whale is genuine. There is no reason to doubt the veracity of the facts of the case reported in the original research paper16 though of course we reject the evolutionary interpretation of these bones as vestigial legs. For discussion of another case of alleged leg bones in whales, see The strange case of the leg on the whale. This case was also based on a modicum of osteological evidence. For a recent legged-whale claim based on no physical evidence, see The legs that weren’t.
while the picture of the dolphin with flippers can be easily shown to be a non information gaining mutation.
Yes. For a discussion of this case, see A dolphin with legs—NOT.
Both evolution and creation are worldviews / meta-theories / paradigms, used to explain the multifarious scientific facts. Many people don’t recognize this, but as philosopher Karl Popper in his autobiography stated, ‘I have come to the conclusion that Darwinism is not a testable scientific theory but a metaphysical research programme.’17 The facts of science fit snugly with creation, while there is much data that clashes starkly with the idea of evolution. Nevertheless, historical events are ultimately unprovable scientifically, and so this leaves room for a large measure of faith in deciding what you will believe. See ‘It’s not science!’
Incidentally, herein lies a big weakness of the Intelligent Design Movement—Since the past cannot be scientifically proven, and both paradigms purport to explain our existence, well, why not believe in evolution and millions of years? Since both paradigms can ‘explain’ all the data (albeit one badly and one well), then unless you have a true version of history (the Bible) with which to replace the false version of history (evolution and millions of years) there is no imperative to drop evolution and adopt design. Indeed, since design entails a Designer to whom we therefore belong, and to whom we are therefore accountable for our actions, there is a strong incentive to prefer naturalism (evolution), given our natural bent to do our own thing; to turn our backs on God. See CMI’s views on the Intelligent Design Movement.
I trust this helps.
Sometimes people are born with more than five fingers on a hand, or more than five toes on a foot, a condition known as polydactyly. For a modern example of a six-toed but otherwise normal-looking and even aesthetic foot, see The amazing six-toed foot of Girl H. Many instances of polydactyly are due to developmental abnormalities in the individual. Some forms of polydactyly are genetic and heritable.18,19
One idea is that variation in the number of digits was part of the original genetic make-up of people, but that due to the ‘genetic bottleneck’ effect of the Flood, instances of people with other than 20 digits became rare after that event. However, it seems more likely that six digits was not part of the original created variety within the human genome. The Bible records two cases of giants with six fingers and toes, in 2 Samuel 21:20 and 1 Chronicles 20:6. Some Bible scholars would take these verses together with the Genesis 6:1–4 passage as indicating that six digits was not part of the original created variation within humankind.
Most people in the medical professions consider more than five digits to be an abnormality, rather than upward evolution.
- Example 2: Newborn babies born with tails, <www.talkorigins.org/faqs/comdesc/section2.html
#atavisms_ex2>. Return to Text.
- Bar-Maor, et al., Human tails, Journal of Bone and Joint Surgery, British Volume 62-B(4):508–510, November 1980, http://www.jbjs.org.uk/cgi/reprint/62-B/4/508.
- O’Rahilly, R. and Müller, F., Human Embryology
& Teratology, Second Edition, Wiley-Liss, 1996; page 93:
Between 4 and 7 weeks the caudalmost part of the trunk tapers, probably as a result of a precocious growth of the neural tube. The proximal part of the projection contains some coccygeal vertebrae16,17, whereas the distal portion, although it contains neural tube, is non-vertebrated. By the end of the embryonic period23, the vertebral column has lengthened relative to the spinal cord so that both end at the same level. Moreover, the surrounding tissues have increased in volume, cellular death has occurred, and the former tip of the trunk is now more or less flush with the general surface. Rarely a caudal appendage is found at birth. Such structures are of varied origin (some are teratomata); they practically never contain skeletal elements and are in no sense “tails.” Projections that contain skeletal elements are caused by a dorsal bending of the coccyx, do not contain more vertebrae than normal, and have nothing to do with “atavism” (Hornitzki). (pages 93–95) Return to Text.
- Moore, K.L. and Persaud, T.V.N., The Developing Human:
Clinically Oriented Embryology, Saunders 2003, page 388:
About 95% of people have 7 cervical, 12 thoracic, 5 lumbar, and 5 sacral vertebrae. About 3% of people have one or two additional vertebrae and about 2% have one fewer. To determine the number of vertebrae, it is necessary to examine the entire vertebral column because an apparent extra (or absent) vertebra in one segment of the column may be compensated for by an absent (or extra) vertebra in an adjacent segment; for example, 11 thoracic-type vertebrae with six lumbar-type vertebrae. Return to Text.
- Alternatively, ‘well-developed’ could mean ‘having large processes’. If the caudal appendage was attached to the body along its length, rather than merely lying flush against it, then perhaps some well-developed processes from the coccyx bones could be sticking into the appendage, in which case ‘excising part of the coccyx’ could have meant trimming down the protuberances, while leaving all three coccyx bones in place. This whole scenario seems unlikely to me, but the Bar-Maor paper is ambiguous as to exactly what part of the coccyx was removed, and why. Andrew Lamb. Return to Text.
- Shute, Evan, Flaws in the Theory of Evolution, Craig Press 1961, page 40; cited in Ref. 7, page 34. Return to Text.
- Bergman, J. and Howe, G., “Vestigial Organs” Are Fully Functional, pages 32–34, Creation Research Society Books, 1990. Return to Text.
- Three weeks after conception a double line of somites begins forming along the back, either side of the neural tube. These somites are bead-like blocks of mesodermal cells that act as centres of growth. Various organs and tissues grow from these somites. Many pairs of somites are involved in producing vertebrae, but not all of them. Many embryology textbooks refer to somites beyond those that form the coccyx, but it is not entirely clear to me whether the structures they are referring to are in fact somites, or whether they are segments of the long caudal neuropore, which extends beyond where the somites end, forming the caudal eminence, and which is similar in appearance to the somites. Doubtless any somites beyond those that form the fourth or fifth coccygeal vertebrae would have some important but as yet unelucidated role in development. Andrew Lamb Return to Text.
- Ref. 3, page 336. Return to Text.
- Ref. 3, page 331:
Somites first appear at 3½ weeks9, and approximately 30 pairs are present at 4½ weeks13. The full complement comprises about 38 or 39 (rather than 42–44) pairs but they are never all visible at one time: 4 occipital, 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and usually 4 or 5 coccygeal. The coccygeal somites do not at first reach the end of the body. The caudal tip of the trunk appears particularly tapered at 5 weeks16, because it contains merely a neural tube, but is in no sense a (future) vertebrated “tail.” By 7 weeks19 only a caudal rudiment remains and the caudal end of the trunk is becoming smooth. This is probably brought about by regression of part of the neural tube (and perhaps extrusion of a portion through the skin), as well as by further growth of the coccygeal somites or vertebrae. Caudal appendages found as an anomaly at birth are discussed in Chapter 8. (pages 331–332) Return to Text.
- Leroi, A.M., Mutants: On the Form, Varieties and Errors of the Human Body, Harper Perennial 2005, pages 124, 126, 127. Return to Text.
- Kardong, K.V., Vertebrates: Comparative Anatomy, Function,
Evolution, Third Edition, McGraw Hill 2002; pages 305–307:
In mammals, the vertebral column is differentiated into distinct regions. Typically, mammals have seven cervical vertebrae, beginning with an atlas and axis that permit the head great freedom of movement. Even the long-necked giraffe and “neckless” whale have seven cervical vertebrae, although exceptions occur in sloths (with six to nine) and sirenians (with six). In armadillos and many jumping mammals such as kangaroo rats, the seven cervical vertebrae may fuse. The number of vertebrae within the thorax and lumbar regions ranges from about 15 to 20, and there are usually two or three sacral vertebrae, although humans have five. The caudal vertebrae are quite variable in number. The mammalian tail is much less massive than the reptilian tail. Arches, zygapophyses, and transverse processes diminish toward the posterior tip of the tail so that most caudal vertebrae near the end of the series consist only of centra. Return to Text.
- Kent, G.C. and Carr, R.K., Comparative Anatomy of the
Vertebrates, Ninth Edition, McGraw-Hill 2001, page 154:
Among mammals, there are as few as three caudal vertebrae and as many as 50. The tail of sperm whales has 24. Apes and humans have four or five vestigial [!] caudal vertebrae comparable to the pygostyle of birds. These caudal vertebrae lack arches, but most of them have rudimentary transverse processes. The last three or four diminish progressively in size and, in humans, they fuse with one another to form a rigid coccyx at about 25 years of age. The centra of the coccyx are still identifiable, but the last one is a mere nodule of bone. People whose “tailbone” is recurrently sore have fractured the coccyx at some earlier date in a fall that caused them to land on the end of their spine. In contrast to hominoids, adult rhesus monkeys have a prehensile tail the length of which averages nearly 50 percent of the monkey’s sitting height. Return to Text.
- Lin, P.J., et al., Human tail and myelomeningocele,
Pediatric Neurosurgery 43(4):334–337, July 2007,
&ArtikelNr=103318. Return to Text.
- Online Mendelian Inheritance in Man, OMIM Statistics www.ncbi.nlm.nih.gov/Omim/mimstats.html, accessed 31 August 2007. Return to Text.
- Andrews, R.C., A remarkable case of external hind limbs in a humpback whale, American Museum novitates, No. 9, 1921, digitallibrary.amnh.org/dspace/handle/2246/4849. Return to Text.
- [Popper autobiography quote.] Return to Text.
- More examples of polydactyly in Raphael’s paintings 1:274, May 2001, www.bmj.com/cgi/content/full/327/7418/E33; Polydactyly reported by Raphael , BMJ 2000;321:1622 ( 23 December, www.bmj.com/cgi/content/full/321/7276/1622. Return to Text.
- Wikipedia: Polydactyly en.wikipedia.org/wiki/Polydactyly accessed 30 August 2007. Return to Text.