Visual Evolution: Tails on Humans
was formerly www.visual-evolution.com
Atavistic structures in individual members of a species arise from a defect in the individual's genetic development. A gene may not turn on (or off) at the right time.
These abnormalities differ from vestigial organs, that are genetic holdovers from a species' ancestors. These organs (e.g. appendix) occur in all members of a species, but have lost their original functionality.
According to CECIL ADAMS:
"Still, at one point in his/her life, every human being does have a tail. Human embryos have a tail that measures about one-sixth of the size of the embryo itself. As the embryo develops into a fetus, the tail is absorbed by the growing body, but some traces remain even in adults. Occasionally, a child is born with a "soft tail," described by one embryologist as containing "no vertebrae, but blood vessels, muscles, and nerves, of the same consistency as the short tail of the Barbary ape." Modern procedures allow doctors to eliminate the tail at birth, but some children have had to learn to live with them.
Some images have been increased in size, and colorized for clarity.
Some Creationists say "Occasionally a human baby is born with a tail-like appendage and this is said to be evidence that our ancestors had tails. Actually, such rare congenital deformities are usually a type of fatty tumor having no relationship to the tail of a monkey." You have the intelligence to judge for yourself.