13. Human VestigialityAdvertisement
Not all things that look like tails are actually “true” tails. There are a number of growths or cysts that can form right on the tip of the tailbone but no modern tails have been found to have any bone tissue. They’re mostly composed of skin with fat, connective tissue, nerves, and muscle tissue. They can also be just a stub, but some babies can be born with tails 13 centimeters long. The tails aren’t strictly useless immovable structures because they have muscle tissue inside and they can actually be twitched back and forth, or even contracted into curves. Removing them is a simple operation, usually done not long after birth.
Progeria is an extremely rare genetic disorder where patients affected show symptoms of aging at a very early age. Believe it or not, the boy in the photo is 14-years-old. The disorder has a very low incidence rate, occurring in an estimated 1 per 8 million live births. Those born with progeria typically live to their mid teens and latest till their early twenties. The oldest known survivor is Birmingham-born Dean Andrews who is 21-years-old.
Neurofibromatosis is a genetic disorder of the nervous system. It primarily affects how nerve cells form and grow. It causes tumors to grow on nerves. The disorder can be passed on from parents to children, or it can happen because of a mutation in your genes. But once you have it, you can pass it along to your children. Usually, the tumors are benign, but sometimes they can become cancerous. The man in the photo has a severe case of the disorder.
Polymelia is a birth defect affecting the limbs in which the affected individual has more than the usual number of limbs. The extra limb is most commonly shrunken and/or deformed. Sometimes an embryo started as conjoined twins, but one twin degenerated completely except for one or more limbs, which end up attached to the other twin. Or sometimes there is an abnormal development of the legs in the womb where the legs become duplicated.
Necrotizing fasciitis or commonly known as the flesh-eating disease is a serious bacterial skin infection that spreads quickly and kills the body’s soft tissue. If not diagnosed and treated promptly it can become life-threatening in a short amount of time. This rare disease can be caused by more than one type of bacteria. Sometimes toxins made by these bacteria destroy the tissue they infect, causing it to die. When this happens, the infection is very serious and can result in loss of limbs or death. People who have poor immunity are most at risk for this deadly infection.
Parry–Romberg syndrome also known as progressive hemifacial atrophy is a rare disease that causes progressive shrinkage and degeneration of the tissues beneath the skin, usually on only one side of the face (hemifacial atrophy) but occasionally extending to other parts of the body. The exact cause and mechanism still remain unknown. The prevalence of the illness is higher in females and is sometimes accompanied by neurological, ocular and oral symptoms.