Here’s a partial list of some of the vestigial/useless organs found in humans today. These features are evidence that we did not descend from demigods nor are we the product of a perfect independent creation but rather, that we evolved from a long unbroken chain of species going back billions of years.
Our bodies are littered with parts we don’t need. Some are vanishing leftovers from our prehominid ancestors, such as muscles useful for walking on all fours or hanging from trees that appear in various atrophied forms. Others are by-products of a natural redundancy inherent in human sexual development, including nipples on men and the tiny vestigial sperm ducts lurking behind the ovaries of women. Then there are curiosities that, having outlived their apparent usefulness, linger simply because there’s no real reason to leave: What good or bad is hair on the little toe—or even the little toe itself?
PARANASAL SINUSES: The nasal sinuses of our early ancestors may have been lined with odor receptors that gave a heightened sense of smell, which aided survival. No one knows why we retain these perhaps troublesome mucus-lined cavities that sometimes fill up with mucus and must be painfully drained by drilling into the bone.
VOMERONASAL ORGAN: A tiny pit on each side of the septum is lined with nonfunctioning chemoreceptors. They may be all that remains of a once extensive pheromone-detecting ability.
EXTRINSIC EAR MUSCLES: This trio of muscles most likely made it possible for prehominids to move their ears independently of their heads, as rabbits and dogs do. We still have them, which is why most people can learn to wiggle their ears.
WISDOM TEETH: Early humans had to chew a lot of plants to get enough calories to survive, making another row of molars helpful. Only about 5 percent of the population has a healthy set of these third molars.
NECK RIB: A set of cervical ribs—possibly leftovers from the age of reptiles—still appear in less than 1 percent of the population. They often cause nerve and artery problems.
THIRD EYELID: A common ancestor of birds and mammals may have had a membrane for protecting the eye and sweeping out debris. Humans retain only a tiny fold in the inner corner of the eye.
DARWIN’S POINT : A small folded point of skin toward the top of each ear is occasionally found in modern humans. It may be a remnant of a larger shape that helped focus distant sounds.
SUBCLAVIUS MUSCLE : This small muscle stretching under the shoulder from the first rib to the collarbone would be useful if humans still walked on all fours. Some people have one, some have none, and a few have two.
PALMARIS MUSCLE : This long, narrow muscle runs from the elbow to the wrist and is missing in 11 percent of modern humans. It may once have been important for hanging and climbing. Surgeons harvest it for reconstructive surgery.
MALE NIPPLES : Lactiferous ducts form well before testosterone causes sex differentiation in a fetus. Men have mammary tissue that can be stimulated to produce milk.
ERECTOR PILI : the tiny muscles that attach to the base of each body hair. When they contract, the hairs stand up, giving us “goose bumps”—so called because of their resemblance to the skin of a plucked goose. Goose bumps and the muscles that make them serve no useful function, at least in humans. In other mammals, however, they raise the fur for insulation when it’s cold, and cause the animal to look larger when it’s making or receiving threats. Think of a cat, whose fur bushes out when it’s cold or angry. Our vestigial goose bumps are produced by exactly the same stimuli—cold or a rush of adrenaline.
APPENDIX : This narrow, muscular tube attached to the large intestine served as a special area to digest cellulose when the human diet consisted more of plant matter than animal protein. It also produces some white blood cells. Annually, more than 300,000 Americans have an appendectomy.
BODY HAIR : Brows help keep sweat from the eyes, and male facial hair may play a role in sexual selection, but apparently most of the hair left on the human body serves no function.
PLANTARIS MUSCLE : Often mistaken for a nerve by freshman medical students, the muscle was useful to other primates for grasping with their feet. It has disappeared altogether in 9 percent of the population.
THIRTEENTH RIB : Our closest cousins, chimpanzees and gorillas, have an extra set of ribs. Most of us have 12, but 8 percent of adults have the extras.
MALE UTERUS: A remnant of an undeveloped female reproductive organ hangs off the male prostate gland.
FIFTH TOE : Lesser apes use all their toes for grasping or clinging to branches. Humans need mainly the big toe for balance while walking upright.
FEMALE VAS DEFERENS : What might become sperm ducts in males become the epoophoron in females, a cluster of useless dead-end tubules near the ovaries.
PYRAMIDALIS MUSCLE : More than 20 percent of us lack this tiny, triangular pouchlike muscle that attaches to the pubic bone. It may be a relic from pouched marsupials.
COCCYX : These fused vertebrae are all that’s left of the tail that most mammals still use for balance and communication. It still has a function (some useful muscles attach to it), but remember that its vestigiality is diagnosed not by its usefulness but because it no longer has the function for which it originally evolved. Tellingly, some humans have a rudimentary tail muscle (the “extensor coccygis”), identical to the one that moves the tails of monkeys and other mammals. It still attaches to our coccyx, but since the bones can’t move, the muscle is useless. You may have one and not even know it.
Vestigial traits make sense only in the light of evolution. Sometimes useful, but often not, they’re exactly what we’d expect to find if natural selection gradually eliminated useless features or refashioned them into new, more adaptive ones. Tiny, nonfunctional wings, a dangerous appendix, eyes that can’t see, and silly ear muscles simply don’t make sense if you think that species were specially created.
Godwin’s law (also known as Godwin’s Rule of Nazi Analogies or Godwin’s Law of Nazi Analogies) is a humorous observation made by Mike Godwin in 1989 which has become an Internet adage. It states: “As an online discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches 1.” In other words, Godwin put forth the sarcastic observation that, given enough time, all online discussions—regardless of topic or scope—inevitably end up being about Hitler and the Nazis. (via Christian Dobre)