i posted this on a blog a while ago. it's quite interesting
:
1.
VOMERONASAL ORGAN (VNO), or Jacobson's organ: a tiny hole on each side of the nasal bridge that is considered to be connected to nonfunctional chemical receptors. Could be all that is left from our once great ability to detect pheromones.
2.
EXTRINSIC EAR MUSCLES: These three muscles most likely made it possible for our ancestors 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.
3.
WISDOM TEETH: Early humans had to chew a lot of plants to get enough calories to survive, making another row of molars helpful, but unless you chew a lot of branches, these will eventually come out in a painful procedure. Only about 5 percent of the population has a healthy set of these third molars.
4.
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.
5.
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, exactly there where you always catch a spec of dust or debris.
6.
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.
[i've got one of these. here's an example, but it aint mine:] 
7.
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.
8.
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.
9.
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.
10.
ERECTOR PILI: Bundles of smooth muscle fibers allow animals to puff up their fur for insulation or to intimidate others. Humans retain this ability (goose bumps are the indicator) but have obviously lost most of the fur.
11.
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.
12.
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.
13.
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.
14.
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.
15.
MALE UTERUS: A remnant of an undeveloped female reproductive organ hangs off the male prostate gland.
16.
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, the other four are for holding when you slam them on a coffee table at night!
17.
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.
18.
PYRAMIDALIS MUSCLE: More than 20 percent of us lack this tiny, triangular pouch-like muscle that attaches to the pubic bone. It may be a relic from pouched marsupials.
19.
COCCYX: These fused vertebrae are all that's left of the tail that most mammals still use for balance and communication. Our hominid ancestors lost the need for a tail before they began walking upright. All they're good for now is give us painful falls on the butt.
20.
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, except to make the head lighter and to warm and moisten the air we breathe.
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