Useless Body Parts

[Flamingo Girl]

From Discover magazine:


"Nearly a century and a quarter after Darwin’s death, science still can’t offer a full explanation for why one outdated anatomic trait lingers in the gene pool and another goes. Modern genomics research has revealed that our DNA carries broken genes for things that seem as though they might be useful, like odor receptors for a bloodhound’s sense of smell or enzymes that once enabled us to make our own vitamin C. In a few million years, humans may very well have shed a few more odd features. So look now before they’re gone."

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

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.

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. Our hominid ancestors lost the need for a tail before they began walking upright.

[thomas7g]

I actually would enjoy a good ear wiggle. But I'm not at all excited about producing milk.

[Flamingo Girl]

*wiggles ears and wags coccyx at Thomas*

[unowhoandwhy]

Originally Posted by Flamingo Girl

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.

These people obvioulsy haven't been to some of the beaches I have. Uggh! Gentlemen, if it looks like you're wearing a sweater and you're not, please invest in some wax or some Nair. Please?! It's not as sexy as you may think!

All joking aside, that is very interesting information, FG. Thank you!

[The 14th Colony]

I'll tell you about an extra body part that I've found is far from useless. It's the third arm that I have, growing out of the top of my shoulder. It is very usefull for scratching my back. And in the days when I had a full head of hair, shampooing took a third less time.

Only God knows why these things are so. His ways are past finding out.

[unowhoandwhy]

Originally Posted by The 14th Colony

I'll tell you about an extra body part that I've found is far from useless. It's the third arm that I have, growing out of the top of my shoulder. It is very usefull for scratching my back. And in the days when I had a full head of hair, shampooing took a third less time.

:laugh: