I think vestigial organs are so cool. The idea that body structures that were once useful and are no longer needed but haven't quite been selected out yet is fascinating. Like the appendix, wisdom teeth, or fetal tails. Or how horses have traces of phalanges buried by their leg bones, because they're descended from an animal with paws before they evolved hooves.
I heard from someone a while ago that because human pinky fingers are used so little in comparison to the first two fingers and thumb, that over generations the bones are starting to shrink. Eventually, the theory goes, we will only have vestigial traces of a pinky finger.
Thing is, I don't think that's enough evolutionary time, considering how huge the human population is and the lack of selection pressures regarding the presence of fingers... I mean, it's not a matter of life or death whether or not you have a pinky! And unless you believe in Lamarckian evolution en.wikipedia.org/wiki/Jean-Baptiste_Lamarck it shouldn't be possible for humans to force an adaptation like that.
What do you think? What is the significance of pinkies? Vestigial organs in general? Have any favorite vestigial organs or other examples? Does anyone have exceptionally small pinkies or whatever that could possibly prove that theory? Has anyone else HEARD about the Case of the Shrinking Human Pinky Fingers, or was someone just making shit up?
My understanding of evolution is that use doesn't matter per say. It's who lives longer/ breeds more. In this day of age I don't see why someone with a missing pinkie would be more likely to produce more offspring than a person with a pinkie intact. Same issue with pinkie size.
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.
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. This just makes me angry; I’ve been spending a fortune on milk all these years! I’ll have to test this tomorrow with my Special K.
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.
"When you get sad, Stop being sad, And be awesome instead!"
Awesome. Thanks! I didn't know about most of those, like the muscles or... female... sperm ducts... So thanks for that.
The thing about body hair is pretty facsinating - I heard in my biological anthropology class (the sex one) that thicker, darker facial and body hair tends to be more attractive to women because it signifies higher levels of testosterone.
I tend to think body hair is pretty unattractive, though. Don't know what that says about me. O.o
I don't care for body hair, either. I like long hair on the head, but a lot of hair anywhere else just isn't that appealling to me. Interestingly enough, I've heard that men go bald on their heads from a high level of testosterone, though this may be just pop culture talking. lol. I think the fact that not all of us have all the vestigial organs is what is the most interesting. It seems to me that it shows that different groups of people developed at different times and in different ways based on their environment, though I'd like to have more statistics on this before I go forming a solid conclusion. Another interesting thing is the Jacobson's organ. It is present and highly developed in modern day reptiles. They bring in the chemicals on their tongue and to that organ, and the chemicals send electrical impluses to the brain that give it an understanding of its environment.
The fact that humans have it but it is now useless is fascinating to me. But then again, whales have remnants of hind leg bones and toes. It's pretty amazing when you think about it.
I just found out that one of my friends has a SECOND set of wisdom teeth that are coming in. She had her first four wisdom teeth removed several years ago, and now she has another four wisdom teeth coming in that need to be yanked out.
I don't know. I'm thinking that having an entire extra set of teeth would be a genetic fluke of a mutation instead of something marking an evolutionary advantage. Like, whatever gene determining the number of teeth got copied twice, or some other twist of chance.
I bet that person's mouth was really crowded. Before I got braces when I was younger, I had to have seven teeth yanked out because there wasn't enough room in my mouth for even a NORMAL amount of teeth... In fact, one of those seven yanked teeth was actually one of my front incisors. My mouth was so crowded that my teeth bumped into each other as they were growing, and the roots of that tooth got ground down until it couldn't stay in much longer. Sucked to have a huge gap in the front of my mouth (especially during those insecure times).