The Volokh Conspiracy - Top 10 Signs Of Evolution In Modern Man:

The List Universe offers 10 signs of evolution in our bodies, with some nice accompanying graphics. (hat tip LGF):

Through history, as natural selection played its part in the development of modern man, many of the useful functions and parts of the human body become unnecessary. What is most fascinating is that many of these parts of the body still remain in some form so we can see the progress of evolution. This list covers the ten most significant evolutionary changes that have taken place - leaving signs behind them.

Here are a few:

10. Goose Bumps: Humans get goose bumps when they are cold, frightened, angry, or in awe. Many other creatures get goose bumps for the same reason, for example this is why a cat or dog’s hair stands on end and the cause behind a porcupine’s quills raising. In cold situations, the rising hair traps air between the hairs and skin, creating insulation and warmth. In response to fear, goose bumps make an animal appear larger - hopefully scaring away the enemy. Humans no longer benefit from goose bumps and they are simply left over from our past when we were not clothed and needed to scare our own natural enemies. Natural selection removed the thick hair but left behind the mechanism for controlling it. . . .

6. Plantaris Muscle: The plantaris muscle is used by animals in gripping and manipulating objects with their feet - something you see with apes who seem to be able to use their feet as well as their hands. Humans have this muscle as well, but it is now so underdeveloped that it is often taken out by doctors when they need tissue for reconstruction in other parts of the body. The muscle is so unimportant to the human body that 9% of humans are now born without it. . . .

3. Darwin’s Point. Darwin’s point is found in the majority of mammals, and humans are no exception. It is most likely used to help focus sounds in animals, but it no longer has a function in humans. Only 10.4% of the human population still has this visible left-over mark of our past, but it is possible that a much larger number of people carry the gene that produces it as it does not always cause the ear tubercle to appear. The point (shown in the picture above) is a small thick nodule at the junction of the upper and middle sections of the ear.

For some reason, I found that the fact I am one of the 10.4% who have this feature to be somewhat creepy.

Also, it turns out that, just recently, scientists think they may have discovered a function for #1 on the list: the appendix (so maybe there is still hope for Darwin's Point). Tech News Watch blog reported that Appendix Isn’t Useless At All: It’s A Safe House For Bacteria:

Long denigrated as vestigial or useless, the appendix now appears to have a reason to be — as a "safe house" for the beneficial bacteria living in the human gut.

Drawing upon a series of observations and experiments, Duke University Medical Center investigators postulate that the beneficial bacteria in the appendix that aid digestion can ride out a bout of diarrhea that completely evacuates the intestines and emerge afterwards to repopulate the gut. Their theory appears online in the Journal of Theoretical Biology.

"While there is no smoking gun, the abundance of circumstantial evidence makes a strong case for the role of the appendix as a place where the good bacteria can live safe and undisturbed until they are needed," said William Parker, Ph.D., assistant professor of experimental surgery, who conducted the analysis in collaboration with R. Randal Bollinger, M.D., Ph.D., Duke professor emeritus in general surgery.

The appendix is a slender two- to four-inch pouch located near the juncture of the large and small intestines. While its exact function in humans has been debated by physicians, it is known that there is immune system tissue in the appendix.

The gut is populated with different microbes that help the digestive system break down the foods we eat. In return, the gut provides nourishment and safety to the bacteria. Parker now believes that the immune system cells found in the appendix are there to protect, rather than harm, the good bacteria.

Read the whole thing if you have the stomach for it. I think I will now watch Orin's video of the speeder again.

	[Randy Barnett, January 14, 2009 at 12:05am] Trackbacks Top 10 Signs Of Evolution In Modern Man: The List Universe offers 10 signs of evolution in our bodies, with some nice accompanying graphics. (hat tip LGF): Through history, as natural selection played its part in the development of modern man, many of the useful functions and parts of the human body become unnecessary. What is most fascinating is that many of these parts of the body still remain in some form so we can see the progress of evolution. This list covers the ten most significant evolutionary changes that have taken place - leaving signs behind them. Here are a few: 10. Goose Bumps: Humans get goose bumps when they are cold, frightened, angry, or in awe. Many other creatures get goose bumps for the same reason, for example this is why a cat or dog’s hair stands on end and the cause behind a porcupine’s quills raising. In cold situations, the rising hair traps air between the hairs and skin, creating insulation and warmth. In response to fear, goose bumps make an animal appear larger - hopefully scaring away the enemy. Humans no longer benefit from goose bumps and they are simply left over from our past when we were not clothed and needed to scare our own natural enemies. Natural selection removed the thick hair but left behind the mechanism for controlling it. . . . 6. Plantaris Muscle: The plantaris muscle is used by animals in gripping and manipulating objects with their feet - something you see with apes who seem to be able to use their feet as well as their hands. Humans have this muscle as well, but it is now so underdeveloped that it is often taken out by doctors when they need tissue for reconstruction in other parts of the body. The muscle is so unimportant to the human body that 9% of humans are now born without it. . . . 3. Darwin’s Point. Darwin’s point is found in the majority of mammals, and humans are no exception. It is most likely used to help focus sounds in animals, but it no longer has a function in humans. Only 10.4% of the human population still has this visible left-over mark of our past, but it is possible that a much larger number of people carry the gene that produces it as it does not always cause the ear tubercle to appear. The point (shown in the picture above) is a small thick nodule at the junction of the upper and middle sections of the ear. For some reason, I found that the fact I am one of the 10.4% who have this feature to be somewhat creepy. Also, it turns out that, just recently, scientists think they may have discovered a function for #1 on the list: the appendix (so maybe there is still hope for Darwin's Point). Tech News Watch blog reported that Appendix Isn’t Useless At All: It’s A Safe House For Bacteria: Long denigrated as vestigial or useless, the appendix now appears to have a reason to be — as a "safe house" for the beneficial bacteria living in the human gut. Drawing upon a series of observations and experiments, Duke University Medical Center investigators postulate that the beneficial bacteria in the appendix that aid digestion can ride out a bout of diarrhea that completely evacuates the intestines and emerge afterwards to repopulate the gut. Their theory appears online in the Journal of Theoretical Biology. "While there is no smoking gun, the abundance of circumstantial evidence makes a strong case for the role of the appendix as a place where the good bacteria can live safe and undisturbed until they are needed," said William Parker, Ph.D., assistant professor of experimental surgery, who conducted the analysis in collaboration with R. Randal Bollinger, M.D., Ph.D., Duke professor emeritus in general surgery. The appendix is a slender two- to four-inch pouch located near the juncture of the large and small intestines. While its exact function in humans has been debated by physicians, it is known that there is immune system tissue in the appendix. The gut is populated with different microbes that help the digestive system break down the foods we eat. In return, the gut provides nourishment and safety to the bacteria. Parker now believes that the immune system cells found in the appendix are there to protect, rather than harm, the good bacteria. Read the whole thing if you have the stomach for it. I think I will now watch Orin's video of the speeder again.