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MaxManus
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Why does head and body hair differ? Doesn't monkeys have the same type of hair on their head and the rest of their body?
I've never run into this, but I suppose they'll seize on any possible issue.Simon Bridge said:I tend to be cautious about this topic because creationists have been known to use "evolution does not explain human hair therefore humans were made by God".
I had asked my physician the same question a very long time ago, "Why does hair on my arm grow to a specific length, and the hair on my head keep growing?" He said that some hair on the body falls out after growing for a given period of time which is why it always seems to be a specific length. It never stops growing, it just falls out.zoobyshoe said:The difference that intrigues me is that head and beard hair grow constantly while body hair ( and eyebrows and eye lashes) stops growing at a certain length.
I think he must have been making that up on the spot. I think body hair lingers in place without growing a long time before it falls out.Q_Goest said:I had asked my physician the same question a very long time ago, "Why does hair on my arm grow to a specific length, and the hair on my head keep growing?" He said that some hair on the body falls out after growing for a given period of time which is why it always seems to be a specific length. It never stops growing, it just falls out.
I'm not sure if this is the reason, but like I said, that's what my physician told me. Maybe someone can confirm/deny?
mazinse said:this is a good topic, I used to know someone who was research this, not sure where he went this. Yeah so your head hair does different from you back and chest hair. For example a man who is going bald due to various known causes will still have a chest and back full of hair.
http://www.healthjolt.com/hair-loss/Hair grows and falls out in a continuous three-part cycle. The three parts of the hair cycle are the growth (anagen) stage, the transition (catagen) stage, and the resting (telogen) stage. The hair falls out during the resting stage, which lasts about two to three months. Fortunately, not all of the hair is in the same part of the cycle at the same time. At anyone time, only about 10% of the hair is in the resting stage. Of the approximately 100,000 hairs on the average head, it is normal to lose about 100 hairs per day.
The typical growth cycle lasts two to six years, during which time hair grows about half-an-inch per month. At the end of the growth stage it enters the transition stage, which lasts two to three weeks. During this stage, hair growth stops and the hair root shortens and shrinks. The final phase is the resting phase, when hair falls out.
So each individual has a personal maximum hair length they can achieve. There's a Chinese guy with hair 18 feet long. He's a freak. Not because he let it grow that long but because his hair's growth period is so much longer than most people's.Q_Goest said:I did a little research on this. Seems the physician I mentioned had the right idea after all. Hair grows in a 3 part cycle, and the cycle can vary depending on where on your body it grows. I remember as a kid, shaving hair off my arm (don't ask) and finding it always grew back to the same length. The reason is as the physician mentions, it follows a cycle and then falls out. Note that hair doesn't have any signals running up and down its length to tell it when its at the right length to "stop growing" so to speak, because there is no such thing as a hair that knows how long it is. Hair has no way of determining how long it is so it can't grow to a certain length and stop. Instead, it grows for a certain amount of time and stops and then falls out.
http://www.healthjolt.com/hair-loss/
Wikipedia says the same thing:
http://en.wikipedia.org/wiki/Hair_follicle
As does this paper on the topic:
http://physrev.physiology.org/content/81/1/449.full#sec-13
In Czech the word for body hair and the word for fur are the same.Simon Bridge said:How do you think head hair is different from the rest of the body? Eg. which difference are you wanting to explain?
Monkeys have different length fur on different parts of their bodies for eg - but humans don't have fur.
This may help.
http://www.scientificamerican.com/article.cfm?id=the-naked-truth-why-humans-have-no-fur
Body hair is thinner and shorter because it serves a different purpose than head hair. Head hair is meant to provide insulation and protect the scalp from the sun, while body hair has evolved to regulate body temperature and protect the skin from abrasions and UV rays. Therefore, the texture and length of body hair is adapted to fulfill these functions.
The color of hair is determined by the amount and type of melanin present in each hair follicle. Head hair typically has more eumelanin, which produces darker hair colors, while body hair has more pheomelanin, which produces lighter hair colors. This is due to differences in the expression of genes in these areas of the body.
Head hair is more resistant to damage because it has a thicker cuticle, the outermost layer of the hair shaft. This provides more protection against environmental factors like heat and chemicals. Additionally, head hair has more layers of keratin, the protein that makes up hair, making it stronger and less prone to breakage.
Body hair, like head hair, goes through different growth stages: anagen (growth phase), catagen (transition phase), and telogen (resting phase). However, the anagen phase for body hair is shorter than head hair, which is why body hair stops growing after a certain length. This is also influenced by hormones and genetics, as some individuals may have longer anagen phases for body hair.
Yes, it is normal for body and head hair to have different textures. This is due to the fact that body hair is shorter and thinner, and also because it has a different growth cycle and exposure to environmental factors. Additionally, genetics play a role in determining the texture and thickness of both body and head hair.