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  • Give me a head with hair, long beautiful hair, shining gleaming steaming flaxen waxen.

  • HAIR!

  • It's Monday, so we're answering viewer questions today, and on our Why Do We Have Warts video,

  • Saihan, Elyse, and TheGamingWookiee all had questions about hair!

  • Different types, why do some have more than others, and why do we even need it!

  • Firstly, hair is a natural part of being human.

  • We tend to associate it with our head, face, armpits, pubic regions, and legs; but it's

  • actually everywhere.

  • We like to think of ourselves as a naked ape, but we have the same number of hairs on our

  • body as a chimpanzee; or around five million hairs.

  • Before you ask, hair and fur are the same thing.

  • You and your fuzzy dog or cat all have hair made of the same stuff: keratin.

  • Your skin is made of layers -- the epidermis, then the dermis underneath.

  • In the dermis, cells are constantly dividing, and the older cells are pushed out of follicles

  • creating hair all the time.

  • On chimpanzees, hair protects skin from the sun, and provides warmth.

  • When you take into account thermoregulation, hair was a way to keep that body warmth in

  • naturally!

  • Though, in modern humans it still protects our head from the sun's rays, and allows sweat

  • to travel along hair shafts and evaporate, cooling us down, but it doesn't keep our bodies

  • warm anymore.

  • There are many different TYPES of hair.

  • Fetuses in the womb grow hair called lanugo; though it usually recedes from the body before

  • birth, it doesn't always.

  • A comforting reminder of our primate history, perhaps?

  • After birth, we humans grow soft, fine, unpigmented vellus hair all over our bodies, though thicker,

  • pigmented hair on the head, eyebrows, eyelashes, and so on, is called terminal hair.

  • During puberty, some of vellus hair transitions to terminal hair or androgen hair -- named

  • for the sex hormones that cause them.

  • On the face, and chest for men and in the armpits and pubic regions for both men and

  • women.

  • What hair you get depends a lot on your genes.

  • A 2009 Cambridge study found the genes for hair were 85 to 95 percent inherited, though

  • some can be affected by the environment.

  • Hair curls for two reasons.

  • First, an asymmetrical, or oval-shaped, follicle will force a curvy hair to emerge; circular

  • follicles produce straight hair; but a specific cellular receptor called epidermal growth

  • factor receptor regulates the growth of hair.

  • If the EGFR puts too much keratin on one side of the hair shaft as it grows, it will come

  • out curly!

  • Hair is a holdover from our ancient ancestors.

  • As we evolved, our genes mutated, and hair thinned on some parts of the body, but the

  • why in some places and not others is an evolutionary mystery!

  • Perhaps hair lessened for social interaction, to better see the eyes and face; or as we

  • became more upright and mobile evolution favored those with just enough to reduce skin-on-skin

  • friction in pubic regions and armpits; or perhaps ancient humans spent more time in

  • the water, and hair wasn't as useful there except on the exposed parts of the head.

  • Perhaps, hair remains in the pubic regions similar to eye, head, nose, and ear hair -- to

  • block dirt and other deuterium from the genitalia or to keep UV rays away from the sex organs?

  • Or maybe it allows pheromones to spread from the body for mating!

  • The Economist writes that perhaps mature women are more visibly hairless, on average, than

  • men because, at some point, hairlessness was selected by men as a sexually attractive trait;

  • a similar theory as to why human males have the largest average penis size of all primates.

  • Again, we don't exactly know.

  • What we DO know, is maintaining SOME, but not ALL body hair, may be due to parasite

  • detection.

  • A study from England's University of Sheffield found people with more body hair could detect

  • bed bugs more quickly than those with less.

  • Though by tracing the evolution of lice alongside humans, scientists determined we started trying

  • clothing on more than 170,000 years ago.

  • This was great for the cooler temperatures of the coming ice age; and when we started

  • to move from Africa into Europe.

  • More clothing, like thicker hair, means

  • more parasiteswhich is bad

  • damn, this is a hairy topic.

Give me a head with hair, long beautiful hair, shining gleaming steaming flaxen waxen.

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