Why Does Hair Grow The Way It Does?

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All mammals have hair at some point in their lives, but none of them wear it quite like humans. Why does our hair grow where it does, and not grow where it doesn’t? How does our hair get its color? And why does it go gray and often fall out when we get older and go bald? Learn all about the science of human hair in this week’s video!
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REFERENCES:
Harding RM, Healy E, Ray AJ, et al. Evidence for Variable Selective Pressures at MC1R. American Journal of Human Genetics. 2000;66(4):1351-1361.
Randall, Valerie Anne. "Androgens and hair growth." Dermatologic therapy 21.5 (2008): 314-328.
Yablon, J. "What is the latest theory of why humans lost their body hair?." SCIENTIFIC AMERICAN 297.3 (2007): 124-124.
APA
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Опубликовано:

30 сен 2024

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Комментарии : 918

@besmart 7 лет назад

PS - Part 3 and 4 of our human ancestry series will continue next week!

@fandyus4125 7 лет назад

Yay!

@DARRAGH396 7 лет назад

It's Okay To Be Smart yay thx

@wassupharley 7 лет назад

after that, can you make a video about how bad breathing in smoke from smokers next to you is?? I am quite interested in seeing how bad it is since my nightbours smoke like 24/7 and the smoke of them is getting into my room if I have my window open.

@NickFisherman 7 лет назад

Harley .G RU-vid only lets you thumbs up a comment once, but just know I have more for ya.

@NickFisherman 7 лет назад

***** either the darker eumelanin will overwhelm the color, or it produces auburn tones.

@tvremote9394 7 лет назад

you can almost say the way your hair grows depends on your hairitage

@besmart 7 лет назад

mmhmm yes, I approve

@Kevin-um1nq 7 лет назад

It's Okay To Be Smart how dare you partake in such evil

@shivanshu38 7 лет назад

It's Okay To Be Smart Your Facts are good but your face is as annoying like sleepers..😋

@pastordonkoh7692 6 лет назад

stop the planet, I want to get off

@luciferangelica 5 лет назад

@@Kevin-um1nq what kinda evil would you prefer, silent bob?

@justmutantjed 7 лет назад

0:28 - Oh thank goodness. I was about to wig out.

@LucidDreamer54321 2 года назад

My hair? My home planet has a different form of gravitational field.

@joshuacousin3248 7 лет назад

Thank you for the jokes in this episode. Stressful day just got better

@Marshiethemarshmallow 4 года назад

Lol the thumbnail is hilarious!!!! I thought he would wear that during the video though...... 😭

@spindash64 6 лет назад

so, why do we still keep as much hair on our limbs and torso as we do? my theory is that it further increases surface area for sweat to cling to for superior cooling

@zarchocon 7 лет назад

Whats the smaller title above the main title? "How your body works! S1•E15" Is it only for videos in a playlist?

@VFXResearch254 7 лет назад

I had seen your comment on veritasium 'sun sneezer' video. I don't see your comment there anymore, you two had any discussion on it?

@GehennaGirls 7 лет назад

Missed your chance to have a picture of the rock at the end... you went with vin diesel.

@LifeTheorist 5 лет назад

I have 2 and a half feet long hair. I never got lice, probably because I am seriously careful about my hair. I love my hair.

@frenchrev.2379 2 года назад

I'm sticking with the story that we decided gorillas were niiiice just cause I think it's funny

@justwhatever1747 5 лет назад

What if you have black brown hair and then have the occasional strands of blonde hair popping up?

@donteyeballme3161 7 лет назад

now that's punny

@andeh900 7 лет назад

PBS Studios? I bet the PBS stands for Pun Based Science

@moomoomoomuu 7 лет назад

@wj9855 6 лет назад

Exactly

@partyboik1458 6 лет назад

no its a chanel called pbs

@lncerante 6 лет назад

It stands for pubis!

@josephinestalime3094 5 лет назад

Yep

@ispilloil 5 лет назад

Guys: History Girls: Herstory Joe: *_h a i r s t o r y_*

@anujarora0 3 года назад

100th liker baby

@asitkumarray7720 3 года назад

OMGALUL

@rishabhanand5563 3 года назад

This is underrated😂😂

@AbudBakri 7 лет назад

Lost a couple hairs while watching this. *help*

@daksh8747 7 лет назад

Are you a bot?

@AbudBakri 7 лет назад

I am C3PO, human cyborg relations.

@pseudo.Random-KF 7 лет назад

cut it guys

@luciferangelica 5 лет назад

@@AbudBakri human/cyborg, all male, sexual relations

@besmart 7 лет назад

Sure, the science is interesting, but think you can beat my hair puns? Go ahead and try!

@daksh8747 7 лет назад

Wait the video was released 30 seconds ago and your comment is 32 minutes old What?!

@Mokilglp 7 лет назад

It's Okay To Be Smart you really missed a pun with the rock at the end. still a great video though!

@AbudBakri 7 лет назад

Daksh Joshi - you can upload to private first

@fandyus4125 7 лет назад

I would tell some chemistry puns, but all the good ones argon.

@fandyus4125 7 лет назад

Also don't believe atoms, they make up everything.

@AboveTheNoise 7 лет назад

Very cool video. Great to learn why the carpet doesn't always match the drapes -- just wish we didn't watch it during lunch (very vivid pubic lice animation).

@delilahdude3041 6 лет назад

@tadi7847 6 лет назад

You didn't really answer the question in the title.

@birthgravy 5 лет назад

He touched on it for a bit

@אורליי-ג1ס 5 лет назад

Didn't answer at all! I'm really puzzled about how long hair can be beneficial to us in any way. Why doesn't it just stop growing at a certain lengh like our eyebrows or pubic hair? Same for our fingernails - if you don't cut them they become curly and disturb the functioning of your hands alltogether.

@zema9401 5 лет назад

It helped finding a mate such as male peacocks dont have any survival advantages having long as, fabulous feathers. Thats just a guess, though.

@travisgrant5608 5 лет назад

Yes they did ... pay attention!

@DarkGodSeti 5 лет назад

Still interesting. But yea... To me, it was more about ' Why does the hair on our heads grow indefinitely?'. So I just googled it afterwards... haha

@vaughneudy3003 2 года назад

From an evolutionary standpoint, it seems we kept the hair on our heads despite losing it almost everywhere else because hair is a good indication of health. Most dermatologists will tell you the best treatment for hair is eating well. So people with good hair attracted mates and passed the traits on.

@TiffanyHallmark 7 лет назад

This was great! I'm a hairdresser and it's lovely to see the topic presented. Did you know that all natural redheads have greenish ashy color to their hair? That's why it's difficult to artificially create a "natural" redhead.

@stillhere1425 2 года назад

In old-school color photographs and on not terrific color television pictures, redheads often seemed to have a sort of dull green patina to their hair rather than a copper or bronze gleam. I had auburn hair that frequently appeared muddy and greenish in photographs. Now you have explained why.

@Trund27 2 года назад

That’s so interesting!!

@royalfelineandtracygrant 8 месяцев назад

Quite interesting!

@grinsekatze3085 5 лет назад

"That's why the carpet doesn't always match the drapes" LMAO 😂😂😂😂😂😂😂

@kimia1664 3 года назад

My big hair question is why is head hair capable of growing with no boundaries but body hair stays the same height?

@akshitrajput757 6 лет назад

4:14 A bald scientist figuring out how to stop hair loss... Haha

@YathishShamaraj 3 года назад

😁😁😂 I guess need is the mother of invention 😉👍

@designermombygeetachugh2022 3 года назад

Haha.. Didn't notice that while watching the video

@russ4550 6 лет назад

Cmon man step up your game you only told us why about pit hair you didn't say why we have head hair or pubes and you didn't say why we don't have hair in others places (except when you made the slight mention of "maybe we got rid of some to shed heat" and that's as far as you went...)

@gipen 6 лет назад

I downvoted for this ^ reason

@maxvarjagen9810 6 лет назад

Hair is portable shade, protects us against sunburn. We stand upright, so long hair on our head gives most of the body cover. Pubes protect the more sensitive areas. We got rid of the rest because we evolved in africa and it was hot enough already.

@laurapirate 6 лет назад

I think pubes are to prevent friction during sex,and on women they actually prevent harmful bacteria from going in the vagina.

@Wingedwolfstar67 5 лет назад

I also wanted to know why our hair doesn’t stop growing at a certain length in some places but not others. Example, why does the hair on your arm only grow so long but hair on your hair doesn’t stop growing

@StephJ0seph 5 лет назад

It's because we don't really know lol... I think that he's just trying to strike up the conversation.

@emmaabadeer9107 6 лет назад

You didn't really answer why, I feel like a lot more could be said for another video.

@torugho 5 лет назад

ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rf6BnOLb5xs.html here's a way better video about this

@maggie1000 5 лет назад

Thirsty Leaf That video doesn’t answer the question either. It just explain how hair grows

@cube2fox 4 года назад

The interesting questions are: - Why did we lose most hair when we became human? - Why _didn't_ we lose head hair & pubic hair? Bonus: - Why do some male people grow beards while others don't?

@lonestarr1490 3 года назад

@@cube2fox In order of appearance: - We didn't. As said in the video, we still have about the same amount of follicles we always had. It's just not growing into dense fur anymore, probably due to evolutionary advantages this change yields. Sweat works best without fur. - Because losing head hair didn't yield the same advantage. Plus head hair protects your brain from UV radiation to some extent, while pubic hair helps holding your scent presumably making you more attractive to the other sex (in the olden days). - Genetics. And yeah, it bothers me as well.

@cube2fox 3 года назад

@@lonestarr1490 That's a good attempt. Of course we lost the fur because this was advantageous. Otherwise we wouldn't have lost it. But why was it advantageous? If it was because we could sweat more, why was sweating more more advantageous than having fur? Most other mammals still have their fur. Sweating can't be better _per se._ Regarding UV radiation. That's an interesting theory. But why would the head be more impacted by UV radiation? It seems skin on other parts of the body are equally damaged by sunburn. Regarding beards, "it's genetic" isn't really an argument. Of course it's genetic that e.g. Indians and East Asians don't grow much beards while Europeans are the opposite. But why the difference? Why beards at all? And why don't woman have beards?

@RobinGlitter 5 лет назад

You didn’t really answer the question at all?? The whole history of hair thing was interesting, but you didn’t say why humans grow hair the way we do.

@birthgravy 5 лет назад

Yeah he did lol

@diegovazquez2714 5 лет назад

neberyx when? Because I never heard him give an actual reason of WHY it only grows where it grows. I only heard him explain WHEN it stopped growing as thick as other apes hair and why it is the color that it is.

@testedalexthegreat1759 4 года назад

@@diegovazquez2714 1:01 also, we evolved sweat.

@RickMason-yj7pv 4 года назад

Vanity. Otherwise it would look like a cootie nest.

@i_am_ironman3380 3 года назад

Nothing about why some people have wooly hair while others have it straiter

@Bersekro 7 лет назад

One of the best Science RU-vid Channel's ever! Keep posting. Stay Curious. Cheers from a Brazilian Fan

@Sergio-fu7mv 4 года назад

Why is my last name so popular in Brazil?

@lonestarr1490 3 года назад

@@Sergio-fu7mv Because one of your ancestors couldn't keep it in his pants.

@justcallmekai1554 3 года назад

@@lonestarr1490 Lmao

@melinapiccolo3526 7 лет назад

sooo it's a hairy situation?

@calebvonweichardt7785 6 лет назад

Doctor, Doctor! My hairs falling out, Can you give me something to keep it in? Sure! Here's a shoe box!

@Etaukan 7 лет назад

Still waiting for Science to fix that hair loss problem. Stiiiiiillllllll waiting. .................waiting. ..............................just over here. Waiting. ............................... .........................Seriously, any time now, guys.

@nootnoot1463 7 лет назад

Etaukan I'll do it. Just give us a min

@Etaukan 7 лет назад

Ah, great, finally!

@feynstein1004 7 лет назад

Get a hair transplant, mate. It's the only lasting solution. No pun intended.

@arabtrooper3929 7 лет назад

Comb down with the buns guys.

@lizak7323 5 лет назад

You made me smile HUGELY from inside thx 😊, I don't have dep ression btw

@richgg2 6 лет назад

I love your videos! Not to long, not to short, just right! And so informative and interesting! I freaking love it! Please keep pumping them out! I'm your number one fan!

@vignesh0208 4 года назад

We switched our Fig leaves for "leather" jackets. I see what you Did there. :)

@canyounot2102 6 лет назад

Is it just me bad his puns are so bad they’re actually hilarious?! Oh my god I love this guy

@TheReligiousAtheists 7 лет назад

Am I the only one who realized that louse is the singular of lice after watching this?

@awesomeness9824 7 лет назад

let's brush the hair puns aside and cut to the point (of the blade)

@Tharkon 4 года назад

Lost most of our long hair so we can sweat and lose heat without having to stop running. I get that, but I never really figured out why we didn't lose all our long hairs. My theory is that the brain is too precious to leave naked and cold, and pubic hair helps protect against a lot of diseases.And I suppose both pubic and armpit hair is less exposed while running so there is less to gain from losing those hairs compared to others. But what about beards, and why only men? Is it something similar to Dothraki ponytails? Also, I still think it's a shame that your tagline isn't simply "Remember, it's okay to be smart."

@XWierdThingsHappenX Год назад

It could all so be that people simply found hair on the head attractive. It's part of our culture today. I dont see why it wouldn't be part of our ancient ancestors culture.

@Eyeamthewitness Год назад

Maybe evolution in this sense isn’t real?

@meggriffin7401 7 лет назад

I have a question if anyone can answer that's fine. Both my parents had blonde hair when they were born, but it started to get darker and turn to brown as they grew up. My brother and I also have that happening to us. Anyone able to explain this?

@darllington8995 7 лет назад

Kitkatgriffin Loves cookies also curious

@alexjordan8838 7 лет назад

Meg Griffin ok no one get angry if this is wrong it's just a guess. I know that hair texture can change during puberty, and that is also inherited. So it may be that different hormones change that when your hormones in general change

@ghada848 7 лет назад

In very broad terms, it's about the way DNA works. blond hair means that there is a low concentration of dye being produced, meaning that the genes responsible for producing dye are not activated, but those genes can be activated later in life with a certain kind of protein called a transcription factor (TF). sort of the opposite of what happens with the ability to digest milk using lactase. Mammals lose the ability to digest milk as they grow older, Because they lose the ability to make lactase as their lactase gene is turned off.

@vladimirvilliani6732 6 лет назад

You were so busy making hair puns that you forgot to answer the question, genius.

@1019wc1019 7 лет назад

You mentioned pheromones excreted by humans but I remember an episode of scishow saying there wasnt any evidence that humans had pheromones

@CrouchingGoatHiddenDonkey 7 лет назад

There's been studies that showed brain activity based on odors from clothing of the opposite sex. Problem is, no one knows where pheromones are absorbed; no evidence of receptors in the nose. Since we can't find evidence of something, it's kind of ignored or doesn't exist. After all, if you publish a paper today that states humans react (sexually) to pheromones of the opposite sex based on brain activity MRIs, but can't show the chain of events that led to this reaction, you haven't really done proper science.

@1019wc1019 7 лет назад

Its okay to be smart

@besmart 7 лет назад

In addition to what Crouching Goat, Hidden Donkey said, there have been behavioral psychology studies showing that people have preferences for certain bodily odors on clothing in blind studies, so there's some factor in apocrine body odor that can invoke *feelings* even though we don't know what it is. Call it pheromones, call it sexy BO… whatever. It's a mysterious but probably real thing.

@1019wc1019 7 лет назад

Thanks for the response. I wanted to be snarky about it ;) And yea female BO is a different chemical make up right?

@feynstein1004 7 лет назад

Glad I'm not the one who noticed that.

@h.s.manjunathahossur398 4 года назад

Mixing humour with science may entertain, but can also confuse sometimes.

@dejanamarkova6460 7 лет назад

i love the puns

@skylerjayy9956 5 лет назад

What about our eyebrows? I’ve always wondered why so bushy just above the eyes none in the middle (for most people) and why doesn’t it go all the way up to our hairline?

@b-init1221 4 года назад

Anything: Exists This Guy: *"Why do you exist huh? What's your aim in life?"*

@sciencenerd7639 Год назад

Joe Hansen worked in puns the way other artists might work in oils or clay. It was his true medium. A master.

@thelastcube. 7 лет назад

SCIENCE IS AWESOME!!!

@pauljones3017 7 лет назад

Indeed!

@johnarbuckle2619 7 лет назад

Chaitanya Singh You said it yourself oldtimer

@alex-fs9yt 5 лет назад

That thumbnail though😂

@rogersledz6793 3 года назад

Thank you so much for uploading this video. It is helping me get through the pandemic!

@lyubaalexeievnapetrova9373 7 лет назад

Love these science videos!

@terrykrow7820 5 лет назад

You didnt answer why we have thick hair just on our heads...

@nadagligorin9947 7 лет назад

I like the way you make the science fanny! Keep on the good work.

@arslaan2001 6 лет назад

I love watching your videos full of unique knowledge I can't get any where except here

@saquist 7 лет назад

Don't ever do a video on Gender Fluidity...please. I'll have to cut you off man. Nothing personal....stay Texan!

@thelastcube. 7 лет назад

JUST SAW SCISHOW'S VIDEO ON WHISKERS.... MMM TODAY'S A VERY HAIRY DAY

@thelastcube. 7 лет назад

LagiNaLangAko23 Lol

@sciblastofficial9833 7 лет назад

Chaitanya Singh Cruel, your profile picture makes people clean the screen

@paarthwardhan1263 4 года назад

I observe one thing that I caught my beard coming when I was 15 but the people who are native to other countries, some got late and some get more early than me. Therefore, there must be variation according to the countries to which the person belongs.

@gallantcp 7 лет назад

0:40 A Surprise Kyle Hill has appeared

@Aeturnalis 3 года назад

I used to make fun of my friend in highschool because his parents were from England and they both had British-pattern baldness. He had thick, long hair at the time, so I told him if he wanted to keep his hair, he should get a shoebox lol he insisted he'd never lose his hair, but the genetics in this one is strong, and he was bald as polished egg by 23. He didn't look cool like the Rock or Vin Diesel, he looked sad like the lawyer from scrubs lol

@Phlegethon 4 года назад

I’m using covid as my excuse to grow my hair out already did mustache

@trebor1048 7 лет назад

Somewhat first

@Leme994 6 лет назад

great video! But I came to this video because I wanted to know the reason we only have long hair in our heads. Maybe we used to use our hair as a water filter when drinking water form, let's say, a waterfall or any other source in which the water comes from above. It would prevent some of the bigger particles in the water when we drank water that's passing through it, wouldn't it?

@susannahayres-thomas7185 7 лет назад

What I want to know is this. Before I had cancer, I had hair that was straight as a stick. But after kemotherapy for that cancer, my hair fell out, yes, ALL of it. But when it grew back, it grew curly--and still is. So, WHY! Dr Joe, why? Oh, I like it curly, but I still want to know why the difference...

@noirettebeauty 4 года назад

I still haven’t figured out the evolutionary purpose for the hair growing from my husband’s butt cleft😔😔😔

@9rumpole 7 лет назад

notification squad

@davidjacobs8558 5 лет назад

no apes or monkeys have long hair on their head. man and woman both have long hairs growing out of their head, and obivously this trait developed after ancestors of humans started walking up right.

@DARRAGH396 7 лет назад

First To be last

@hadharam 7 лет назад

Omg I dont think any other youtube channel has videos of better quality you guys are amazing

@gabrielfenechazzopardi7965 7 лет назад

D puns m8

@quantumpuddles7591 6 лет назад

Wait. Why is albino hair pure white and non-albino hair that has no pigment grey? They both don't have melanin so shouldn't they be the same color.

@dhananjaykrishnan6210 6 лет назад

GO MELANIN

@bananasrotatebananarotatof5423 3 года назад

Thank you for the video but I have a question still non answered, why do hair (head hair) grow long while others don't?

@good_8 7 лет назад

wtf

@switchdude5854 7 лет назад

I really like your vids and it's amazing what I learn from you and others on RU-vid

@helenzracova3072 7 лет назад

I really like argan rain products . the product changed my life. It is stimulating new hair growth, I will continue to use it. The best shampoo is argan rain anymore for me.

@gyozakeynsianism 6 лет назад

Why are people so mean to Vin Diesel? So mean. He's a nice guy. He is not a Neanderthal. I'm pretty sure anyway.

@williamallman299 7 лет назад

Another good video, I learned a couple things I didn't know (pigmentation mix, where lice came from), but you did miss one point.....that humans are still covered with hair, even females, it's just much finer and not very noticeable (usually), and that we lose about 100 hairs a day overall. :-)

@torugho 5 лет назад

For anyone actually wanting the answer to the question: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rf6BnOLb5xs.html

@tracesprite6078 2 года назад

I think my grey hair has become thicker since I've been rinsing it in cold water after washing it in warm water.

@thuyvienthi8036 3 года назад

0:40 like Tzuyu (TWICE) archery moment in Issac 2016

@jameswallace9906 5 лет назад

Thumb nail says “why do we grow hair” Wtf I know this Why do I have back mane dammit!! 🤨

@aymanghazali9551 6 лет назад

What would happen if i pull out a strand of hair? Would the angle of follicle change too?

@PaiviProject 6 лет назад

Hello. You are just so entertaining and I learn at the same time. I did not know this. Thanks 👍

@lolscience1979 5 лет назад

27 sec in and already to many puns for my brain to handle!

@coffeefrog 7 лет назад

I didn't know that hair comes curly or straight because of that. How cool!

@gnuling296 4 года назад

Excellent video. Didn't expect to understand two important things just a minute in.

@florence1241 4 года назад

I- No one's talking about the thumbnail.

@elimalinsky7069 5 лет назад

A wonderful coarse indeed, I've bun waiting for this. Not a bald statement at all, it inspires my curliousity. I was braid fur this kind of stuff. You could say I'm locky.