How Does Hair Know the Difference??

Morning Hairy!

Woah.

Say, how does your hair know to grow LONG on your head...

SCRAGGLY on your face...

And THIN everywhere else??

Well, we need to rewind to when you were just a tiny blob of cells in the womb...

Your entire body is covered in this fuzzy stuff called lanugo.

Keeping you cozy until birt–

Oh.

Wow.

You shed all that lanugo, then you–

Ya, you go through puberty.

Which is when your hair follicles get specific instructions from different hormones.

And they're wildly different depending on location.

Like head hair receptors are basically hormone-deaf:

They don't care.

But facial hair receptors? They're OBSESSED with testosterone:

And pubic hair?

No need to show..

Same story.

But arm hair?

Those receptors are "meh" about hormones.

But hang on...

Every single hair on your body contains THE EXACT SAME DNA.

So why are the hairs themselves SO different?

Well, it's all about gene expression…

Different genes get turned on and off depending on where the follicle is.

Scalp hair? Long and smooth:

Facial hair? Thick and coarse:

Arm hair? Short and fine:

But your eyebrows – ya, they'll never grow as long as your head hair.

Every hair follicle on your body is pre-programmed!

Stay Cute,
Henry & Dylan 🌈

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