4. Only humans get acne. Here is why

Doctor Jacob here today, and we're going to talk about "Only humans get acne. Here is why." Basically that's a true statement - only humans get acne. There are a bunch of factors in humans that are unique to humans, such as wearing make-up and drinking milk [as an adult], and these may contribute to acne, but there's a certain fundamental property of human skin which is very unique to humans which predisposes us to acne, and we're going to explore that.

First, let's talk in brief about why acne comes about. Acne starts as a clogged pore which can then progress to a pimple or a pus-filled pimple, and a nodule or a cyst. But acne always starts out as a clogged pore. Pore is another word for hair follicle.

Now, inside a hair follicle there are a couple of structures. One is a hair, and in humans the hair is small, as compared to, let's say, other members of the primate family. There are also other structures besides hairs inside hair follicles or pores, and those are the oil glands. Oil is generally meant to lubricate the hair and is secreted by the oil glands or sebaceous glands onto the hair. In the scientific language it's called sebum. Sebum is a complex mixture of oils secreted by the sebaceous glands, meant to lubricate the hairs. If you imagine, the hairs are kind of like a wick on a candle. The wick, or the hair, helps make the sebum kind of leave the follicle and go up the shaft of the hair to lubricate it.

In humans, the hairs in many places, for example the forehead and the nose, are very small and fine. When compared to our ancestors from which we evolved, other primates, the hairs are so fine that the oil is not allowed to travel fully up the hair, and kind of gets retained within the hair follicles. Therefore, almost every population around the world has this predisposition to getting acne, especially during the teenage years, where the hormones activate the sebaceous glands.

So the primary reason why only humans get acne is that we have big sebaceous glands or oil glands, and relatively small, or sometimes diminutive, dwarf hairs in our follicles (miniature hairs).

At least by comparison to our ancestors of other primates, there are certain things that are also unique to humans that make acne worse, for example we can eat sugary diets, or we can wash our face with soap that destroys the natural bacteria on the face, or we have more chronic stress than many other animals, which can flare acne. Or we can put things like sun block or makeup onto the face, which can block the pores even further. Or we can even use thick hair conditioners that can then fall down onto the forehead and block the pores there. These are other uniquely human things, but the substance of the pore itself, the fact that we have very large oil glands and only tiny - relatively speaking - hair follicles, that's what predisposes humans primarily to getting acne.

That does it for this episode. See you next time!