Hello everyone, Julian here for DNews.

Nipples: everybody has them, but you probably don’t pay them much attention.

That is unless you’re cold, aroused, or talking about science

and your little bosom buddies decide to stand at attention for all the world to see.

How do nipples get hard, and what purpose does this serve?

Answering the how is a bit easier than answering the why, especially thanks to a recent study published in Nature Neuroscience.

Researchers were interested in the sympathetic nervous system, which is

most known for its role in the fight-or-flight response.

If you’re not familiar with it, of course we’ve covered it, and

you can check out that video to learn about it in-depth.

But back to the researchers -- When they were examining the sympathetic nervous system in mice,

the researchers found that it was more specialized to respond to specific stimuli than previously assumed.

The scientists followed nerves in the system from where they originated in the spinal cord

to where they connect to other structures like the blood vessels, muscles, and yes,

nipples.

They found there were 8 distinct types of neurons wired to specific areas, each expressing

different genes and responding to different stimuli.

So there is actually a type of neuron that exists just to make your nipples erect.

When these neurons are activated by the neurotransmitter norepinephrine, they cause erector muscles

to contract, tightening your areola and causing your milk duds to harden.

Titillating as this information is, it still doesn’t answer why nipples need to get hard

in the first place.

What’s the point of the point?

The most obvious reason is for breast feeding.

A baby’s suckling reflex is activated when something strokes the roof of their mouth,

so a stiff nipple will help get the little sucker to latch on for a meal.

But what about when it’s time to make a baby, or when it’s cold, or when nipples

go rogue and pitch a shirt-tent for no obvious reason?

Science is a little more perplexed about that.

It’s possible that hard nipples are supposed to serve as a signal of arousal, but it’s

a pretty terrible signal if it also shows up just because it’s cold.

That’s like having a thermometer where all the numbers are replaced with winking emojis,

it tells you nothing!

It’s possible we get nipply when it’s nippy because the muscles in our areolas and

under our hair follicles respond to the same stimuli. The scientists who discovered what

I will heretofore call the “nipple neuron” found another kind of neuron that also responds

to norepinephrine and causes your hair to stand on end.

This might be a vestigial trait from when we were more hirsute, and our hair puffed

out to trap air and keep us warmer.

It’s also frequently suggested our hair rises in stressful situations in an effort

to make us look bigger.

You can imagine how puffed out hair would be helpful when you’re being attacked by

a predator, though it’s a little harder to see how stiff nips will intimidate a bear.

Maybe it’ll think you’re aroused and be kind of weirded out.

If the only surefire reason nipples get stiff is to help with breastfeeding, then why do

men even have nipples?

It’s a classic question, and it’s one that deserves a classic episode, so I’ll

let Laci Green explain it here.

The human body is totally fascinating and awesome and if there are any weird bodily

phenomenons you’d like us to explain, tell us!

You can let us know in the comments, subscribe for more and I'll see you guys next time on DNews.