The scientific exposition in this column will give you goose bumps!

I recently had a case of cutis anserina. It wasn’t pathogenic or particularly virulent. There is a difference between the two, you know. I don’t mean there’s a difference between cutis and anserina. I mean there’s a difference between pathogenicity and virulence. Pathogenicity is when something like broccoli has the ability to make you sick. Virulence is a word used to describe a higher degree of sickness, such as in broccoli for breakfast!

Actually cutis anserina is considered a normal condition, at least in geese, and refers to the tiny raised bumps we get in our skin when we’re cold or frightened. These bumps are called “goose bumps” because goose feathers grow from follicles in the skin similar to our hair follicles. When the goose is plucked of its feathers, little bumps in the skin are left behind that resemble the similar condition in humans.

I don’t think most people pluck their own geese anymore. As a matter of fact, I don’t think most people pluck anything: turkeys, chickens or canaries. (Actually, I think the latter just die in coal mines without ever worrying about being plucked.) Anyway, if one has never plucked anything (except maybe a guitar string), one has truly missed out on a unique experience.

I don’t know why geese were chosen for the name of this phenomenon. Many bird skins do the same thing when plucked of feathers. They could have been called “pheasant bumps.”

Even more interesting, many other languages use the same terminology. Germans use gänsehaut. Italians use pelle d’oca. Other languages substitute different birds like chicken or duck for goose.

We often get goose bumps from going out in the cold. See, your hair follicles seldom grow straight out of the skin. They grow at an angle. Potentially, each follicle has a tiny muscle attached to it and collectively they are called arrectores pilorum. When we get cold, these muscles contract and cause the hair to point straight up. This distorts the follicle and causes the little bumps to occur. The hair, being flexible, bends over, trapping air under the hair.

Combined with the heat of the contracting muscle, this reaction acts as insulation and helps the body retain heat. It works great if you are covered with hair as many animals like lions, tigers and bears are. For most humans, it is not terribly effective, although I have observed some who could probably survive an arctic night this way.

I got my cutis anserina from listening to music. I know that sounds weird. However, the arrectores pilorum are controlled by the sympathetic nervous system, a system over which we have little conscious control. This system often mitigates responses to stressful and emotional situations by releasing numerous hormones related to fight or flight. One of the general responses is called piloerection, the contraction of the arrectores pilorum.

Many animals respond to stress by contracting the erector muscles. The porcupine is an example. In that case it is a very real defense mechanism. (In humans this is simply called a prickly personality.)

Other animals, like dogs, may erect the pilli and thereby appear larger than they actually are. This can threaten other challengers.

In my case, it just makes me look like a plucked goose.

Oddly, goose bumps can also be a sign of pleasure. The pleasure experience is driven by the neurotransmitter dopamine. Dopamine causes changes in heart rate, temperature and breathing patterns.

It also changes the skin’s electrical conductance. Muscles in the skin are thus affected, and the erector pilli contract causing goose bumps and chills (shivering of the arrectores pilorum).

So music can apparently induce emotional responses involving dopamine, which changes electrical conductance of the skin, which causes the arrectores pilorum to contract, which gives me cutis anserina.

Sure beats broccoli for breakfast.

Gary McCallister, .(JavaScript must be enabled to view this email address), is a professor of biology at Colorado Mesa University.

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