Goose bumps are one of those phenomena that remind us that the separation between human beings and the rest of the animals is, deep down, a mirage, something artificial. Our organism is constantly going through hundreds of physiological processes that regulate the way we react to our environment, in theory to better adapt to its variations.

Now… in this case, why do we get goose bumps and how does this relate to our emotions? Let’s look at it.

What is goose bumps?

A summary definition of goose bumps is as follows: it is a state of the skin in which the body hair is bristly, so that as this hair is very fine and short in humans, it seems that tiny “mountains” appear on the surface of it. The hairs stand on end , but we usually pay more attention to the part of the skin that forms the base of the hair.

Skin hair straightening, known as piloerection in more formal or scientific contexts, is performed by small muscle fibres linked to the base of each hair.

Moreover, this phenomenon does not usually occur in isolation, but is related to changes in states of consciousness and, in particular, in emotional states. Thus, goose bumps have a physiological dimension and another psychological dimension related to emotions . Next we will explore in a little more detail what we know about each of these two facets of having goose bumps.

Physiological mechanisms of piloerection

It is known that the phenomenon of goosebumps, also known as horripilation, is a vestigial reflex that usually has an adaptive function in mammals in general , since this group of animals is characterized by having hair.

The mechanism by which these bumps appear on the skin over a short period of time is as follows.

1. Activation of the sympathetic nervous system

This part of the nervous system is the circuit of nerve cells that intervenes when certain environmental stimuli make us react in a state of more intense activation than normal. For example, it is the type of context in which patterns of attack or escape behaviour are usually activated .

2. Stimulation of the piloerector muscles

These tiny muscle fibres are connected to the sympathetic nervous system and act as a bridge between the latter and the hair follicle, where they are inserted. Upon receiving a signal from one of the nerves, these smooth muscle fibers contract by pulling the hair upward.

3. Changing the hair shaft

In the normal state, by default, body hair is arranged at an angle. That is, falling on one side, instead of being perpendicular to the skin. When it is tightened by the piloerector muscle, the trajectory of the hair axis is straightened, so that instead of being almost stuck to the skin, it is pointed. The tension that is generated between the skin surrounding the base of the hair on the one hand and the muscle fibres on the other makes a bulge appear in the part of the skin where each hair appears.

Why we get goose bumps: evolutionary functions

As we have seen, goose bumps are something related to vestigial reflexes that come to us through a line of ancestors who did not belong to our species and who probably had much more developed body hair than we do. Thus, the piloerection could constitute the difference between having more or less offspring, or between surviving or not surviving . Specifically, it has constituted an advantage for the following reasons

1. Helps insulate from the cold

Pilotage occurs, among other things, when the body is exposed to the cold, so that body hair becomes more fluffy and creates a wider insulating layer between the skin and the environment. In this way, body heat is better conserved .

2. It is associated with the situations of danger and reproduction

Another usefulness of goose bumps, at least in our ancestors and in the rest of the mammals characterized by having the densest and thickest body hair, is to provide the organism with a way to appear larger, which is useful in case other potentially dangerous animals that may be hesitant to attack or not are nearby .

On a social adaptation level, moreover, bristly hair is a quick way to make others aware that there is a danger nearby, as it affects the whole body and, whenever you look in that direction, it is easy to see.

On the other hand, sexual arousal is also capable of producing bristly hair, which can be associated with the need to communicate interest or to make a certain status known . The latter is something that in mammals is intimately linked to reproduction, especially in the case of males.

The case of the human being

In the case of humans, the range of sensations we can have is more varied than that of most mammals, since our mental processes are very enriched from the contextual information articulated from abstract thought.

Therefore, goose bumps can appear in many situations where a very intense emotion invades us, such as listening to music, being touched by a person, or even listening to a speech or reading a book. In this case, evolutionary usefulness loses its relevance: the hair bristle has no specific function, it simply exists as a consequence of a natural evolutionary process which has led to us (in the case of our evolutionary line).