The verb shiver, of onomatopoeic origin according to Royal Spanish Academy (RAE), Alludes to to flinch or tremble. The terror, the fever and the cold are some reasons that can make a person shiver.
It should be noted that shivering is synonymous with flicker. The RAE recognizes both terms, although it circumscribes shivering to the tremor caused by the afraid or because of the cold.
For instance: “As soon as he got into the water, the girl began to shiver”, “The screams that came from outside the house made the boy shiver, who decided to hide under the bed”, “Since I contracted the disease, I can not stop shivering, I really feel very bad”.
Shivering when in contact with cold water is normal and unavoidable, although not all human beings have the same degree of tolerance for low temperatures temperatures. This means that in some this reaction is triggered when the cold is extreme, and vice versa.
The second example refers to the involuntary response to fear, which can be equivalent to that of cold, although it can also be accompanied by sweating, paleness and lightheadedness, among other symptoms. Finally, there is talk of a disease that produces fever and, therefore, a feeling of cold that causes us to shiver.
The hypothalamus and cold
It is normal for an individual to start shivering when being exposed to low temperatures. The biological root of this organic response is found in the hypothalamus, an area of the brain that functions as if it were a thermostat.
The hypothalamus is responsible for regulating body temperature: if the cold outside threatens the balance, the hypothalamus orders the muscles to move with repetitive contractions to produce energy in the form of hot. This means, therefore, that when we shiver we generate heat.
It is important to note that the muscle contractions that develop when shivering are involuntary. They cannot be avoided or controlled, since in these cases the organism considers that there is a need to raise body temperature.
Shiver in fear
“Stories to shiver with fear”, on the other hand, is the title of a book written by the Chilean author Saul Schkolnik. The work, published in 2003, presents nine horror stories aimed at children.
Just as the cold leads the body to shiver as part of a series of mechanisms that seek nothing more than to raise the temperature of the body, fear is related to a series of issues that we inherit from our most remote ancestors. For example, the brain can relate this feeling of discomfort to the presence of an insect dangerous on our body, and for this reason it leads us to shake ourselves to make it fall.
Something similar occurs with attacks of hiccups, which are characterized by a series of contractions of the diaphragm that also occur involuntarily and culminating in the closure of the vocal cords, which is why if we try to speak we emit a sound similar to «hip». One of the most common explanations for this phenomenon is that the body believes it is being poisoned and that is why it seeks to expel the toxic substance from the digestive tract with these sudden movements.
Returning to the action of shivering in response to a terrifying situation, it can also be interpreted as a primitive attempt to drive away the subject that causes it. We must understand this from a broad and relatively abstract point of view: we know that if someone attacks us on the street it will be useless for us to tremble, but it is likely that these mechanisms have arisen in our brain thousands of years ago, in the face of another kind of threats, and that in such remote cases they were useful.