-_ The Pilomotor Reflex _-

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   A reflex that keeps accompanying us from the origins of our species but, do we know exactly what it is and what are its functions?

   In an introductory way, the erection of our body hair was part of our adaptation and survival in hostile environments.

   Fundamentally because of two external agents, which are mainly:

• The cold
• The predators

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The cold

   Obviously we are not talking about the cold that we can spend now and with which we can wear scarves, a hat and gloves and matter solved...

   I am referring to the sudden glaciations that have been happening for millions of years, especially in the Pleistocene, with an average duration between 50,000 and 75,000 years, and which directly involved the extinction of some species.

   And in these gelid environments is where our beloved pilomotor reflex fulfilled its mission and helped our survival:

• Before this stimulus of cold the thin muscular layer located in our dermis and connected to the hair follicle, it is responsible for raising the hair when tightening, and at the same time gather the skin that surrounds the hair, isolates the air that is trapped between the hair and the skin, what generates heat.

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   An insulation system that reminds me of wetsuits, where the film of water that comes into your suit and which you warm up immediately with your body heat, is the one that precisely serves as insulation.

   It must also be said that at that time we had much more body hair than now and that it did fulfill a true insulating function, which today could be considered lost.

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The predators

   The other function, as some species of animals continue doing today, was to increase our body volume by erecting our body hair to confuse the predator and make him think we are bigger and stronger than we really are.

   This function does not make much sense now in our species, but imagine at that time, with the great number of predators and having to face the fearsome lion of the caverns, for example; any resource was welcome...

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   A third factor that continues erecting the body hair, which I left for the end as the least important at the level of evolutionary adaptation, is by sensory excitation.

   Who has not got goose bumps watching their favorite movie, listening to a masterful piece of music or the by warm kiss on the neck from their partner?

   So you see, a curious reflection that we could almost call vestigial at this stage of evolution, but that certainly fulfilled its tasks.

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Sources:

http://www.muyinteresante.com.mx/preguntas-y-respuestas/15/02/9/explicacion-piel-gallina/

http://ve.emedemujer.com/bienestar/salud/piel-gallina-reflejo-supervivencia/

http://mitocondriacientifica.blogspot.com.es/2016/09/estructuras-vestigiales-vestigios-de.html

http://historiaybiografias.com/glaciaciones/

http://www.artehistoria.com/v2/contextos/5693.htm