Why We Can goose bumps? The following reason

Some of the specific conditions experienced as fear or cold can cause the body's reaction to shiver. Why did this phenomenon happen?
Chill is a physiological phenomenon that is inherited by our ancestors since time immemorial and experienced by all mammals.
When people feel goose bumps, not just the hair on the skin that stands but is also accompanied by the emergence of the mounds where the hair grows. The emergence of the pile due to the contraction of small muscles.
As quoted from Scientificamerican, chills occur because a person's subconscious release of stress hormones called adrenaline. Adrenaline produced by humans through two small glands above the kidneys not only causes muscle contraction, but also affects many other body reactions.
In addition chill can also arise as a result of a small erector muscle contraction that is in the skin. When these stimuli produce neural changes, it happens so that muscle contraction in the hair above the skin becomes established.
Body chills may occur temporarily and disappears after a while. And everyone is not able to prevent the body's skin crawl, as well as with their faces flushed and sweaty bodies.
There are several conditions that can cause body hair on the skin stand, namely:
Cold stimuli Based on an article written by Eric Sonstroem from Indiana University in the website 'A Moment of Science', chill is a primitive reaction arising from the limbic system of the brain. When there is cold air stimulation, the hair on the tip of his skin would stand to help warm the body.
Emotional reactions Some emotional reactions can cause the body to shudder, such as fear, watching movies, seeing a work of art or listen to a music concert. Emotions that arise may cause piloerection of the hair root becomes varied and complex. But until now not known why anyone would shudder to a particular stimulus, while others do not.
Fight or flight Creeps into the mechanism of the response of 'fight or light'. When the man felt alert to the presence of a hazard, it will be out adrenaline and blood is pumped into the muscles to be increased so that the body becomes goosebumps.