Instincts are best understood as hard-wired biological predispositions that are not learned, but are present at birth. Developmentally, some instincts are immediately present, some disappear and some are latent until several years go by.
Modern technology and a settled social environment has made the use of instincts in humans less prominent when compared to animals in the wild. The most accepted inborn instincts within humans are: the instinct to survive, the instinct to reproduce, the maternal instinct, and the fight or flight response.
Human instinct can be difficult to categorize when compared with habits. Take for example how eating has become a habitual activity, with or without hunger, humans can eat or choose not to eat (anorexics and fasting), thus placing the common animal instinct to feed as questionable within humans. Even the instinct to survive is not fully accessible to all humans. Without care and guidance the human child cannot survive, babies often place dangerous objects and substances in their mouths which could kill them, some teenagers enjoy dangerous drug use and some adults drive at dangerously high speeds; thus constantly risking survival and lessening its esteem as an inborn instinct. Research has shown that the maternal instinct can be observed by an increase in hormones in the woman when she first comes into contact with her child. These hormones trigger protective feelings for the child. However, not all women have a maternal instinct as some women go through post partum depression.
The most consistent instinct is the social instinct. It especially exists in children who instinctively need to be cared for, without social interaction a child can die, become depressed and not develop well. Adults continue to establish the social instinct through social systems such as governments, clubs and families.