These tendencies seem to be hard-wired and seem to have a developmental purpose.
Infants commonly show a fearful response to loud noise or the sudden loss of physical support.
Reluctance to be separated from one's caregiver is a normal, healthy response in young children and indicated the development of healthy attachment. When a child starts to walk on its own, fear of strange animals is an adaptive response. Performance anxiety can appear in late childhood and social phobia in adolescence. Some degree of separation anxiety is a sign that the preschooler has developed healthy attachments to loved ones. In many cases, it stops within 3-4 minutes after the parent leaves.