Aggression has been explained as an instinct that is directed externally toward others in a process called displacement, and it has been noted that aggressive impulses that are not channeled toward a specific person or group may be expressed indirectly through socially acceptable activities such as sports and competition is a process called catharsis. Biological, or instinctive, theories of aggression have also been put forth by ethnologists, who study the behavior of animals in their natural environments. A number of ethnologists have, based upon their observations of animals, supported the view that aggression is an innate instinct common to humans.