Scientific development of the instinct theory consisted mainly of drawing up lists of instincts. In 1908, William McDougall (1871-1938) postulated 18 human instincts and within 20 years, the list of instincts had grown to about 10,000.
Although instinct theory has long been abandoned, sociobiologists have adopted its evolutionary perspective considering the new wide range of human behavior, from the standpoint of natural selection, from aggression to interpersonal attraction, and the survival of humans as species.
