Evolutionary Theory - John Bowlby
Proposes attachment is motivated by an innate instinct that has developed through evolution.
Bowlby suggests there are 4 aspects to his attachment theory, these are;
Critical period - He says that there is a period of time for developing an attachment. (0 -2 1/2 years) If a child has not developed an attachment in this period Bowlby suggests they will suffer from increased aggression and reduced intelligence. Lorenz - goslings (geese study)