Outline and evaluate evolutionary explanations of two types of mental disorders: One type of mental disorder that has been explained in terms of evolution is depression. There are two types of depression, unipolar depression that is ‘normal’ depression and bipolar depression, which is also referred to as manic depression. Bipolar depression consists of extreme highs and lows, this sort of depression has been highly linked with creativity, and many people such as Winston Churchill, Van Gogh and Virginia Woolf were thought to have bipolar depression.
It is thought that bipolar depression may have been naturally selected in evolution because the creativity and intelligence, which accompany the disorder, were very highly valued characteristics and meant that people with bipolar depression were more likely to attract a potential mate. Bowlby suggested that depression has been past through evolution because it enables people to over come detachment. Bowlby believes that everyone needs to form a bond to an attachment figure and that if that bond is broken you go through three stages, protest despair and detachment.
Depression comes with the despair and people must go through that step before moving on to detachment. This theory is called deprivation depression. Another theory that suggests that depression can be explained evolutionarily is defeat depression. Stevens and Price proposed defeat depression or the rank theory, they suggested that because humans live in groups there must be a hierarchy and for it to work there needs to be people who dominate.
The theory suggest that depression has been past on because people who accept loss in competition are less likely to get injured and therefore survive to reproduce, if the person becomes depressed after loss they will not again and therefore survive longer, this is know as yielding behaviour. Studies by Belsher and Costello 1988 support this theory, they found that 50% of people that suffer from bipolar depression would relapse within the first two years of recovery, a common factor in these cases is repeated criticism. The theory would suggest that continually being criticised would bring on a relapse.
Another suggestion is that depressing exists today because of ‘genome lag’ Nesse and Williams 1995 suggested that depression is increasing because of living in highly competitive urban societies. They suggest that this is a consequence of media image of ideal life styles and material possessions, which leaves people feeling dissatisfied. Another mental disorder, which has been attempted to be explained though evolution is anxiety. Anxiety such as phobias can sometimes be a good response to have to dangers, and would therefore help to keep you safe.
For example being scared of heights may stop you walking dangerously close to the edge of a cliff. Being scared of spiders may stop u being bittern by a poisonous one and dieing. Although some people believe that phobias are not inherited but learnt through classical conditioning. Seligman 1971 explained this in terms of ‘biological preparedness’ he suggested that we are pre-programmed to develop fears after experiencing dangerous situations, for example a study showed that 38% of people that survive road accidents develop fears related to driving. Another form of anxiety disorders is obsessive-compulsive disorders.
These are disorders that involve obsessive thoughts and compulsive actions. For example checking behaviour like making sure doors are locked over and over again. This can be explained in evolution because if our ancestors kept checking there possessions or food stores then they were less likely to be stolen and therefore they were more likely to survive. These genes may have been past on and what we see today as an obsessive compulsive disorder may just be an exaggerated form of behaviour that was once a survival technique and valuable enough to be passed on.