Rank theory is an
evolutionary theory of depression, developed by
Anthony Stevens and John Price, and proposes that
depression promotes the
survival of
genes.
Depression is an
adaptive response to losing status (rank) and losing confidence in the ability to regain it. The adaptive function of the depression is to change behaviour to promote survival for someone who has been defeated. According to rank theory, depression was naturally selected to allow us to accept a subordinate role. The function of this depressive adaptation is to prevent the loser from suffering further defeat in a
conflict.
In the face of defeat, a behavioural process swings into action which causes the individual to cease competing and reduce their ambitions. This process is involuntary and results in the loss of energy,
depressed mood, sleep disturbance, poor appetite, and loss of confidence, which are typical characteristics of depression. The outward symptoms of depression (facial expressions, constant crying, etc.) signal to others that the loser is not fit to compete, and they also discourage others from attempting to restore the loser's rank.
This acceptance of a lower rank would serve to stabilise an ancestral human community, promoting the survival of any individual (or individual's genes) in the community through affording protection from other human groups, retaining access to resources, and to mates. The adaptive function of accepting a lower rank is twofold: first, it ensures that the loser truly yields and does not attempt to make a comeback, and second, the loser reassures the winner that yielding has truly taken place, so that the conflict ends, with no further damage to the loser. Social harmony is then restored.
Development
Rank theory of
depression, initially known as the 'social competition hypothesis
', is based on
ethological theories of
signalling: in order to avoid injury, animals will perform 'appeasement displays' to demonstrate their subordination and lack of desire to engage in further competition.
Additionally, rank theory attempts to explain the link between low
socioeconomic status and depression through a
psychosocial lens.
John Price formulated rank theory after noticing that monkeys