What sort of person should you be to increase your chances of survival? Are conscientious people better at looking after their health? Do neurotic people increase chances of survival if their tendency to feel anxious drives them to a state of constant vigilance? Are introverts more risk-averted and therefore likelier to live longer lives?
It is well known within the field of psychology that roughly 50% of variation in personality traits amongst different people are due to genetic factors. If personality is partially due to genetic factors then evolution, which impacts gene selection, has influenced who we are. What’s more, evolution is a stunning example of how game theory can be applied.
Evolution via natural selection suggests that those with the genes more helpful for survival live to pass on those genes, a process commonly referred to as ‘survival of the fittest’ – although technically speaking, it is the survival of the fittest genes, and not exactly survival of the fittest organism. When we say that evolution can have an impact on personality, what we really mean is that evolution operates on genes, genes then code for brain structures, brain structures then affect how we process information, and this in conjunction with our social context can impact on our personality.
If 50% of personality variation is due to genetic factors then it suggests that there are personality traits which have implications for survival and fitness. In psychology, the five major umbrella traits that have been identified are openness, conscientiousness, extraversion, agreeableness and neuroticism. A gene cannot be held accounable for the presence of a certain trait i.e. there is no gene for neurotism for example, but someone who has a gene that leaves them more prone to feeling anxious may score higher on a neuroticism scale.
So if evolution operates on genes which indirectly influences levels of a certain personality trait, how are these genes, and by extension, traits, selected for?
One way is through antagonistic pleiotropy. This basically means that all traits have ‘fitness trade-offs’ – for example the benefits of being very agreeable is that you have harmonious relationships and are unlikely to provoke hosility (which may have implications for survival), but the costs are that you are vulnerable to exploitation due to your unselfish nature. Therefore an optimal level of agreeableness would be some way between the two extremes; don’t be a pushover, but don’t be completely disagreeable either. This means that traits can be ‘selected’ according to a fitness-maximising balance.
Another way is through frequency dependent selection. Succinctly put, if all your neighbours are pursuing one strategy, it may pay to pursue another. A good illustration is the Hawk-Dove game. Basically, hawks and doves compete for food resources; while hawks compete aggressively, doves back down as soon as their opponent initiates any aggressive behaviour. Two doves will share, while two hawks will fight. Where a hawk encounters a dove, the dove will always give way. The payoff matrix is therefore:
Although hawks often win, doves are never injured. In a population of many hawks, it pays to be a dove – while food is scarce, at least you aren’t being attacked. When doves are prominent, life as a hawk wouldn’t be bad – you can easily wrestle off food from doves. Therefore the best strategy to pursue is not static and depends on the frequency of the strategies adopted by your feathered-friends.
We can conclude that these theories provide a superficial case for the importance of moderation in personality characteristics (not being too much or too little of one thing), and the strategic adoption of indie personality traits (going against the mainstream). However, what really makes a person successful is too complex to address here, but some insight into how personality traits are selected to optimise fitness may be an acceptable starting point, if not just something elightening to read. What’s more, it illustrates the many applications of game theory, and the cross-disciplinary relevance of economics.