Relationships are important in order to live happier lives and understanding how relationships are formed can help people form more successful relationships. Most people don’t know that the way we choose romantic partners it’s heavily to do with evolution, natural selection and adaptive characteristics rather than just what we think is personal preference.
Individuals tend to choose partners that are adaptive. Adaptive characteristics are those that lead to an increase in the chance of survival of an individual or their reproductive abilities. Natural selection favours adaptive genes because more children mean more genes in the next gene pool. Sexual selection means being attracted to the opposite sex due to adaptive characteristics which lead to more reproduction.
The problem with evolution as a reason for how we choose partners is that it is hard to falsify and difficult to test. This is because it will take millions of years to actually be able to test evolution's effects on relationship formation which makes it impractical. Furthermore, the theory about evolution being the only consideration when it comes to choosing romantic partners is ultimately reductionist because there are other biological, cultural and cognitive factors that go into deciding how we choose our partners. Another fundamental difference is that people are inherently different and therefore make different decisions based on various personal factors such as culture and individual differences such as one's upbringing.
A study was conducted by Waynforth and Dunbar (1995) where adverts were collected from a newspaper and sorted by age and keywords such as attractiveness resources etc. These adverts were called ‘Loving Heart’ adverts and were a way for individuals to describe themselves and what they are seeking and offering in a relationship as a way to find a partner. The results of this study showed that generally women offered attractiveness and men requested attractiveness in the same way that men offered resources while women requested resources. This not only tells us that women want resources and men want attractiveness in a partner, but also that women are aware that men want attractiveness and therefore offering it.
Another evolutionary reason for how we choose romantic partners are pheromones. Pheromones are chemical messengers which are released by one individual and can then be detected by another and influence behaviour. The main pathway through which pheromones are processed is the accessory pathway which starts in a specialised organ called the VNO. Most mammals communicate via pheromones as they all have functioning VNOs. However, humans don't have functioning VNOs which makes us question whether humans communicate via pheromones in the first place as they cannot even detect them. However humans have a network of neurons that is similar to the neural pathways that mammals have such as the pituitary gland and the limbic system. Since the pituitary gland can control hormones, it is possible that pheromones can control hormone levels throughout the body which means that they could influence behaviour.
Similar to evolution, this idea around pheromones is quite reductionist because it suggests that human relationship formation and attraction is only influenced by pheromones, but there are clearly other factors involved. Although pheromones may cause a change and have an effect on the endocrine system, it is unclear whether this will influence a change in behaviour. Furthermore, studies to do with pheromones are very hard to replicate as it seems that some individuals are more susceptible to pheromones than others and detect pheromones more easily. We are not very confident about pheromones influence on human behaviour but various studies have found that intense concentrations of pheromones can cause a change in testosterone levels in men.
In conclusion, humans form relationships due to a variety of factors of which the most obvious is evolution, that causes individuals to choose adaptive partners. High concentrations of pheromones may also cause attraction between individuals but our confidence in this is not very high.