16/09/2014 09:47 BST | Updated 15/11/2014 05:59 GMT

How Evolution Explains Attraction

The way relationships form between people has always fascinated me - How does science explain attraction?

Through my study of Psychology I came to understand this a little better and found it fascinating trying to explain what the science in attraction was from the evolutionary perspective.

Within psychology sexual selection theory is used to explain attraction - but what is this? Well you've heard of Darwins theory of evolution right? well unfortunately when he came up with this theory there was one big problem with it.

To give you a quick brief: Darwin's theory of evolution proposes that through a process of natural selection; the animals who are the "fittest" survive. Fitness relates to an animal's ability to adapt to their environment either physically or through their behaviour. So what would happen over time is that animals who were born with traits that suited their environment had a greater chance to reproduce and thus pass on those successful traits to their next generation.

But this theory had a problem as Darwin noticed many animals had features and traits that actually appeared to hinder their ability to survive within their environment. For example take the peacock and its huge tail. Why would an animal have such a huge tail when it simply added weight and made evasion from predators more difficult? Surely natural selection would filter such a trait out? It should really but not unless there was something else that was fighting against natural selection.

This is where he created Sexual Selection Theory; the idea that some features in people evolve simply because the opposite sex finds them attractive - but why? Why are some features more sought after than another? These features evolve because they show the opposite sex that even if they have traits that hinder them, they can survive which ultimately proves their strong genes. A man named Zahavi explained this better but more on his theory in a moment.

Take men and women for example; Men find youth and beauty far more important in their female partner while women tend to place an emphasis on the ability to provide and care for them (resources). Physical traits and appearance are important to women but what we've found is they tend to place a much less emphasis than men.

Evolutionists propose this would have developed because they are more concerned with investment into relationships and what a man brings to the table overall. Women produce a very limited supply of eggs which gives them only a small window to become pregnant (approx 300 within suitable ages) and this means they need to be much pickier with their men. Whoever they decide to be with there is always the risk of abandonment which poses a big problem for women as they are the only ones that can be sure of paternity and must then raise a child only they can be certain is theirs. Men cannot be sure of paternity hence sexual selection actually promotes them to be more promiscuous to maximise their chances of passing on their genes . Therefore men and women are actually fighting between opposite pressures from evolution with men in theory designed to be more promiscuous to maximise the chances of reproduction while women are fighting to keep hold of a man so he can invest in them and their child.

Therefore for men to choose their partner; attraction needs to be based on "signals" that tell a man the woman is fertile and its for this reason women place a greater emphasis on appearance, makeup, nails, hair, lipstick, get the idea. It's also why youth is more important to men as this is a key sign of fertility for them.

For women however they need a man thats able to provide, care, be emotionally supportive for them and their child and support them all while ensuring they don't abandon them. Security and stability is therefore more important to women overall from an evolutionary perspective.

From a physical perspective signals for attraction in men are the broad shoulders, square jawline and signs of physical strength. This tells a woman any children will be healthy and strong as innately they are looking for features that could be passed on to children. Such features can only be produced in a man with high testosterone which is actually bad for the immune system however this brings me back to Zahavi's theory; if a man is able to display such traits and still be seen as physically strong he must have good genes right? Just like the peacocks tail. Therefore this becomes innately attractive for women.

Unfortunately as with most evolutionary theories for behaviour it becomes difficult to prove this either way. Intelligence is seen as attractive for some but then evolutionists argue this is because its a key quality needed for survival. You see thats the problem with evolutionary approaches to behaviour- You can never prove or disprove them for certain. In fact although science may be able to explain attraction using evolution; theories for the formation of relationships suggest something else goes on instead which is more psychological.