Evolutionary explanations

• Natural selection is the idea that human behaviour is driven by the need to survive and reproduce.
• The Evolutionary approaches state that animals are motivated to select a 'mate' with the best possible genes who will best ensure the offspring's future health and survival.
• Anisogamy refers to two sex cells (or gametes) that are different coming together to reproduce.
• Men have sperm cells, which are able to reproduce quickly with little energy expenditure and once they start being produced they do not usually stop until the man dies.
• Female gametes (eggs or ova) are much less plentiful; they are released in a limited time frame (between puberty and menopause) and require much more energy to produce.
• The difference in the number of sex cells (or gametes) between males and females (anisogamy) means that men and women use different strategies when choosing their partners.
• Intersexual selection is when one gender makes mate choices based on a specific characteristic in the other gender, meaning that those with the trait are more likely to breed and pass the trait and so the number of individuals with this trait in the population will increase over time.
• This strategy is typically the strategy of females due to high investment cost and parental certainty of children to pick the highest quality mate from a wide selection of available mates according to attractive features that indicate good genes.
• If females have made a good choice, then their offspring will inherit the positive features of their father and are therefore also more likely to be chosen by women or men in the next generation.
• Intrasexual selection is the strategy of males due to low investment costs and lack of parental certainty to compete between themselves for access to a large quantity of members of the opposite sex.
• This competition was initially very physical, favouring large, dominant males who would father most of the offspring and so increase the frequency of their genes in the gene pool.
• This leads to Male-Female dimorphism, where enhanced secondary characteristics are selected on each gender by the opposite gender, leading to these becoming more common in the population.
• Evolutionary psychology suggests that females look for qualities in men that will help raise a child to adulthood such as resources/money, and physical characteristics linked to dominance (tall/healthy).
• Evolutionary psychology suggests that males look for signs of fertility that indicate the production of healthy offspring such as large breasts, youthful facial features such as big eyes, small nose, small chin (as younger women more fertile), and the hourglass body shape of a 0.7 waist to hip ratio as this indicates that a female is sexually mature but not pregnant.