According to Freud, nothing is more important than the choice for a reproductive mate. He views sex in terms of libido, which can be expressed with sexual behaviour. On the other hand, Bandura would argue that sexual arousal leading to an orgasm is a positive reinforcement that will lead to the couple repeating this act more often. The evolutionary biology to understand social behaviour in animals is called socio-biology. The socio-biologist will study human sexual behaviour by examining patterns in other species. From the evolution perspective the most important function of sex is producing healthy offspring. This happens through sexual selection, in which animals that are best at adapting to their environment will survive. Humans choose their mates based on physical attractiveness, which according to the socio-biologist is a way of evaluating one’s health and vigor. This could indicate a better offspring. However, if people only chose mates based on maximum reproductive success, attractiveness should be a more important indicator of mate selection in unhealthy countries.There are several hindrances that can occur with reproduction, two of them are infant vulnerability and maternal death. The first is reduced when the mother is providing care continuously, including breastfeeding. Also, a pair-bond between mother and father and attachment between the child and its parents limit infant vulnerability. Parental investment...