Although from an evolutionary perspective women are usually the choosy sex, if a human male has the desire to reproduce he may seek certain qualities in a potential mate who could be the mother of his offspring. Humans have the ability to rely on biological signals of reproductive success and non-biological signals, such as the female's willingness to marry. Unlike many animals, humans are not able to consciously display physical changes to their body when they are ready to mate, so they have to rely on other forms of communication before engaging in a consensual relationship.