Darwin’s evolutionary theory challenged the religious beliefs (that there is a fixed separation between humans and animals) by arguing that Homosapiens and other species of ape descended from the same ape-like ancestors. This idea contradicted the creationist beliefs so much that it is still challenged in the USA and Europe today. Twentieth century science of genetics explained the mechanisms of inheritance and the way species evolve. A person’s genes do not specify or determine their behaviour.
Due to technological advances in scientific methods, the evolutionary development of Homosapiens has been recorded in much detail and has been applied to the question of human nature. Humans and closely related primates have certain similarities such as their use of tools. The larger brain size of humans compared to primates has been used to explain the language capacity of humans, however, brain evolution appears to apply more to the development on human sociality.
Although natural science has recorded the development of the capacities of humans over evolutionary time, social science has focused more on the expression of human capacities through social relations and culture in their accounts of human nature. Social and psychological observation methods give information about people in everyday social context. Archaeological burial sites suggest, that unlike animals death was treated symbolically in all human cultures. The creation and the use of symbols is seen as a defining feature of human nature. Self-consciousness (a person’s awareness of himself or herself as if from the perspective of another person) is another feature of human nature. It is understood as a capacity that develops in relationships, both in their real and imaginary aspects, as a result of the capacity to symbolize. Unlike other animals, humans are aware of their existence in time and are aware of their past and their future. Combined with the human capacity for imagining what is outside of their experience and this means that humans can be creative in their making and changing of things. In other words they can be agents. This too is a distinctive feature of human nature. (satra)
Sex is commonly seen as a natural action, as it is necessary for human reproduction and because it is experienced as driven or instinctual. Most sexual practices do not lead to reproduction and so, the idea that sex is natural because it leads to reproduction, is inadequate. For the same reason, heterosexuality and homosexuality should not logically be thought of as respectively ‘natural’ and ‘unnatural’. Homosexuality is of quite recent historical origin and this has influenced how people experience and put in to practice same-sex desires. For example, the oral period of a baby’s early. Sexual experience and its psychological significance in the baby's later life (a baby breast feeding, the sound of mothers heartbeat, the feel of skin and the smell of mother etc). This showed how sex can be understood as both natural and social at the same time, once psychological experience is also included. Experience throughout life, relies on a lifetime of meanings that are drawn from culture and social relations. This then transformed through imagination, needing and symbolization to make them creative and not determined by social structures.
Humans symbolize; they have symbolic capacity, communicate with each other through symbols and use symbols to create and understand culture. Humans have self-consciousness, developed and enacted through interpersonal and social relations. Humans are aware of being in time. This both enables symbolization and is enabled by it. Humans have imaginative capacity that enables creativity in making things, making culture and relating to people. It explains why people are agents in their lives, more than the sum of external (social and physical) and internal (biological) structures that impinge upon them. The capacities for these human characteristics must derive from nature (more specifically, genes, hormones, bodily structures and the like), but it is in the social environment, mediated by human psychology, that human nature is expressed.
