In this dissertation I will consider the extent to which our ethical actions are determined by evolution, as well as the consequences of a view that holds that ethical behaviour arose from evolutionary processes. I will further investigate whether evolution can supply a complete account of ethics in the physical world, without sacrificing human freedom and rationality. To do this, I will start by considering the possible negative consequences of applying evolution to human behaviour, in the forms of Social Darwinism and eugenics. I will argue that while these systems of thought are ethically and scientifically unsound, there is strong evidence for the evolutionary origins of ethics, where ethics can be seen as an adaptation that offers a benefit to the individual exhibiting this behaviour. This view is supported by sociobiology, studies in primate behaviour and neuroscience. The implications of ethics as an evolutionary adaptation will be compared to Kantian morality, which is premised on freedom and autonomy, which I will argue are inconsistent with some scientific explanations. While an evolutionary account of ethics can lead to a deterministic view of our behaviour, new developments in neuroscience claim that freedom is an evolutionary adaptation. This naturally developed freedom, combined with self-consciousness, can supply us with an evolutionary account of ethics that does not need augmentation from transcendental principles.