The problem with the nature-nurture debate is that this is an inadequate way of understanding human freedom. Like every other organism, humans are shaped by both nature and nurture. But unlike any other organism, we are also defined by our ability to transcend both, by our capacity to overcome the constraints imposed both by our genetic and our cultural heritage. It is not that human beings have floated free of the laws of causation. It is rather that humans are not simply the passive end result of a chain of causes, whether natural or environmental. We have developed the capacity to intervene actively in both nature and culture, to shape both to our will. To put this another way, humans, uniquely, are subjects as well as objects. We are biological beings, and under the purview of biological and physical laws. But we are also conscious beings with purpose and agency, traits the possession of which allow us to design ways of breaking the constraints of biological and physical laws. All non-human animals are constrained by the tools that nature has bequeathed them through natural selection, and by the environmental conditions in which they find themselves. No animal is capable of asking questions or generating problems that are irrelevant to its immediate circumstances or its evolutionarily designed needs. When a beaver builds a dam, it doesn't ask itself why it does so, or whether there is a better way of doing it. When a swallow flies south, it doesn't wonder why it is hotter in Africa or what would happen if it flew still further south. Humans do ask themselves these and many other kinds of questions questions that have no relevance, indeed make little sense, in the context of evolved needs and goals. What marks out humans is our capacity to go beyond our naturally defined goals such as the need to find food, shelter or a mate and to establish human-created goals. Our evolutionary heritage certainly shapes the way that humans approach the world. But it does not limit it. Similarly, our cultural heritage influences the ways in which we think about the world and the kinds of questions we ask of it, but it does not imprison them. If membership of a particular culture absolutely shaped our worldview, then historical change would never be possible: If the people of medieval Europe had been totally determined by the worldview sustained by medieval European culture, it would not have been possible for that society to have become anything different. It would not have been possible, for instance, to have developed new ideas about individualism and materialism, or to have created new totals of technology and new political institutions. Human beings are not automata who simply respond blindly to whatever culture in which they find themselves, any more than they are automata that blindly respond to their evolutionary heritage. There is a tension between the way a culture shapes individuals within its purview and the way that those individuals respond to that culture, just as there is a tension between the way natural selection shapes the way that humans think about the world and the way that humans respond to our natural heritage. This tension allows people to think critically and imaginatively, and to look beyond a particular culture's horizons. In the six million years since the human and chimpanzee lines first diverged on either side of Africa's Great Rift Valley, the behaviour and lifestyles of chimpanzees have barely changed. Human behaviour and lifestyles clearly have. Humans have learned to learn from previous generations, to improve upon their work, and to establish a momentum to human life and culture that has taken us from cave art to quantum physics and to the unraveling of the genome. It is this capacity for constant innovation that distinguishes humans from all other animals. &nb