In criminology, environmentalism is the assumption that variations in criminal behaviour result only from variations in environmental factors, especially social environmental factors. The biosocial perspective is quite different. It assumes that biological and environmental factors interact to affect criminal behaviour. Social environmental explanations have dominated the field of criminology for at least the past century. Supporters of this perspective argue that because criminal is an ever-changing legal designation, it makes no sense to believe that crimes are the result of biology. Biosocial theorists concede that criminality is a legal concept, but argue that at the core of the concept are acts that are recognised as unacceptable in all societies. The theme of this book is Biology matters when trying to understand criminal behaviour. This is not to exclude social factors but to maintain that social and biological factors interact to affect our varying tendencies to violate criminal statutes. Despite the conceptual simplicity of the biosocial perspective, the evidence that supports it is often complex and rests upon a number of biological principles that many criminolog