Theories which existed before positivist theory of crime were phrenology and physiognomy theories. Johann Lavater, the physiognomist, thought that the shape of the skull and some facial features had an impact on a human behavior and actions. Later,  positivist theorist of crime Cesare Lombroso took Lavater’s ideas and began exploring other physical traits of a body. Lombroso, the criminal anthropologist, not only researched the facial features and the shape of the skull, but social conditions of individual like unemployment and medical history of illnesses. He compared a large number of criminals and non-criminals using human physical traits like: ear size, hair length and other. Goring, the main criticist of Lombroso, conducted the research on crime heredity, but didn’t find any differences in facial features or other human physical traits between prison inmates, asylum inhabitants and non-criminals. The only physical difference Goring found between an experimental and control group was the significant dissimilarity in body weight and stature. The criminals in Goring’s research tends to have the lower weight and small stature. Positivist's theorists of crime argued that human behavior is pre-disposed and fully determined by individual differences and biological traits. In short, terms, what drives people towards crime is not a matter of free-will. The positivist crime theorist and criminal anthropologist Cesare Lombroso made attempts to scientifically prove his thesis that criminal offenders were physically different from  non-offenders. Lombroso stated that atavistic features are more akin to savages and criminal offenders. This view was held by many biological positivists. Positivist theory of crime presumed that scientific study of criminal behavior should find the"causes" of such behavior. They also believed that the causes of crime are beyond the control of the individual. Explanations of positivist theory were deterministic. Lombroso was influenced by Darwinian principles of evolution and used these ideas to support a thesis on inferiority of criminals. Positivist theory of crime implemented the idea of social Darwinism that individuals or groups develop certain physical and psychological attributes, which allow them to function more efficiently in the social and natural environment. We can object to positivist theories of crime that the theories never accepted the idea about the equality of gender roles. Lombroso thought that males were more lenient to a crime, because they were more masculine that females in general. Italian historian Renzo Villa thought that Lombroso's attempt to identify signs of criminality using biological traits are an inevitable result and part of the contextual development of nineteenth-century penal science and medicine. The positivist theory of crime understanding  was limited on the external appearance or phenotype properties as the way to identify the physical characteristics, which were present in criminal approach of phrenology.