Human behaviour was understood - or more correctly, misunderstood - during the nineteenth century as an expression of biological instincts. Along with other patterns of human behaviour, criminality was explained on biological grounds.
Lombroso: early research
In 1876, Caesare Lombroso (1835-1909), an Italian physician who worked in prisons, developed a biological theory of criminality. Lombroso described criminals as having distinctive physical characteristics - low foreheads, prominent jaws and cheekbones, protruding ears, hairiness, and unusually long arms - that resemble human beings’ apelike ancestors. In other words, he viewed criminals as evolutionary throwbacks to lower forms of life.
Because of their biologically based inadequacy, Lombroso reasoned, such individuals would think and act in a primitive manner likely to run afoul of society's laws. Although toward the end of his career Lombroso acknowledged that social factors play a part in criminality, his early claim that some people are literally born criminals was widely influential in an era in which biological explanations of human behaviour were popular.
Lombroso’s findings were based on seriously flawed research methods. He failed to see that the physical characteristics he found in prison and linked to criminality also existed in the population as a whole. Early in the twentieth century, the British psychiatrist Charles Buck-man Goring (1870-1919), who also worked in prisons, published the results of a comparison of thousands of convicts and noncriminals. There was a great deal of physical variation within both groups, but Goring’s research showed there were no significant physical differences between the criminal and noncriminal categories of the kind suggested by Lombroso.