Offenders were a biologically distinct group of people exhibiting primitive characteristics - a separate species with a primitive genetic form (atavistic) whose features enabled them to survive in the wild but made them unsuited to existence in civilised society
Offenders were seen as lacking evolutionary development, their savage and untamed nature meant that they would find it impossible to adjust to the demands of civilised society and inevitably turn to crime
Lombroso argued that criminals were born, not made (supports the nature argument) and that you could determine the type of criminal by the shape of the head and facial features
Lombroso based his theory on survey data of criminal heads and bodies. He sampled the proportions of 383 skulls of dead criminals and the heads of 3,839 living ones
Lombroso didn't suggest that all criminal acts were perpetrated by people with atavistic constitutions, but concluded that approximately 40% could be accounted for in this way
Father of Criminology, shifted emphasis in crime research away from criminals being judged as 'wicked' and 'weak-minded' towards a more scientific realm, paved the way for future scientific theories
Much more likely to get the death penalty in the USA than those who were less stereotypically black looking even if they had committed very similar offences
Even if there are criminals who have some of the atavistic elements in their facial appearance that Lombroso suggested, this does not mean this is the cause of their offending
Lombroso believed that women have low intelligence and were naturally jealous, but maternal instincts can neutralise these negative traits; women who become criminals had masculine characteristics which were fine in a man but create a monster in a woman; he claimed that women had not evolved as much as men