Theory is an explanation that has not yet been proved. The theory of heredity has been traced back as far as the Old Testament. However, the first systematic efforts to identify biological causes of crime can be traced back to Franz Joseph Gall (1758-1828) who presented Phrenology as a causation of criminal behavior. Phrenology is a study based on the outmoded idea that a persons mental faculties are indicated by the shape of his or her skull. In all theories of crime, the question of what factors are responsible for people who seem to be criminals from an early age has intimidated great thinkers for thousands of years. Physiognomists believed that a person's character can be ascertained from external appearance. Phrenologists taught that a the brain consists of many different faculties each governing an aspect of human behavior and thus contributed greatly to the early 19th Century beliefs of criminality being a mental illness. Degeneration theory was brought about by the Phrenologists view that people can induce criminal activity by over eating, drinking and sex. Cesare Lombroso put forth yet another theory of crime: criminal anthropology. Criminal anthropologists taught that some criminals are unchangeable and doomed to lives of crime. Degeneration theorists and criminal anthropologists converged to convince the general public and policymakers of the need for eugenic policies to prevent the socially undesirable people from reproducing, which became the Feeblemindedness Theory. Scientists for centuries have proposed a wide range of biological explanations of crime, some incorporating premise from the past, others striking out in new routes.
Cesare Lombroso (1835-1909) often known as the "Father of Criminology", was an Italian physician who replaced the notion that "human action expresses personal choice and is not determined solely by physical or divine forces with the notion that all events, including human choices and decisions, have sufficient causes.