Biological theories of crime are based on the belief that criminals are physiologically different from non-criminals (Bohm & Vogel, 2011). Bio criminologists assume the difference between criminals and non-criminals is the result of a complex interaction between biochemical and environmental factors. In an effort to test biological theories, researchers have to use measurement and statistical analysis to demonstrate whether or not significant structural or biochemical differences between criminals and non-criminals exists. Historically, it was believed that the cause of a crime was biological inferiority, criminals produce certain physical or genetic characteristics that distinguished them from non-criminals. However, this way of thought has lost favor among today’s bio criminologists. Several different methodologies have been employed to detect physical differences between criminals and non-criminals. These different methodologies are physiognomy, phrenology, criminal anthropology, study of body types, heredity studies, and scientific studies of brain function and structure (Bohm & Vogel, …show more content…
Between 1914 and 1930, it was believed that crime is the product primarily of people with a low level of intelligence. It began getting more attention in the mid-1970s and even more in the mid-1990s. In the early 1900s, studies were conducted on prison inmates which revealed that a high percentage of around 89% had an IQ of less than 75. The normal range for IQ today is 90 to 110. This has made many theorists believe that intelligence plays a significant role a person’s criminality. In the mid-1990s, it was believed that IQ was primarily the product of genetics, and that genetic differences in intelligence could, in large measure, explain racial differences in crime. Primarily this is stating that Blacks commit a disproportionately high percentage of violent crime is due to the genetically lower IQ levels. A person’s IQ determines their ability to control or restrain their impulses. A problem with this would be that this would mean that Blacks are less responsible for their crimes committed because their IQ related lowered impulse control (Bohm & Vogel,