Biological theories of crime causation tried to find casualties who affect human behavior and actions. Many scientific disciplines such as psychology, political sciences, criminal law, sociology and biology contribute to criminology. Criminology is the integration of these knowledge's that every science has about deviant, forbidden, unmoral and abnormal acts. Like many other social sciences, criminology deals with a probability and probability is tested trough statistical analysis and other methods. Criminology studies crimes, criminals, forms of criminal behavior, the possible causes of crime, social environment, victims and the social reaction on criminal acts. Areas of criminological studies can be: juvenile delinquency, penology, victimology, etiology, phenomenology, criminal prophylaxis, criminal prognosis, clinical studies, anti-delinquent policy and other. Criminal justice and theoretical criminology share many research interests and have well developed relations as scientific disciplines.

 Classification of theoretical criminology

Theories are the product of certain historical or cultural context. Valid elements of theory are contextualized again in a new theory. Theories are distant from practice, because the relations between practice and theory is often disregarded. Therefore, theory sometimes becomes a set of raw facts without any applicability.
Classification of applied criminology

Interests to research crime existed throughout history. Throughout history, crime was researched as a dynamic social phenomenon. In short, terms, crime was a relative term, because the views on crime have changed, and what was considered as a crime in the past, today perhaps is not a crime. For an example, homosexuality was a crime in not so far history.

Early biological theories of crime tried to establish a connection between physical deformity, disability and ugliness with crime, while borderline scientific disciplines such as physiognomy attempted to establish a link between facial features, personality and crime. Explanation of biological theories of crime favors biological traits as a dominant factor that will affect  human behavior and actions.

"Mens sana in corpore sano."

Throughout medieval times, physical deformities such as moles, warts and third nipples were proof of demonic possession. It was quite easy and suitable to condemn ugly persons to death.

To be ugly has fallen out of favor in medieval times.

Biosocial theories of crime causation stress out importance of biochemical conditions, genetic code, neurological conditions and influences of social environment on the behavior. Combined effect of personal biological traits and social environment will result in conformity with social norms or with crime. Other biosocial theorists point out the influence of low levels of chemical nutrients and minerals on criminal behavior. Lack of nutrients and minerals has an impact on physical growth, cognitive and intellectual development. Researches conducted by biosocial theorist show that excessively high or low levels of some chemicals and minerals such as sodium, calcium, amino-acids and others could lead to cognitive dysfunctionality, loss of memory, depression or manic behavior. Other researches find out that excessive intake of metals like iron and manganese can lead to attention deficit hyperactivity disorder (ADHD) and neurological dysfunctions. It is believed that those neurological conditions are linked with criminal behavior.

Evolutionary theories of crime

Modern evolutionary criminologists base their arguments on the work of Charles Darwin. According to today's evolutionary criminologists, crime is a result of the maladaptive process on the social environment. Evolutionary criminological concept wasn't very welcomed by mainstream (positivist) criminologists, but some anthropologist and psychologists still pursue the possibility that crime is a form of an adaptive trait.

Neuroscience and explanations of crime

Rapid development of neuroscience has brought to form of new theories of crime. Neuroscientists point out that crime is a psychopathological or psychological disorder.

Physiological theories of crime are sometimes categorized as psychological theories or biological theories.

William Sheldon, American psychologist in 1949 developed theory of somatotypes. Sheldon made the classification of body types on:
- ectomorphs,
- mesomorphs and
- endomorphs.

Based on the physical constitution, Sheldon found psychological and personality traits, which are characteristic for every of somatotypes. According to Sheldon, ectomorphs are highly predispositioned to commit a crime.

Similar classification of somatotypes was developed by German psychiatrist E. Kretschmer in 1921. Kretschmer's classification system introduced three body types:

- asthenic / leptosomic,
- athletic
- and pyknic.