Biological differences in human personality also account for criminality in human beings. The logic behinds biological explanation of crime is that structure determines function and persons behave differently owing to the fact that they are somehow structurally different. The physical and biological abnormalities are generally responsible for criminal behaviour. In other words, the criminal is viewed as biological organism characteristically different, abnormal, defective and inferior, both biologicallyand physiologically.The physio-biological explanation of criminal behaviour inspired Pro. Franz Joseph Gale to develop the doctrine of phrenology relationship between head conformation and personal characteristics of a person. He first published his work on this topic in 1791. His disciple John Gapser Spurzheim carried this doctrine to England and United States in early twenties of nineteenth century.An American criminologist Dr.Caldweel showed keen interest in phrenology and published his 'Elements of Phrenology' in 1824. The doctrine underlined three basic propositions :-
i) the exterior of skull conforms to interior, and to the shape of brain;
ii) the mind consists of faculties;
iii) these faculties are related to brain and skull.
Dr.Caldweel emphasized that sentiments control the propensities and are aided by will to govern the whole conduct or act of a person. Thus 'will' and 'spirit' were supreme in controlling the human behaviour. The theory has, however, been disapproved being purely hypothetical in nature and has now fallen into disuse.
Bio-chemical researches tired to show that hormonal imbalances have an adverse effect on criminality. In other words, hormonal imbalances affect the thinking power of brain and control over nervous system and this may lead to criminality. But the general consensus does not accept these findings. The more accepted view is that hormonal imbalances may act as catalyst for criminal behaviour and provide a favourable biological environment for crime causation but criminality cannot be attributed to these imbalances alone. However, imbalance in sex hormones does affect human behaviour. Particularly, great hormonal changes usually occur in woman just before and during menstruation period commonly referred to us as PMT and MT.
Likewise, physiological factors such as age, sex and certain endoctrinal imbalances also seem to have a correlation with the criminality of offenders. Adolescents and juveniles are more prone to offences like stealing, vandalism and sexual assaults as they readily fall a prey to the urges of sex and other lustful activities because of their tender age. The offences of theft, gambling, drunkenness, breach of traffic rules etc., are more common with young persons who are normally between the age group of 18 to 30 years. This is probably because of the fact that these offences involve considerable display of courage, boldness and adventure which these young persons normally possess. Persons advanced in age and experience are more prone of offences like white collar crime, fraud, cheating, embezzlement etc., because the nature of those crimes require maturity of mind and tact to handle intricate situations is case of detection.
Md. Shahnewaz Zwaki Advocate The Supreme Court of Bangladesh (High Court Division).