text: Criminology is the systematic study of crime and its prevention. Criminologists apply themselves to difficult questions such as, "Why does crime occur?" Among the answers that they have come up with is that crime springs naturally from the biological nature of certain individuals. This biological theory of criminology has a very long history, but it stood on shaky evidence for a long time.
  In the 1800s and the 1900s, people who believed in the biological theory of crime claimed that some people are inferior to others and should not be allowed to reproduce. The evidence that they relied upon was of very poor quality, but many Westerners agreed with them.
  Today, the biological theory of criminology is seeing a resurgence thanks to neuroscience, or the study of the brain. As scientists get a better understanding of how the brain works, they are able to see the links between certain chemicals in the brain and crime.
  Criminological theories have a long history, but biological theories of crime are rather new. They can be traced back to the work of Cesare Lombroso, an Italian criminologist who was most influential in the late 1800s and early 1900s. When Lombroso entered the field of criminology, most of his colleagues focused almost exclusively on the legal aspects of crime. They wanted to discover the combination of laws that would reduce crime.
  Lombroso changed that forever. Instead of focusing on the law, he focused on the criminal. Lombroso thought that some people are more primitive than others - they are living relics of an earlier stage of human evolution. These primitives can be identified by their strange skulls, and they are more prone to violence.
  Some people took up Lombroso's theories to argue in favor of eugenics, or the elimination of certain bloodlines from the human species. During the Progressive era in America, eugenicists gave highly publicized speeches and wrote books that influenced state-level legislation. Many had a definite racialist tinge. So did the claims of Nazi eugenicists of a later period.
  Of course, these biological theories of criminology were disproved within several decades. However, Lombroso had a lasting impact on the field. In addition to shifting the focus from the law onto the criminal, Lombroso promoted the humane treatment of prisoners, arguing that work programs could teach them valuable skills and help them return to normal society.
  Today, there are two main types of the biological theory of criminality: the genetic approach, and the neuroscientific approach.
  Genetic Influence on Criminology
  Those who argue that there is a genetic influence on criminology often conduct research on twins. These twin studies are very useful because identical twins share 100% of their genes. The twin study literature does show that there might be something to the biological theory of crime.
  For example, if one twin commits a crime, the second twin is more likely to commit a crime, even if the twins do not live together. Geneticists have been trying to find a specific gene, or genetic sequence, that could predispose someone to criminal behavior. Some have proposed that a "warrior gene," MAOA (monoamine oxidase A.), could be linked to violent behavior.
  While the search is on for specific genes linked to criminal activity, one genetic factor is undeniably linked to the vast majority of violent crimes. In fact, about 75% of violent criminals share this trait. That's because 75% of violent criminals are men, endowed with Y-chromosomes.
  Neuroscience and Criminology
  Starting in the late 1900s, the biological theory of criminology got a big boost from the new field of neuroscience. Advanced research technology enabled researchers to identify structural and chemical differences in the brains of criminals and law-abiding citizens.
  Scientists in the field of neurocriminology often focus on looking for abnormalities in a person's brain that lead to criminal behavior. From time to time, they are asked to provide expert testimony in court cases. This practice is accompanied by some controversy.
  Whenever a criminologist tries to explain crime through reference to biology, they are using a biological theory. For example, it is widely accepted that the people most at risk of committing crimes are young men between the ages of 18 - 25. Crime statistics make this abundantly clear, and neuroscience confirms that the parts of the brain associated with impulse control are not fully developed until after age 25.
  Like all scientific theories, criminological theories are hotly debated. However, unlike physics or mathematics, criminology can have a huge influence on people's lives. That's because criminological testimony can lead to a defendant receiving a light or harsh sentence.
  Some argue that biological theories of crime can be used to absolve people of responsibility for their actions. In court, an eloquent attorney can argue that their defendant "couldn't help it" because of their genetic inheritance, and should be treated differently than others as a result. This has led a philosopher to sarcastically propose that men should receive lighter sentences than women because they are "genetically predisposed" to crime.
  However, in some cases, people with brain tumors have suddenly become violent or displayed perverse sexual behavior. When their tumors have been removed, their behavior has returned to normal.
  Biological theories of criminology date back to the 1800s when Cesare Lombroso made them famous. Originally, they claimed that criminal behavior was hereditary, due to the existence of "primitive" elements in some people's lineages. However, during the 1900s, both genetic and neuroscientific evidence showed that there is definitely a biological aspect to criminality. However, many people feel that biological theories of criminality absolve people of their personal responsibility for a crime.
  In twin studies, geneticists have found that there seem to be some genetic influences at play in criminal behavior. For example, if one twin commits a crime, the second twin is more likely to commit a crime. Similarly, work in neurocriminology has established a link between certain brain structures and chemicals, and criminal behavior. Though some theories remain controversial, one thing is clear: men are far more likely to commit violent crimes than women. This indicates that there must be some link between the Y-chromosome and violent criminality.
  Laura is really interested in what makes people different from each other. She has noticed, for example, that some people are really tall and others really short. Some people are really outgoing, and others are more shy. And she's noticed that some people end up committing crimes and others obey the law. Laura wonders what makes people different from each other, and more specifically, she's recently been wondering why some people commit crimes and why others don't.
  Criminology is the study of crime and punishment. It tries to answer questions like, ''What makes people commit crimes?'' There's no simple answer to that question, just as there isn't an easy way to know why one person is outgoing and another is shy. But one theory of criminology stresses the biological differences between people and how that might affect their predisposition to commit crimes. Let's look closer at that theory.
  Laura has noticed that some people end up in the criminal justice system, while others don't. She wonders what makes them different from each other. Is it possible that, like how tall you are, some people are just destined to engage in criminal activity?
  Cesare Lombroso wondered the same thing in Italy in the 19th century. He was one of the founding fathers of the biological theory of criminology, which says that individuals who engage in crimes are biologically different from their peers. Today, Lombroso's theory is being explored in two major areas: genetics and neuroscience.
  The mapping of human DNA has brought new information and also new questions to scientists, and just as many scientists are looking for the specific gene that can cause certain diseases, some are looking for the one gene that could cause criminal activity.
  From twin studies, there does seem to be some sort of genetic influence. For example, some studies have shown that identical twins raised separately are more likely to both engage in criminal activity than non-twin siblings raised separately. Since identical twins share all the same DNA but other siblings only share part of their DNA, this indicates that perhaps there is a ''law-breaking gene'' somewhere in the human body, but so far, scientists have not found it.
  The second area that the biological theory of criminology is exploring is that of neuroscience, or the study of the brain. As brain imaging techniques become more detailed and less invasive, scientists are getting better and better at mapping the human brain and discovering differences in people's brains. So far, studies have shown that there are some structural and chemical differences in the brains of individuals who break the law when compared to the brains of individuals who obey the law.
  For example, one study showed that people who commit crimes have less activity in the part of the brain responsible for arousal and fear. The theory is that they feel less fear of consequences, and so, they act out in irresponsible ways.
  Wow! Laura thinks that the biological theory of criminology sounds pretty solid. After all, who is she to argue with scientists who are finding brain and genetic differences in people?
  Well, not so fast, Laura. Though there is compelling science behind the biological theory of criminology, there are some shortcomings, too. For one thing, there used to be other biological theories, which have been discredited. For example, in the late 19th century, it was common for people to believe in phrenology, or the pseudoscience that said that people's personalities could be mapped according to the shape of their head. Phrenologists believed that certain skull bumps and ridges could indicate that a person was biologically disposed to engage in criminal activity. Since then, that has been debunked, but it makes Laura wonder if the science of today might also be debunked one day.
  Another shortcoming of the biological theory of criminology is the fact that it does not provide causal evidence. That is, it cannot tell us if the biology causes the criminal activity or if the criminal activity causes the biological differences or if something else causes both of them.
  Think about it like this: We can say that individuals who may break the law have a specific biological abnormality, like less activity in the part of the brain that causes fear, but not every individual has that, and not everyone who has that symptom may break the law. So, we don't know what's causing it or why sometimes it matters and sometimes it doesn't.
  One final shortcoming of the biological theory of criminology is that it absolves people of responsibility for their actions. If a person commits a crime and then says, ''But it's just because my brain is wired differently'' or ''It's because I have a law-breaking gene,'' then they are not taking responsibility for their actions. This has caused a debate in the criminal justice system as some defendants argue that they should not be found guilty because their biology caused their crime. As scientists uncover more data about the influence of biology on crime, this debate will likely continue.
  Criminology is the study of crime and punishment. The biological theory of criminology says that individuals who commit crimes and individuals who obey the law are biologically different. Today, it is focused on two major areas: genetics, as scientists look for the specific gene that might predispose someone to crime, and neuroscience, as scientists look for brain differences between criminals and non-criminals. Though there is evidence that there are some biological differences, there are some shortcomings of the biological theory of criminology, including the fact that some biological theories, like phrenology, have been discredited. Biological research does not provide causal evidence, and the biological theory absolves people of responsibility.
  After completion of this lesson, you should be able to:
  - Describe the biological theory of criminology
  - Understand the two major areas of biological study that use this theory
  - Summarize some of the evidence that supports this theory
  - Identify the shortcomings of the theory
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  The main idea is that crime has a biological basis. This may be genetic, or it could have to do with the age of the criminal.
  One example would be the theory that men between the ages of 18 and 25 are more prone to violence because of the stage of their brain development. This explains crime through reference to biology.
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