Crime Zero Read Free Page A

brain, and understanding these differences is pivotal to understanding the small subset of criminally violent males. A chemical mixture of neurotransmitters and hormones drives the brain. Let me deal with neurotransmitters first. They are the chemical messengers controlling the flow of electrical messages in the network of nerve cells that allow the complex neural networks of the brain to communicate with one another. They influence and facilitate the thoughts of our mind and the actions of our bodies.
    "There are four key neurotransmitters. Three of them-- dopamine, adrenaline, and epinephrene--are very similar. They fuel the brain, stimulating many of our emotional and physical impulses, such as the fight or flight reflex. The fourth is serotonin; this is the vital brake that inhibits and modifies our waking behavior. Its specific function is to link the impulsive limbic part of the brain with the more civilized cortex. Put simply, without serotonin we would have no conscience or inhibitions.
    "While neurotransmitters are responsible for the instigation of specific actions, hormones influence the broad pattern of behavior, although the interaction between them is complex. Again put simply, the higher the level of androgens, particularly testosterone, the higher a man's aggression and the lower his empathy with the pain or feelings of others."
    Nodding, Latona stepped in. "So overall the male brain is more specifically wired and fueled for aggression, impulsiveness, and crime than is the female brain. But this doesn't mean that all men are violent criminals."
    "Of course not," said Kathy with a wry smile. "Violent criminals are the small minority of men well outside the norm, for whom these natural differences have become amplified, exaggerated. There exists a range of physiological tests on which they can be reliably assessed versus the norm. For example, we can measure in the blood levels of MAO, an enzyme that acts as a marker for the neurotransmitter serotonin. And we can monitor levels of brain activity with PET scans and electroencephalograms--"
    "OK," interrupted Latona. "So violent criminals are physiologically different. But how exactly does genetics fit into this picture?"
    "The recent invention of the Genescope has enabled scientists to read an organism's entire sequence of genetic instructions. By conducting aggression studies on primates, my team and I have identified seventeen key genes that code for the production of critical hormones and neurotransmitters in male primates, including humans.
    "These interdependent genes effectively determine man's aggressive behavior. And depending on how each gene's promoter, or volume control, is set, we can tell how loudly that gene will express its instructions. For example, we can predict dangerously low levels of serotonin or high levels of testosterone by studying the calibration of these genes. What we have discovered is that although everyone's gene settings change in reaction to particular stimuli, almost every individual has different base settings. If you see these seventeen key genes as cards, then every man is dealt a slightly different hand."
    "Is it true that although this work was done originally on apes, it is now relevant to humans?" Latona asked.
    "Yes, much of my recent work confirms these findings in men."
    "So a man's genes determine if he is going to become a criminal or not?"
    "To an extent. But I stress what I said earlier. Environmental, social, and cultural factors also have an influence. However, the crucial point is that humans are different from animals because they possess consciousness. This means that they are aware of the consequences of their actions. So regardless of any genetic predisposition, free will still plays a significant part in the choices humans make. But certainly some men, regardless of other influences, will find it more difficult than others to behave as society expects them to. The genes they inherited from their parents give