You need to look beyond genes (genotype) to understand human behavior (phenotype). Today, evolution is not only trying to answer how nature and organisms form and develop; but also it considers development and change of human behavior in hundreds of thousands of years. The original version of the article presented below was published in a Turkish magazine, named NTV Bilim, in March 2009. Thanks to Istem Fer, who translated the document into English, giving me a good reason to share it with the beloved followers of CounterMinds! Enjoy!
In Rocky IV (1985), before the final match between Rocky and his opponent Ivan Drago begins, Drago’s manager quotes: “It is the size that matters. Doesn’t evolution say so? Drago is the best-trained boxer you have ever seen. There is not adequate muscle, strength and genes in that man [Rocky] to win. It is physically impossible for that little man to win!”
However, the end is known; our aggressive hero Rocky whose genes are “so called” incapable, knocks genetic wonder Drago out in the ring just by training in the wild!
It might have not occurred to you that Rocky had delivered the world of genetics a hard blow when he knocked out his gigantic opponent who had far stronger genes than he does. But as a scientist who is interested in evolution, when I saw this scene what came to my mind was that Rocky did not only win a victory over USA’s eternal rival Soviet Russia, but also he slapped scientific world who is trying to find an answer to the question whether genetic or environmental factors are more dominant in the development of individuals.
It is not sufficient to look their genes to understand human behavior. Today, evolution is not only trying to answer how nature and organisms form and develop. Evolutionary biology is a broader field that covers human behavior, development, and changes in hundreds of thousands of years, health and medical science. Such that when evolution tries to find an answer to the “Do genetic factors beat environmental factors?” question that I mentioned above and examine organisms’ behaviors, it wants us to distinguish genetic and environmental factors. So, how do we explain the origin of behaviors such as aggression? Let’s listen aggressive people’s excuses from evolutionary genetics.
The genes mao-a and mao-b (monoamine oxidase) in mammals are just the two of the genes that are responsible from aggressiveness. In our evolutionary history, mao-a and mao-b genes are formed by duplication of a single mao gene in the period of transition from aquatic to terrestrial environment. These two genes are responsible from the production of MAO A and MAO B enzymes. These enzymes react with the hormones that can affect mood like serotonin, dopamine and norepinephrine inside our bodies, especially inside nerve cells. In short, the chemical balance of our mood is inside these two enzymes’ hands. Therefore things change as the balance of these two enzymes’ is spoiled.
Think of it this way: hormone construction and deconstruction continuously goes on in our bodies and these two enzymes are responsible for balancing the hormones. However, as we get older, MAO B enzyme’s activity increases and our cells start to react with more hormone than usual. This changes body’s hormone balance drastically. That’s the reason why we are becoming more aggressive as we get older! If only, the only result of this imbalance was aggressiveness: uncontrolled MAO B could lead to permanent nerve diseases such as Parkinson and Alzheimer.
Another enzyme, in the intersection of evolution and behavior science: MAO A, alone and proud. The gene where to look in order to understand the aggressiveness and anger in males is mao-a. Studies show that, men who have an inherited point mutation in their mao-a gene are aggressive and have a warrior soul. The striking point of the study is this: The men who have a healthy family life in their childhood would not be affected from this mutation in their genes. According to a survey amongst a group of prisoner men, the ones who both have this mutation and an unhappy childhood appear to be more inclined towards violence.
How about women? Mao-a gene is on the X chromosome. Remember that women have two X chromosomes; even there is a mutation in one of them, the other X chromosome can compensate this defect. As it can be seen, the ones who are paying the penalty of this genetic defect are the men who have to content with the only one X chromosome they have.
Why MAO A and MAO B? Why there is not only one enzyme instead of these two very similar enzymes? Why did natural selection let them be? Remember that MAO A and B were split off from just one MAO. The enzyme, which is one in number in aquatic vertebrates, duplicated in transition to mammals? What features does Ancestral MAO show when it is compared with modern enzymes? Is it possible for some other enzymes like MAO C and MAO D to appear? Or do they exist yet we are not aware of them?
Just as Rocky’s victory over his genetically superior opponent Ivan Drago, maybe the aggressiveness that depends on both genetic and environmental factors affected the balance between individuals. The individual who does not appear to be very strong may gain the power to overcome his rival with aggression and passion. With this manner he may have adapted to the environmental conditions and despite of being genetically defected, by starting (and protecting) a family, he might have resisted natural selection and maintained his kind. Understanding how and why these enzymes originated, without a doubt, is a big step to take them under control.
Evolutionary studies seem to teach us lessons about why it would not be fair to judge people just by looking into their genes, what do you think? There is no genome without error, love me with my mutation!
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