A Random Walk in the Jungle of the Gene 

A Review on The Gene: An Intimate History by Siddhartha Mukherjee  

Summer 2023

The genetic code records not only the gene mutations and recombinations that an individual experiences throughout their life but also the gene mutations and recombinations that their ancestors have undergone over thousands of years. Although most of the inherited gene fragments become inactive, some may only be temporarily inactive due to chemical markers and proteins. When an individual encounters the same environmental factors faced by their ancestors, certain corresponding fragments can be reactivated. Once activated, these genes may then be passed on in an active state to the next generation.

Throughout life's journey, individuals are constantly exposed to environmental stimuli, and their genes continuously mutate and activate/deactivate. People often know little about their own genes, as if they are wandering in a dark jungle, occasionally kicking some stones. These small stones roll and touch other things in the genetic jungle, triggering unpredictable chain reactions. Although unpredictable, these chain reactions are almost programmatically recorded in the individual's genes. In other words, some individuals who kick the same stone may not trigger a chain reaction, while others almost certainly will.

The encounter between an individual and a stone is random, but the chain reaction it triggers is fated. This kind of random fate often leaves people confused and helpless. Especially in the case of some genetic diseases, the onset of symptoms seems so random, but the deterioration of symptoms is so determined as if predestined by fate. This is the random fate that genes bring to individuals.

Absolute fatalism is disheartening, but a more seemingly random fate is invigorating. If one can establish the link between random environmental factors and fated chain reactions, and better understand their own genes, they can prevent themselves from being exposed to these random environmental factors to avoid harmful chain reactions.

Identity Cognition: Who Am I, Where Do I Come From, Where Am I Going?

These three philosophical questions are often used to explore the meaning of life. Traditional fatalism is just one way to answer these three questions. There can be many answers, and believing in fate is not entirely absurd. After all, perhaps random fate is the biological answer to these three questions. However, we do not intend to discuss the correctness of each answer but want to clarify that the ways to obtain these answers are already different from the past.

In the past, the meaning and value of life were usually generated based on social and cultural understanding. For example, Marx believed that man is the sum of all social relations. But now, as people's understanding of genes deepens, the exploration of the meaning and value of life should not only be based on social and cultural understanding but also on an understanding of the individual's biological basis, i.e., the understanding of their genes. The extent to which genes shape character and talent exceeds people's imagination. For example, people with Down syndrome tend to have more docile personalities. In some gene fragments of these individuals, certain mutations regulate their character. Life's journey is a process of self-understanding, and in this process, understanding one's own genes is becoming increasingly indispensable. Using scientific means to answer philosophical questions is an opportunity that this era offers to every individual.

All People Are Born Equal: Every Gene Mutation Is Equal

Evolution has direction, but gene mutations do not. The sad truth for individuals is that no matter how hard they try (such as training their physical and mental abilities), the gains obtained through training cannot be encoded into their genes and passed on to the next generation. But at the same time, this fact is also a kind of luck. If gains obtained through social effort could be inherited, then Social Darwinism would have a genetic basis. However, the cruelty towards the weak and the worship of the strong in Social Darwinism are not a reflection of the real world nor a perfect world. The deepest compassion of human nature is at odds with Social Darwinism. Perhaps, the basis of human compassion lies in this genetic fact — every mutation is equal. For example, the memory mutation that causes Down syndrome is no different in substance from the gene mutation that increases human intelligence. They are both random. Therefore, intelligent children are cherished, and children with intellectual disabilities due to Down syndrome are also deserving of compassion.

From this perspective, if humanity has only one optimal evolutionary strategy, it is not "higher, faster, stronger," nor is it "smarter, more efficient". This optimal strategy can only be to preserve greater genetic diversity. The significance of this on a societal level is inclusiveness towards different races, cultures, social structures, customs, etc. Because behind these is the mirror image of genetic diversity. All men are born equal because every genetic mutation in us is equal.

Views from the Book

1. Humanity migrated from Africa to other parts of the world. African genetic diversity is richer than that of other populations around the world. The reason lies in the fact that with each migration, only a small portion of the genes were carried away. Africans not only retain all the original genes but also accumulate mutations over the long years that fundamentally ensure their genetic diversity.

2. The c-myc gene is like a switch that controls whether mature specialized cells can revert to embryonic stem cells. This gene is like a switch that can stop aging as if humanity is on the verge of eternal youth. But this gene also controls cell proliferation, and unlimited proliferation means cancer. The most sinister disease and the most beautiful vision are unified in the same gene. The unity of contradictions is always fascinating.

3. "All diseases are genetic diseases."