The Gene: An Intimate History

Title: The Gene: An Intimate History

Author: Siddhartha Mukherjee

Publisher: Penguin, 2017 (First published 2016)

ISBN: 9780143422167

Pages: 593

Progress of human culture was episodic in various fields of knowledge. The eighteenth century was all about music. The masters of Western music such as Beethoven, Bach and Mozart and the three jewels of Carnatic music such as Thyagarajar, Shyama Shastri and Muthuswami Dikshitar made their profoundest contributions at around the same time. The nineteenth was the century of chemistry and the twentieth, that of physics. Mind you, these are broad classifications and you are not to labour too fine a point on this. The present century, the twenty-first, belongs to biology, especially genetics and genomic engineering. Gene is an entity which encodes a message to build a protein that is further used by the body of the animal or a plant. They are in fact recipes to make the protein, rather than blueprints. A flaw in the blueprint would be quite obvious in the manifestation of the end product. However a defect in the recipe is much more difficult to discern, evident only if you carefully examine the result. Moreover, the genomic effects are influenced by environmental factors and pure chance too. The discreteness and digital nature of genes has made biology much more amenable to methods used by the exact sciences. So far, it was the most lawless of all the sciences. There were few rules to begin with, and even fewer rules that are universal. This era of classification is long past and Siddhartha Mukherjee presents an intimate and voluminous account of the genes to general readers. A highly specialised oncologist of international repute, Mukherjee is the author of the best seller ‘The Emperor of all Maladies’, reviewed here earlier.

It is interesting to examine the weird theories on heredity that was in circulation till hardly a century ago. Ancient Greek philosopher Pythagoras believed that sperm circulated in the human body, collecting messages from each organ and preserving them. Lamarck thought that hereditary traits were passed from parent to offspring in the same manner that a message is passed. This theory held the ground during Darwin's time. By ‘use and disuse’, organs will be strengthened or weakened. This adapted feature would then be transmitted to the offspring by instruction. Even Darwin was erroneous in proposing a scheme for the transfer of traits between parents and their offspring. He imagined that the cells of all organisms produced minute particles containing hereditary information and called them gemmules. These gemmules circulated in the parent’s body. When it reaches the reproductive age the information in the gemmules is transmitted to germ cells such as sperm and egg. The study of genetics fell in the right grove with the analysis of hereditary traits in pea plants by Gregor Mendel. However, his observations were published in an obscure journal in 1865 and remained hidden from scholarly evaluation for 35 years. He found that hereditary characteristics were transferred as discrete bits rather than blended entities.

Mukherjee provides an encyclopedic review of the budding of the science of genetics. Wilhelm Johanssen coined the term ‘gene’ in 1909 as an instrument to store and transfer heredity. Neither he nor the scientific community of that time had any idea of what it was, where it resided or how it operated. The term denoted only a function. By the 1920s, it was known that the gene resided in chromosomes. Research on fruit flies evinced the first hints on the appearance of genetic traits in animals. However, the nascent science suddenly took an unexpected turn for the worse. Eugenics rose as a program to enhance the fitness of a population by sterilizing or even exterminating chronically ill and mentally retarded members of that society. The program originated in the US, but impartial reviews brought out the danger lurking in the details. Anyhow, Nazi Germany embraced it with gusto. The Nuremberg Laws for the protection of the ‘hereditary health’ of the German people was enunciated in 1935. It barred Jews from marrying people of German blood or having sexual relations with anyone of Aryan descent. To plug all loopholes, they were further restrained from employing German maids in their homes. The transition from sterilization to outright murder came unannounced and unnoticed. Genetic courts were set up in the country to order sterilizations. Conservative estimates show that about 250,000 were killed and another 400,000 sterilized.

The book gives a ring-side view of the action in identifying DNA and its structure which led to massive innovation and progress in the field. DNA was discovered way back in 1869 and was called nuclein, because it was found in the nucleus and was acidic in nature. Its cellular function had remained mysterious till 1943, when it was observed that DNA is the carrier of heredity. After Crick and Watson found the double helix structure of it, the pace quickened. Tinkering biologists devised novel ways to manipulate the DNA base pairs and thereby altering the proteins they encoded for production. Recombinant DNA technology was successful in the synthesis of two major proteins very early – Insulin and Factor VIII – for the treatment of diabetes and hemophilia respectively. Earlier, insulin was extracted from the pancreases of dead cows and pigs. Factor VIII, which helped the blood clot, was collected from blood donated by volunteers. A single dose of the chemical required much quantity of blood which was taken from numerous people. In the 1980s, this caused a spurt of AIDS cases in unknowing hemophilia patients who received contaminated injections of Factor VIII. Genetics solved this vexed problem by inserting the required genes into a bacterial genome which made the bacterial cells produce the chemical in its body. It was so clean and so revolutionary at the same time.

After vetting their appetite on fruit flies and mice, geneticists turned their attention to the human genome and controversies erupted. The researchers sought to pre-empt pesky and ignorant lawmakers by self-imposing restrictions in the Asilomar Conference. The Human Genome Project (HGP) reached completion in the year 2000 which was a symbolic reminder of the relevance this new technology signified for the twenty-first century. Any discussion on genes raises the dichotomy between nature and nurture, that is, whether a physical trait is originated only by the chemical pathways of the genome or whether it was also moulded by the environment. The author is the right person to address this query and he gives a mixed verdict. Citing case studies, he points out that genetic factors play a very crucial role in making a person what he is. But, it is not genetics alone. The environment, chemical triggers and pure chance also work on the genotype represented by the DNA in producing the physical manifestations defined by the phenotype. This is held out in a few convincing examples. Schizophrenia and various kinds of cancer are highly hereditary in nature and its genes are carried in the DNA. Identical twins share the same genome. So, if any of the above diseases rear its terrifying head in one of the twins, the other is also ought to succumb to the ailment. However, this is not observed in practice. The incidence rate falls from 80 per cent for some diseases to as low as 10 per cent for others. This argument vindicates the environmental factor.

Mukherjee identifies a new current of novel thought in biology. It is split through the middle. On one side sits its old guard, the natural historians, taxonomists, anatomists and ecologists who were pre-occupied by the classification of animals and qualitative description of organisms’ anatomy and physiology. The other now studies molecules and genes, common mechanisms and the secret of life. The author rubbishes the notion of stigma among individuals having a history of highly heritable diseases by openly discussing the many instances of mental disease running in his own family. This increases the confidence level of such persons and initiates a wave of empathy towards the author. The book also shares some anecdotes on how genes played with the history of nations. A case in point is that of the czarist prince Alexei, whose genetic illness of hemophilia and general emaciation was also a factor in the violent overthrow of the Russian monarchy in 1917.

The book is exhaustive, but without being exhausting to the readers.

The book is highly recommended.

Rating: 4 Star