THE GENE
An Intimate History
Siddharth Mukherjee
Penguin
593 pages; Rs 699
The essential you, the essential me and the essential chimpanzee are near-identical genetically. Any two humans share 99.9 per cent of DNA. A human being and a chimpanzee share 98.9 per cent. Those tiny genetic differences create distinct individuals (and make the chimp a member of a different species).
How do genes do this and what do we understand about the processes? This book traces the history of genetic research, from its origins to the (nearly current) state of the art. It is magisterial in scope, and beautifully written as well. As is inevitable, it leaves out detail in certain areas. For example, the new genetic editing technique, CRISPR, is not dealt with.
It has also generated some controversy because some scientists disagree with its representation of epigenetics (the study of heritable characteristics). Mr Mukherjee is also such a facile writer that a reader may not realise the monumental difficulties involved in genetic research and the clever techniques developed for it.
In addition to being a history of science, this is also a potted history of the author's family. He writes with apparent honesty about his family's trials and travails and tensions. In a sombre thread running through, Mr Mukherjee outlines instances of mental illness afflicting three paternal relatives. He writes movingly about his fears that such conditions could affect him or his children. In one brief (and less gloomy section) he also alludes to his mother and her twin sister, while leading into a discussion on twins and their similarities and dissimilarities.
Genetics started with a Catholic monk, Gregor Johann Mendel, who planted peas, and an Anglican student of divinity, Charles Darwin, who went on a long voyage and collected specimens of fauna from South America, including specimens from isolated populations in the Galapagos Islands.
Mendel and Darwin did not know each other. Darwin was probably unaware of Mendel's work. But between them, those two men of God overturned all the creationist myths. Darwin saw the big picture but his hypothesis had some fairly large holes. Those gaps were plugged by referencing Mendel.
Mendel did endless experiments, crossing pea-plants of different characteristics and keeping meticulous records. His data showed how traits were inherited whole, and not "mixed" (given one blue-eyed parent and one brown-eyed parent, a child has either blue or brown eyes, not eyes which mix blue-brown). Mendel also discovered recessive genes.
Darwin spent over a decade sitting on the insights gleaned from his five-year trip on HMS Beagle. He was galvanised him into publication only when he learnt about Alfred Russel Wallace coming to similar conclusions while examining fauna in Asia and Australia. Mendel published in German in an obscure farmers' journal. It was in the early 1900s, after both giants had passed on, that researchers started putting their work together.
The word "gene" was coined in the early 1900s. That was when multiple experiments involving fruit flies, x-rays, climate control and so on offered insights into mutation and survival of the fittest. But the mechanics could only be inferred at that time and an imperfect understanding led to the perpetuation of several horrors.
Literally millions were tortured and killed by the high priests of the pseudo-science of eugenics. The concept of breeding for superior characteristics (and culling undesirable ones) was first mooted by Darwin's cousin, Francis Galton. It was pushed enthusiastically by all manner of racists, as well as by well-meaning cranks. It culminated in the genocidal Nazi programmes.
Meanwhile the Stalinist, Trofim Lysenko, embraced the pseudo-scientific twaddle of Lamarckism. Lysenko pretended to grow wheat in Siberia, and claimed his plants developed resistance to cold and passed that resistance onto their descendants. It was literally illegal to challenge Lysenko's nonsense. Lysenko-ism led to repeated famines and hobbled Soviet science for a generation.
In the 1950s, the quartet of James Watson, Francis Crick, Maurice Wilkins and Rosalind Franklin worked out the famous double-helix structure of DNA with each providing some insights. There have been innumerable major advances since, in gene-sequencing and gene-splicing; in the understanding of how bacteria share data, heritability; on-off switches for genes and so on. The human genome was sequenced quite recently and other genomes including those of our simian relatives, and octopi, are being tackled as you read this.
New insights appear all the time and those insights trigger new moral dilemmas. Gender identity and sexual orientation for instance, are now known to be genetically linked. An enhanced ability to tamper with genes also creates new gray areas. Our knowledge will soon allow us to "build" descendants with "desirable" characteristics like high IQ, regular features, acceptable sexual orientations (whatever those are) and less susceptibility to disease.
Will this lead to eugenics 2.0 with "undesirable" characteristics bred out? Well, Newton probably had Asperger's Syndrome and Alan Turing was gay. What if the genes for high IQ are inextricably linked to such "aberrations" This leads us to philosophical questions about redefining "desirable".
In the end, as Mr Mukherjee reminds us, we are all descendants of the same ur-mother, Mitochondrial Eve. We are also members of a young species, with less genetic diversity than chimpanzees and gorillas. The book paints the history of genetics across a big canvas. It's a fantastic introduction. But it will soon be outdated in some areas because the science is moving so fast. Read it anyway and hope that the next edition will be updated to reflect whatever changes.
