Book Summary: Genome by Matt Ridley

The time scale of evolution is very wide, it is scaled not in years but millions of years. Life came into being in the oceans as single celled creatures billions of years ago. They got evolved into multi-cellular organisms and into fish and amphibians. Few species deviated to be transformed into reptiles and plants. That took millions of years. Evolution further led to creation of birds and mammals and at last, came the human beings. That was 2 million years ago. In the time scale of evolution which spans a few billion years, 2 million years is a short span of time. As life transformed from one form to another, its genetic structure got modified to preserve and propagate the changes as new species.

 

Though our immediate cousins were Chimpanzees with whom we share 98% of genes, our common ancestor departed from other mammals a few hundred million years ago, so we share 80% of our genes with cow. Before we were mammals, our ancestors were birds and fishes, so we share 60% to 70% gene pool with them. Even before our ancestors we were animals, they were plants, so we share roughly 50% of genes with apple and banana.

 

Though majority of Genome (complete set of genes) is shared across life in this Universe, what makes each plant/animal unique is the minor difference in its gene pool. Chimpanzees have 24 pairs of chromosomes (which carry the genes), that is how they retain their uniqueness. In humans, it is 23 pairs of chromosomes. We get one set each from our father and mother and they together as a pair provide the necessary instructions for us to grow into an individual human being. Each chromosome, having a set of genes together, influences the anatomy of our body, its functions and the behavior. Some take care of growth of physical organs as we grow into adulthood. Some take care of bodily functions like digestion. Few are responsible for repair from injury and regaining health from sickness. Few prepare us for reproduction when we reach sexual maturity. Few genes instruct our cells to decay and die. Some genes influence our behavior too.

All of these instructions are packed into genes in a language with just four letters (A, T, C, G). and each letter is a chemical. Together, they have the blueprint of our physical body and govern its functions as well. While the scientists have seen some success in decoding this language, our understanding of it is not yet complete. But whatever we have understood so far is mesmerizing. All the learnings from a billion years of evolution is packed in the form of genes and as we understand them better, our understanding of ourselves get better too.

This book, in its 23 chapters, investigates how genes on each chromosome governs what happens within our bodies. Some of the genes influence our behavior and they are in turn influenced too with our behavior. It is a 2-way street. Our food intake, lifestyle, age, stress on body and mind, all lead to switching on or off some of the genes which in turn help us recover from illness or succumb to a disease.

 

Though I had attempted reading this book twice in the past, I could not digest or appreciate it. In the last few months, I had put efforts to improve my understanding of molecular biology, read many books on the subject, watched videos and listened to podcasts. And the third attempt to read this book kept me engrossed for a week. I could appreciate it this time and write a book summary.