Mark Pagel on the past, present and future of the genome
In Jacob's Ladder: the History of the Genome Henry Gee tells the remarkable story of how an inanimate and nearly inert molecule directs, on its own, the assembly and maintenance of the most complex machine on Earth. That machine is of course the human body, and the molecule is our DNA. To grasp the enormity of this feat, consider for a moment what must be accomplished to make a body. Two small inchoate cells a sperm and an egg unite to form a single cell called the zygote. There isn't anyone there no homunculus, no deus ex machina to tell them what to do next. But with almost unerring reliability they do take the next step and the next and the next, by successively dividing to form two cells, then four, then eight, and so on, eventually producing the trillion or so that make up a fully formed body.
Sounds easy just divide. But how do the cells know what to do? Some will become teeth, others bones, others red blood cells, others brain cells or parts of your finger; others yet become your kidney or your ear, even though all descend from the same single amorphous cell. They all end up in the right place, and the finished product makes the Space Shuttle seem like a Lego toy it has lots and lots of pieces but not a huge amount of complexity (and remember, Lego toys and Space Shuttles come with instructions). This is the, well, miracle of development and it is the subject that Henry Gee writes about so agreeably in this book.
Gee in fact tells three stories. The first is a nearly momentbymoment account of the development of a single fertilized egg into a fully formed foetus, ready to emerge from its mother. Even hardened biologists, upon grasping the complexity of development, often shake their heads in disbelief, looking skywards for a creator. Gee somehow glides through the complexity, making the story almost poetic, and, more to the point, plausible. Read this account of development even if you never thought you would read a book about biology.
Gee's second story traces how our genome records the entire 3.8 thousand million years or so of the evolution of life on Earth. The 'history of the human genome' is really the history that is written in our genome. We share ancestry (roughly in order) with apes, monkeys, rats, cows, armadillos, kangaroos, birds, lizards, fish, dinosaurs, insects, plants, fungi, and bacteria, and little bits of each relative can be found in our genome, still firing away to make some bit of us or other, just as they have for eternity. This is Darwin's 'grandeur' of life, ably informed by Gee's grasp of the science of molecular biology.
The final section of Jacob's Ladder reflects Gee's day job as an editor for the weekly science journal Nature. In that job Gee has a front row seat watching the latest and best research in biology. And what a seat that must be, as over the last seven or eight years, biological science has advanced at a speed that no one would have predicted and which can be terrifying for those trying to keep up. Fields that didn't even exist as little as five years ago have already pushed the recently glamorous field of genomics (the study of what is in our genome) into a mere supporting role. One of these new fields is proteomics, the study of how the possibly hundreds of thousands of different proteins that are the products of our genes, combine and interact to make our cells, how cells interact to make organs, and how organ systems combine to produce bodies.
Proteomics is the Jacob's Ladder of Gee's title. He has correctly appreciated that the deep and lasting impact of this century's biology will be a godlike power to alter, modify, combine and, yes, even to create new life forms. We are poised like archangels on the brink of being able to direct our own development. If this seems bold, be assured that Gee has no truck with scare stories or extravagant claims. Jacob's Ladder is an engagingly written and informed account of what is probably the most important science of our times.
Jacob's Ladder is available from Amazon (UK)