Daniel M. Davis - The Secret Body: How the New Science of the Human Body Is Changing the Way We Live

Daniel M. Davis is Professor of Immunology at the University of Manchester and author of two previous books: The Beautiful Cure, shortlisted for the 2018 Royal Society Science Book Prize and a book of the year in The Times, Telegraph and New Scientist, and The Compatibility Gene, longlisted for the 2014 Royal Society Science Book Prize and shortlisted for the Society of Biology Book Prize. His research, using super-resolution microscopy to study the immune system, was listed in Discover magazine as one of the top 100 breakthroughs of the year. He is also the author of over 140 academic papers, collectively cited over 13,000 times, including articles in Nature, Science and Scientific American.

A lso by D aniel M. D avis

The Compatibility Gene

The Beautiful Cure

To Katie

Come with me

On a journey under the skin

We will look together

For the Pan within.

The Waterboys

Human biology is a vast realm of science. None of it the journey, the knowledge or its implications is simple. I can only apologise to anyone whose work I have not included or mentioned all too briefly. Every discovery involves many students, postdocs, colleagues and collaborators, and at some level every scientific achievement is owed to a community. I apologise especially to anyone who played a role in the work I discuss here, but have not named. Through interviews with many scientists and my own reading of the original research I have sought to describe how advancements were made, but any one book can only tell part of a story. For that, I apologise in advance too. Finally, I have changed a few details in the medical stories I present in order to conceal some peoples identities, but everything else of those stories is accurate and true.

Imagine yourself as an alien with an exceptionally powerful telescope trying to understand what happens on Earth. You come across a soccer match, but your telescope isnt powerful enough to see the ball. You can make out a pitch with goals at each end, and players moving about, seemingly with some sort of organisation, but its hard to understand what is happening precisely. You publish the observation in the Alien Journal of Earth Science. A few other aliens email you congratulations, but only a few.

In time, alien telescopes improve, and then occasionally you see one of the players in front of one of the goals fall over. Sometimes this is followed by the crowds of people around the pitch waving and cheering. It still doesnt make much sense, but leads to discussion at the bar during the Alien Congress of Earth Science, and your research funding is renewed. Eventually, when you are much older, a younger alien working with you notices something especially intriguing. When the player in front of the goal falls over, whether or not the crowd cheers seems to depend on one thing: whether or not the net bulges outwards. This leads your younger colleague to have a brilliant idea.

While others might have dismissed the observation without thinking very deeply about it, she wonders if there might be something there which causes the net to bulge a ball but its just too small to see. At first you dont believe her, but the idea grows on you. With a ball, everything else starts to make sense: the movements of the players, the net, the cheers, the whole game, and in time other aliens agree, there has to be a ball there. Even though nobody can see the ball directly, everyone agrees its there because so many things make sense if it is. You, your colleague and the alien who invented the super-powerful telescope collect many prizes, and everyone wants to be your friend.

Alien telescopes might improve again so that the ball is eventually seen. But equally, this might not happen. A heavy weight of evidence suggests the ball is there, but there may be no direct proof. At some level, its debatable whether anything can ever be proven absolutely: there is no way of proving the sun will rise again tomorrow, just a heavy weight of evidence that says it will.

This tale of aliens and sport reflects how many discoveries are made. Take, for example, the discovery of the planet Neptune, first seen in 1846. The movement of another planet, Uranus, had been carefully tracked, and mathematical calculations showed that it didnt quite follow a simple orbit around the sun. This could be explained if an unseen planet was pulling on Uranus to influence its path. British and French astronomers calculated where such a planet would have to be located if it were to account for the distortion in the movement of Uranus. Then, with a telescope pointed precisely at the predicted place, the new planet was seen Neptune. Today, a substance called dark matter and a force called dark energy are predicted to exist in order to explain the movement of stars and galaxies. As yet, both remain unseen.

Throughout almost all of history, most wonders of the human body have been hidden from view and barely imaginable. Some of our inner anatomy bones, muscles and a few major organs has always been available to scrutiny (albeit with a bit of delving beneath the skin), but the vast majority of our bodys secrets have, until relatively recently, been the stuff of hypothesis and speculation. The discovery of cells made possible by the invention of the microscope in the late seventeenth century presaged the beginning of our modern understanding of human biology, and the discovery of the structure of DNA in the middle of the twentieth century was another gargantuan step forwards as it revealed how genetic information is stored and replicated. Most recently, however, a whole series of technological and scientific revolutions have taken place that are revealing hidden landscapes within the human body as never before confirming some hypotheses, undermining others and, above all, leading to a whole new realm of possibilities, both theoretical and practical.

What we are learning is that the human body is a world full of other worlds. Every organ is a menagerie of cells, and each cell has its own inner cityscape of scaffolds, capsules and monorails, all fabricated from a bewildering array of biological building materials: proteins, sugars, fats and other chemicals. Our raw materials are nothing special oxygen, carbon, hydrogen and a sprinkling of other elements but, put together in an exceptional way, these raw elements create a body that is conscious, self-healing and capable of poetry. We know of nothing else quite like us in the universe; there may be nothing else like us in the universe. Surely nothing can be more profound or enlightening than understanding how we work. And new instruments and tools, from microscopes to complex data analytics, are providing this understanding by peeling back layers of the body like never before.

Of course, all science has an ever-increasing impact on our lives, but nothing affects us as deeply or as directly as new revelations about the human body. There are any number of examples: analysis of our genes presents a new understanding of our individuality; the actions of brain cells give clues to how memories are stored; new structures found inside our cells lead to new ideas for medicine; molecules found to circulate in our blood change our view of mental health.