Human beings are amazing. We should never forget that. Not very long ago we stared wide-eyed and barefoot at the Moon; now we can hold Moon rock in our hands. Satellites in orbit let us talk to people anywhere on the planet. We can predict the weather, explore the deepest parts of the oceans, travel at supersonic speeds, perform mind-boggling surgeries, split atoms and comprehend the very fabric of the universe itself. Day-to-day, we are no longer subservient to the vagaries of nature’s rhythms to feed ourselves. No more clad in animal skins, we seldom need to venture out from our tech-heavy, luxurious homes. Slumped on our sofas, phones in hand, we can see the world, meet friends, order groceries and watch the latest movies through the greatest invention of the modern era, the internet. When we live in a world so completely of our own making, and so divorced from the natural environment, it is very easy for us to forget that beneath the blanket of modern life we are just walking, talking apes. We are amazing certainly, but we are also animals, and the twists and turns of evolution have affected us just as surely as every other living thing on Earth.
The great gulf between what we are as people living in the twenty-first-century world we have created and what we were as evolved animals in our natural environment is the central theme of this book. By examining surprisingly diverse aspects of modern life, from our diet to the rise of ‘fake news’, we are going to see that evolution equipped us very well for a world that, for most of us, no longer exists. Rather than helping us, our evolutionary heritage now conspires with the modern world to leave us spectacularly ‘unfit for purpose’. This mismatch between the world in which we evolved and the world in which we now find ourselves has, for example, helped to create an obesity crisis (Chapter 2). It has left many of us unable to consume some important parts of the modern diet without getting ill because evolution hasn’t caught up with globalisation (Chapter 3). Inside our bodies we have developed a very strained and problematic relationship with the important bacteria with which we evolved and on which our health relies (Chapter 4). Meanwhile, the stress response that evolved to save us is now killing us as we pack more and more micro-stressors into our modern lives (Chapter 5). Over the past decade we’ve shifted from having tens of friends to thousands and our brains simply can’t handle the upgrade (Chapter 6). We evolved from a group of unusually violent mammals and we’ve certainly made the most of the legacy with our evolutionary tendencies to lash out creating societies riven by primitive violence (Chapter 7). Addiction, itself a cause of violence, is a result of the ‘potency’ of the modern world hijacking pathways in our brain that evolved to keep us alive but now push us towards a dizzying range of dangerous delights (Chapter 8). As a social animal we have evolved to function in groups, trusting in and cooperating with other people, but social evolution has also shaped us into hopelessly gullible victims of fake news and false beliefs (Chapter 9). Most worryingly, despite a very pressing need to solve the many environmental problems we have caused, evolution has left us selfish and without any sensible notion of the future (Chapter 10). All in all, these mismatches between our evolutionary heritage and the modern environment we have created have left us in a pretty sorry state. To find out how we got into this mess, and perhaps what we can do to get ourselves out of it, we first need to get to grips with the basics of evolution.