The notion that our planet and its inhabitants have not remained exactly as the Creator was supposed to have made them was in the air long before 1859, when the English natural historian Charles Darwin collected and published his evolutionary ideas in his great work On the Origin of Species by Means of Natural Selection. By that time geologists had long known that the 6,000 years allowed by the Bible since the Creation was vastly inadequate for the sculpting of the current landscape by any natural mechanism; and the biologists who were just beginning to study the history of life via the fossil record were not far behind them. Around the turn of the nineteenth century, the French zoologist Jean-Baptiste Lamarck began to argue that fossil molluscan lineages from the Paris Basin had undergone structural change over time, and that the species concerned were consequently not fixed. Importantly, he implicated adaptation to the environment as the cause of change, although the means he suggested – subsequently infamous as “the inheritance of acquired characteristics” – brought later opprobrium.

Like every one of the many millions of other organisms with which we share our planet, the species Homo sapiens is the product of a long evolutionary history. The first very simple cellular organisms spontaneously arose on Earth close to four billion years ago, and their descendants have since diversified to give us forms as different as streptococci, roses, sponges, anteaters, and ourselves.

While it isn’t necessary to do so, it’s often good to start a book by saying something that is clearly true. So, let’s do that. Science has had (and continues to have) a significant impact upon our lives. This fact is undeniable. Science has revealed to us how different species arise, the causes of our world’s changing climate, many of the microphysical particles that constitute all matter, among many other things. Science has made possible technology that has put computing power that was almost unimaginable a few decades ago literally in the palms of our hands. A common smartphone today has more computing power than the computers that NASA used to put astronauts on the Moon in 1969! There are, of course, many additional ways in which science has solved various problems and penetrated previously mysterious phenomena. A natural question to ask at this point is: why discuss this? While we all (or at least the vast majority of us!) appreciate science and what it has accomplished for modern society, there remain – especially among portions of the general public – confusions about science, how it works and what it aims to achieve. The primary goal of this book is to help address some specific confusions about one key aspect of science: how it explains the world.

The history of recent wildlife extinctions and the widespread role of humans in these events are described. Conflicting views about the role of human numbers in wildlife declines are cited. There follows an outline of the book structure, highlighting the major proximal causes of declines in Britain , including persecution, urbanisation, agricultural intensification, climate change and disease, as detailed in subsequent chapters. There are also chapters on population growth, people's perceptions of population size and the implications for conservation A comparison of population densities in a range of countries reveals that the UK, especially England, has one of the highest densities in the world. The UK therefore provides an ideal study to investigate the impacts of human numbers on wildlife declines.

Once upon a time it was fair to say that most people knew little of science. After all, scientists spent years learning their job so it’s clearly tough-going and, by and large, the rest of the world could get by knowing nothing of superconductivity or the origins of the universe. But increasingly our daily lives have come to be dominated by science, and part of that revolution has been the ever-expanding reach of television and the Internet as sources of information. It’s as though, unwittingly, we’ve all signed up to the Open University. And, it should be said, when it comes to science this has all been helped by a growing awareness among those in the trade that they have an obligation to let the world know how they while away their days.

Metaphor has traditionally been considered antithetical to science. Metaphorical speech, which is commonly associated with the creative wordplay of poetry and fiction, would seem after all to be at cross-purpose to scientists’ efforts to articulate clear, rigorously precise, and objective statements of fact about reality. Aside from a tendency toward obscurity, the greater problem is that metaphorical expressions are typically false, literally speaking. Shakespeare’s Juliet is not literally the sun, time does not literally flow, and the genome is not a literal blueprint, book, or program. It is principally for this reason that scientists and philosophers of science have been, until rather recently, very critical of the suggestion that metaphor might play a legitimate role in the scientific process. In the early modern period, philosophers like Francis Bacon, Thomas Hobbes, and John Locke, who were enthusiastic advocates of the new scientific approach to understanding the world so brilliantly illustrated by the likes of Hooke, Boyle, and Newton, made withering criticism of metaphor as productive of nothing but falsehood and misdirection.

Why do we1 want to keep anything? Surely it is because it means something to us? Isn’t it because we value qualities like usefulness and the ways in which we can cherish memories and meaningful associations? We may keep things which make life easier, help us in day-to-day living and might assist us in some future difficult time. We may also value those things with enriching associations – something we found on a memorable day; something which appealed to us for its form and beauty, its intricacy, diversity or simplicity; something inherited from an ancestor or given to us by a friend or parent. Or it can be something we did not know about but which we found out about in the media or which a teacher, parent or mentor told us was rare, valuable, a privilege to have. Thus, the meaning can be discovered by yourself or a meaning can be given to you by someone else which then becomes significant to you. Whatever the many reasons for keeping something, it is the value and the meanings which make us cherish it: the meanings vary widely, but meanings there have to be. Hence the subtitle of the book: Perspectives on Meanings and Motivations. Meanings are the key.

When people consider intelligence, they will first tend to think of IQ, and scores that distinguish people, one from another. They will also tend to think of those scores as describing something as much part of individuals’ make-up as faces and fingerprints. Today, a psychologist who uses IQ tests and attempts to prove score differences are caused by genetic differences will be described as an ‘expert’ on intelligence. That indicates how influential IQ testing has become, and how much it has become part of society’s general conceptual furniture.

At the time of writing this book, we have witnessed an extreme case of biological invasion. A virus, through an evolutionary leap, has jumped onto a new host species, Homo sapiens, and has taken advantage of the new host’s ambitions and mobility in the zealous phase of globalisation, causing a worldwide pandemic and economic meltdown. The 2019 coronavirus outbreak (COVID-19) is a showcase of the core of invasion science. A list of questions spring to mind. Why this particular virus, and not others? Why now? How fast can it spread? How is its spread mediated by climatic and other environmental factors? What are its vectors and pathways of transmission? Which regions and populations are most susceptible? How much damage can it cause to public health and economies? What factors cause substantial variation in mortality between human populations in different countries? How can we control it? Can we forecast and prevent future outbreaks of emerging infectious diseases? While the whole world scrambles to make sense of COVID-19 and to combat the biggest crisis for humanity since World War II (WWII), we embark on a journey to address these questions to cover many more taxa and situations – the invasion of any biological organism into novel environments.

There is a long history of describing communities in ecology. It is now time to develop a general predictive framework for this discipline. The goal is to simultaneously provide a consistent theoretical framework to guide research and a practical framework to guide conservation of wild landscapes. We propose that this framework has four key elements: the species pool vector P, the local community vector C, a vector of environmental filters E, and a vector of functional traits T. The central challenge of community ecology is to predict the species composition of any community C, using prior knowledge of P, E and T. Common filters include flooding, fire and herbivory. Each community C is a subset of the regional species pool P and is the result of filtering that matches species’ traits to the local environmental conditions. Dispersal, competition and time are also important in community assembly.