Since the Greeks, our world has been understood in terms of one of two root metaphors – the world as an organism (“organicism”) and the world as a machine (“mechanism”). With the coming of evolutionary ideas in the eighteenth century, we see that there are interpretations in terms of both metaphors.

For a book that attempts to explain how to understand visuals in life sciences, it seems prudent to first explain what we mean by “visual,” even if it may seem quite a common word.

In everyday conversation, “visual” is often used as an adjective and means “relating to seeing or sight,” as in “visual impression” or “visual effect.” In the context of this book, “visual” is used similarly as an adjective, but in addition, and more often, it is used as a noun. As a noun, it refers to the variety of images used in life science communication. For example, photographs are a type of visual commonly used in life science communication, and so are drawings.

The theory of evolution, as espoused by Charles Darwin in The Origin of Species in 1859, was difficult to accept for religious believers whose assumptions about the world were shattered by it, but Darwin’s The Descent of Man, published 12 years later, posed even greater challenges to people who did accept it, and those challenges continue today. It has often been noted that a disorienting consequence of the Enlightenment was to force people to recognize that humans were not created at the center of the universe in the image of God, but instead on a remote dust-speck of a planet, in the image of mold, rats, dogs, and chimps. For the entirety of recorded history, moral beliefs about humans had been based on the idea that people were in some fundamental sense apart from the rest of nature. Darwin disabused us of that notion once and for all. The scientific and social upheaval that has occurred since Darwin has been an extended process of coming to terms with a unification of humans and the rest of the natural world.

On our 4.5-billion-year old planet, life is perhaps as much as 3.7 billion years old, with photosynthesis and multi-cellularity (appearing dozens of times independently) around 3 billion years old. Oxygen levels began to rise some 650 million years ago or even earlier (coinciding with the Metazoan stage); plants, animals, and fungi emerged on land perhaps 480 million years ago; forests appeared around 370 million years ago; and modern groups such as mammals, birds, reptiles, and land plants originated about 200 million years ago. The geological record shows that there have been five global mass extinction events, the first of them about 540 million years ago. The records also suggest that 99% of the species that have ever existed (perhaps 5 billion in number) have become extinct.

The stone is still there in the garden. That’s what gets me. It’s not the house itself – houses decay slowly and can be preserved pretty easily, especially in Britain where even an eighteenth-century country house is not “old.” It’s not even the tree behind the house, alive when Charles Darwin still lived in his Down House, now propped up by guywires against inevitable collapse as a kind of totem of the great naturalist’s existence. If you leave the rear exit, the one that takes you to Darwin’s preserved greenhouse and the stunning flora on a pretty path lined in that particular English way of making the perfectly manicured seem somehow “natural,” you might glance to the left and see behind a small iron fence a one-foot-wide stone. A round mill stone or pottery wheel, it was, or appears to have been.

Ever since living beings arose from non-living organic compounds on a primordial planet, more than 3.5 billion years ago, a multitude of organisms has unceasingly flourished by means of the reproduction of pre-existing organisms. Through reproduction, living beings generate other material systems that to some extent are of the same kind as themselves. The succession of generations through reproduction is an essential element of the continuity of life. Not surprisingly, the ability to reproduce is acknowledged as one of the most important properties to characterize living systems. But let’s step back and put reproduction in a wider context, the endurance of material systems.

Forensic DNA typing was developed to improve our ability to conclusively identify an individual and distinguish that person from all others. Current DNA profiling techniques yield incredibly rare types, but definitive identification of one and only one individual using a DNA profile remains impossible. This fact may surprise you, as there is a popular misconception that a DNA profile is unique to an individual, with the exception of identical twins. You may be the only person in the world with your DNA profile, but we cannot know this short of typing everyone. What we can do is calculate probabilities. The result of a DNA profile translates into the probability that a person selected at random will have that same profile. In most cases, this probability is astonishingly tiny. Unfortunately, this probability is easily misinterpreted, a situation we will see and discuss many times in the coming chapters.

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.

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.

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.

This chapter is about the public image of genes. But what exactly do we mean by “public”? Here, I use the word as a noun or an adjective vaguely, in order to refer to all ordinary people who are not experts in genetics. I thus contrast them with scientists who are experts in genetics – that is, who have mastered genetics-related knowledge and skills, who practice these as their main occupation, and who have valid genetics-related credentials, confirmed experience, and affirmation by their peers. I must note that both “experts” and “the public” are complex categories that depend on the context and that change over time. There is no single group of nonexperts that we can define as “the” public, as people around the world differ in their perceptions of science, depending on their cultural contexts. We had therefore better refer to “publics.” The differences among experts nowadays might be less significant than those among nonexperts, given today’s global scientific communities, but they do exist. Finally, both the categories of experts and publics have changed across time, depending, on the one hand, on the level of experts’ knowledge and understanding of the natural world, and, on the other hand, on publics’ attitudes toward that knowledge and understanding.

Stories of family deceits and deceptions have become commonplace in a media receptive to personal tales of triumph and tragedy. A distinguished geneticist learns in his mature years that his mother, while married to his legal father, had a secret affair that begat him. A best-selling author discovers that her paternal DNA was from a medical student serving as a sperm donor and not her legal father, who traced her ancestry deep into Eastern Europe. A woman who, as a newborn, was left in a bag abandoned in the foyer of a Brooklyn apartment building searches for her biological parents 23 years later. These revelations are the result of the millennial DNA ancestry revolution.

At the end of December 2019, an outbreak of pneumonia cases of unknown origin was reported in Wuhan, Hubei province, China. The patients presented with high fever and had difficulty breathing. Some, but not all, of these cases were in people who visited the Huanan Seafood Wholesale Market, where, in addition to seafood, a variety of live animals were also sold. Other infections occurred in people staying at a nearby hotel on December 23–27. All tests carried out by the Chinese Center for Disease Control and Prevention for known viruses and bacteria were negative, indicating the presence of a previously unreported agent. A new virus was isolated and its genome sequenced, revealing a similarity with SARS-like coronaviruses found in bats. Although very similar to the virus causing severe acute respiratory syndrome (SARS) in 2003, it was different enough to be considered a new human-infecting coronavirus. Clusters of infected families, together with transmission in medical settings, indicated that the virus had the ability to undergo human-to-human transmission. A month later, by the beginning of February 2020, the virus was found in several countries across the globe, and on March 11, 2020, the World Health Organization (WHO) declared it a global pandemic. The disease caused by the new coronavirus was called coronavirus disease 19, or COVID-19.

The authors will consider the reasons for writing papers, their mindset, and then are given an outline of the whole process involved from setting out to the final publishing of an article. This is an overview given a simply as possible to the whole task ahead of them.

The two great creative processes of biology are evolution and development. You and I, as adult human beings, are products of both. Evolution took about four billion years to make the first human from a unicellular organism that emerged from the primordial soup. Development, in the form of embryogenesis together with its post-embryonic counterpart, takes less than 20 years to produce an adult human from a different unicellular organism – a fertilized egg or zygote. By this measure, development operates more than 200 million times faster than evolution. However, despite their very different timescales, the two great creative processes of biology are intrinsically interwoven. Evo-devo is the scientific study of this interweaving. Its full name is evolutionary developmental biology, but because this is an unwieldy phrase it is almost universally referred to by its nickname.

Among biologists and philosophers of biology there is no general agreement on a definition of development. Development is not necessarily the history of the individual, or the sequence of changes from egg to adult (adultocentrism). The notion that the adult stage is the target of development is unacceptable, both because it implicitly gives development a purpose, and because it does not apply to the biology of many organisms. In the common use of the term adult, two different notions are confused: adult as reproductively mature stage and as a stage that maintains its morphological organization until the onset of senescence or death. However, reproductive maturity and the presence of definitive morphological condition are not always associated. The divide between developmental processes and mere metabolic changes is not always clear-cut. Modern developmental biology is not the same as the descriptive and experimental biology of the past. Partly owing to strong focus on genetic control and molecular-level processes, most research effort is restricted to a few model species; but these are not necessarily representative of developmental processes in more or less distant relatives.

Plants are essentially modular organisms; each individual plant consists of distinct but connected organs. In their turn, the organs are composed of cells, which are mostly grouped into tissues. Vegetative organs support photosynthesis and plant growth, and reproductive organs enable sexual reproduction. In seed plants, the primary vegetative organs are the root, stem and leaf (Figure 1.1). Roots and stems have well-defined growing points at their apices, but the leaves are determinate lateral organs that stop growing when they reach a particular size and shape. When a seed germinates, the seed coat (testa) is ruptured and the embryonic structures emerge from opposite poles of the embryo: a seedling root (radicle) grows downwards from the root apex and a seedling axis (hypocotyl) bears the first leaves (cotyledons) and the shoot apex, which ultimately develops new foliage leaves.

To many biologists, science and philosophy may appear an odd couple without much in common. Perhaps the word “philosophy” will even bring to mind endless arguments and speculation about whether the chicken or the egg came first, without ever getting anywhere. After all, are philosophers not still arguing over the same things as Aristotle and his fellow Greeks? Well, yes. But biologists too are concerned with the questions that occupied Aristotle: what living beings are and where they come from; how they develop, function, and interact with one another; and why there are so many forms and how those forms should be classified. There has been tremendous progress in biology, of course. But it does not appear that biologists will ever run out of questions. This is because good science does not only reveal new things about the world; it also reveals that there are things we did not even know we could know. So we want to know more.

Francis Bacon, one of the luminaries of modern science, is thought to have said that “knowledge is power.” Since Bacon made that statement, it has become abundantly clear that humans have a very distinct and difficult “knowledge problem.” There is a fundamental defect in how we come to know anything, and while this is recognized as a problem, the depths of the problem are seldom appreciated and even less frequently discussed. At first glance such a statement may seem ridiculous. What is the problem in saying someone knows something? I know where I am and what I’m doing. I know the names and faces of my friends, family, and acquaintances. I know how to drive a car, how to cook (at least somewhat), and how to pay bills. In fact, just to navigate the tasks of daily life one has to “know” a great number of things.