CONTENTS

Introduction: Why does science matter?

Chapter 1: Are humans the pinnacle of evolution?

Chapter 2: Why don’t we run cars on water?

Chapter 3: What makes a rainbow?

Chapter 4: How does a cat always land on its feet?

Chapter 5: Why is soil brown?

Chapter 6: Why don’t we go to Mars?

Chapter 7: Could we bring dinosaurs back to life?

Chapter 8: Could a supervolcano kill us all?

Chapter 9: Could we live for a thousand years?

Chapter 10: Why don’t satellites fall down?

Chapter 11: What would happen if you fell into a black hole?

Chapter 12: Why can’t you uncook an egg?

Chapter 13: Can we talk to the animals?

Chapter 14: What’s happening with the climate?

Chapter 15: Is this the end for antibiotics?

Chapter 16: Are stem cells the future of medicine?

Chapter 17: How does a caterpillar turn into a butterfly?

Chapter 18: What is the most economical way to drive a car?

Chapter 19: Why do we find seashell fossils on mountains?

Chapter 20: Can plants feel pain?

Chapter 21: Do we all see the same colours?

Chapter 22: Will we ever find a cure for cancer?

Chapter 23: Could intelligent machines take over?

Chapter 24: What’s the difference between a person and a lettuce?

Chapter 25: How will the universe end?

INTRODUCTION

Why does science matter?

The word ‘science’ comes from the Latin scientia, from scire, ‘to know’. Science in its true sense is not restricted to any set of subjects, but is all knowledge.

Knowing about science means knowing about the world around you – and even the world within you – and how it works. It is far more wide-ranging than the science we associate with the school curriculum.

A long history

Science is an endeavour that began at least as long ago as the Ancient Greeks, and in some forms in Mesopotamia 4,000 years ago. But it hasn’t all been plain sailing. In some parts of the world there have been long periods during which science was shunned or even forbidden. During these times people adopted different organizing principles, including the invocation of spiritual and mystical explanations for phenomena. Often the notion that only certain types of knowledge should be sought has stifled scientific inquiry.

Science is characterized by a particular way of organizing knowledge. This way developed in the 17th and 18th centuries, when people became interested in discovering the natural laws that govern the behaviour of the physical universe.

Ancient traditions: in this wall panel from 865–860BC, King Ashurnasirpal appears twice on either side of a Sacred Tree, possibly symbolizing life.

The scientific method

The scientific method that lies at the heart of modern science developed during the Enlightenment, a period of renewed interest and confidence in inquiry into the natural and physical world. The method is rooted in empiricism – that is, what can be objectively observed and tested, rather than approached only through reason.

An idea – a theory or hypothesis – emerges from observations of the world and from thoughts about why it might be as it is. Perhaps someone observed that plants grow better at the sunny end of a field than the shady end, and so proposed that sunlight helps plants to grow. The hypothesis could then be tested by experiment or structured observations, and the results examined dispassionately and objectively to determine whether or not they support the hypothesis. Most of us met this method in school science lessons with simple experiments. The hypothesis might have been that sugar dissolves more quickly in hot water than in cold water, or that a truck will run faster down a steep slope than a shallow one. But in a school science lesson, the teacher and the textbook (and often the pupil) already have the answer. In real-world science, the answer is not generally known. Some hypotheses are very tentative and proven to be wrong. Others look fairly obvious, but must still be tested before they can be treated as an accurate representation of fact.

A HYPOTHESIS MUST BE FALSIFIABLE

It may seem a strange way of looking at things, but whether or not a hypothesis is valid depends on whether it can be proved to be wrong. A hypothesis such as all dogs are more than 5cm tall can be proved wrong by finding a smaller dog, but it can’t be proved right – we would need to examine every dog that has ever lived or will ever live.

It’s perfectly possible to come to the wrong conclusion about the state of things just by looking at them. Before the invention of the microscope, around 1600, people reasonably assumed that the smallest living things were tiny bugs, such as fleas. We now know that most of the living things in the world are much smaller than this and can only be seen with the aid of a microscope, hence the term ‘microscopic’. The way we look at the world and the deductions we make about it have been changed by the invention of the microscope.

Why know about science?

Curiously, it became rather trendy in the late 20th century to claim to know nothing about science or mathematics. There was a popular belief that scientific knowledge was somehow at odds with being a cultured individual, when in fact it is central to it. In 1959, the English scientist and novelist C.P. Snow delivered a famous lecture in which he spoke of the distance and even animosity that existed between the ‘two cultures’ of science and the arts, or humanities. This deep division in intellectual life was, he felt, holding up human progress. The divide remained, and even increased, in the following decades. It might now be narrowing, but it’s far from closed.

More people, though, now recognize that knowing about science is not a mark of philistinism, but the very opposite. An informed appreciation of the world around us, the laws it follows and how we can discover those laws, puts us in the best position to make the most of our individual lives and the resources the planet affords us as a species. The loss of wild places was mourned poetically by 19th-century writers such as Wordsworth or Thoreau and demonstrated a need to find out how to renew and protect the environment. But this remorse for what humans have done to the world, invoked through the arts, can be harnessed in helpful action through the application of science and understanding.

‘So the great edifice of modern physics goes up, and the majority of the cleverest people in the western world have about as much insight into it as their Neolithic ancestors would have had.’

C.P. Snow

Be prepared

Understanding something of science enables us to make informed decisions and protects us from the deceptions practised by large corporations, the media and national governments against an uninformed public. A little knowledge can protect you from scare-mongering and scams as well as raise your engagement in and wonder at the world around you.

This book can’t hope to cover all the aspects of science that will equip you to understand what lies behind every news story or topical issue. But it can lead you to think more carefully about the stories you encounter and about the natural world. It can encourage an interrogative, curious or ‘scientific’ approach and a respect for the disciplined organization of knowledge that underpins the modern world.

CHAPTER 1

Are humans the pinnacle of evolution?

We like to think we’re at the top of the evolutionary tree – but are we? And is there even a tree to climb to the top of?

Ladder, chain or tree?

More than two thousand years ago, the Greek philosopher Aristotle wrote about the scala naturae, or ‘ladder of Nature.’ He ranked organisms (living things) in a hierarchical order, from the lowliest – simple plants – to the most advanced – human beings. This wasn’t based just on feeling superior to mushrooms or flatfish. He proposed that organisms have different types of souls according to their nature and needs. The soul, he claimed, gives the physical matter of the body its capabilities.

According to Aristotle, a plant has a soul capable only of growth and sustaining life, but an animal has a soul capable of growth, sustaining life, and moving around. A human is better still, as it can do all those and is also capable of reason. For the Ancient Greeks, the rational soul placed humans at the top of the ladder.

Aristotle distinguished within the broad categories of plant/ animal/human, too. He considered trees to be superior to smaller plants, and blooded animals (such as wolves) to be superior to bloodless animals(such as spiders). The blooded/ unblooded distinction coincides with the modern division of vertebrate/invertebrate (animals with or without a backbone).

In the 3rd century AD, the Egyptian-Roman philosopher Plotinus added a new rung at the top of the ladder for the gods to stand on. With the coming of Christianity, Ancient Greek theories were assimilated into Christian thinking where possible. The ladder of nature became the ‘Great Chain of Being’. The pagan gods were replaced at the top by different classes of angel and archangel, with the Christian God at the very top. Just as Aristotle’s model had organisms on distinct rungs, ascending from lowest to highest, so the chain had discrete links. And although a chain could lie in a tangled heap on the floor, this one didn’t. It was extended vertically, with angels at the top and the lowest organisms – algae, perhaps – at the bottom.

Far more organisms were known in the Middle Ages than had been familiar to Aristotle, and more were constantly being discovered over the following centuries as European adventurers, explorers and conquerors travelled further afield. The Americas, Asia, the Pacific Islands and Australasia all yielded new beings that had to be fitted into the chain, and they were. The prevalent belief was that Creation was full – God had created a perfect world, with an organism to occupy every niche, leaving no gap unfilled, even if people had not yet found all the organisms.

In a chain, everything is linked. Instead of taking a step up from plants to animals, as on a ladder, the chain model proposed intermediate links. These could be represented by organisms that were thought to share aspects of both – so shellfish or sponges that don’t move are on the border between plants and animals. But some odd hybrids were also described, such as barnacle geese, which were thought to grow on trees.

No change

Both models of a ladder and of a chain describe a static order. The Abrahamic religions make the fixity of nature explicit. The account of Creation given in Genesis is of God creating the plants, then the animals and, finally, humans. The other organisms were created purely to serve humankind, so humankind is clearly their superior. Just as important as humans’ superiority is the idea that all organisms have existed from the start. Creation was both perfect and complete: the world did not change and had not ever changed. How could it change, if God had created a perfect world?

The discovery of fossils challenged that notion. The fossils of sea creatures were found far inland, even on hills and mountains. And then, starting in earnest at the beginning of the 19th century, people began to uncover fossils of animals very unlike those that were alive at the time. First the fossil remains of plesiosaurs and ichthyosaurs were discovered, then Iguanodon and Hadrosaurus followed. The conclusion that large, unfamiliar animals had once walked (and swum) the Earth became irresistible for many scientists, though others clung to the Creation narrative and tried to explain away the discoveries. In the second half of the 19th century and the first years of the 20th, the great dinosaurs were discovered – Apatosaurus, Tyrannosaurus, Stegosaurus, Triceratops – and the human view of the past changed forever.

BARNACLE GEESE – HATCHED FROM BARNACLES, GROWN ON TREES

How could a society with no notion of migratory birds account for the fact that they never saw barnacle goslings or saw the parents sitting on a nest? They concluded that the geese hatched from barnacles. Barnacles are often found on timber in the sea. Clearly the wood had fallen into the sea with the goose-pods growing. Perhaps they were produced from the sap in the wood. The barnacles hung down from timbers in their hundreds and – when no one was looking – grew to maturity and the geese flew away or dropped into the sea to swim off. Now we know that barnacle goslings hatch from eggs, like any other bird.

Evolution evolving

The theory of evolution did not spring fully formed from nowhere (or from Darwin’s brain) in the mid-19th century. Even before Aristotle, some of the Greeks had proto-evolutionary ideas.

Anaximander (c.611–547BC) proposed that the first animals were formed from bubbling mud. They had lived in the water at first, but as the land and water separated over time, some of them adapted to living on land. He believed that even humans had developed from earlier, fish-like animals. After a promising start, though, western thought became bogged down in the no-change theory of Creation. Evolutionary ideas did not re-emerge in the West for around 2,000 years.

From the 18th century, evidence that organisms do change was piling up. Greater interest in taxonomy, especially after the work of the Swedish naturalist Carl Linnaeus (1707–78), showed there were clear similarities between some species widely separated by geography. Camels and llamas are similar, as are jaguars and leopards, yet there is an ocean between their territories. Scientists attempted to explain these puzzles first within the framework of traditional Christian thinking. Perhaps organisms had started off perfect but degenerated over time. Or, if they all started out in the far north and moved southwards, that would explain how animals in the New World and Old World could resemble one another – both the llama and the camel could have degenerated as they travelled through time and terrain. Genesis made allowance for degeneration, in a way, since the Fall of