Fifteen years ago, I was asked to give a lecture in honour of the memory of William Harvey. The lecture took place on the anniversary of his death in June 1657, 350 years previously. I expect you will know why he continued to be remembered and celebrated for so long – his discovery of the circulation of the blood. The lecturer was expected to reflect on his life and scientific contributions and then to speak of something more up-to-date, and I decided to discuss climate change, a phenomenon that was then subject to some scepticism. I tried to put myself into Harvey's mind as he lay ill, anticipating death. Here is how I started:
He was close to 80 years old and must have looked back on his life with a mixture of satisfaction and sorrow. He perhaps reflected on his achievements in describing the circulation of the blood and the development of the embryo, achievements so well known that he was in his lifetime characterised as 'the immortal Dr Harvey'. He had also achieved extraordinary recognition as a physician, being personal doctor to King Charles I (who, it has to be said, was justifiably wary of the ministrations of physicians). He was an establishment figure, a doughty defender of the exclusive rights of the London College of Physicians to determine who could and could not practise physic. But he must also have thought of his disappointments; the loss of his wife, his hardships during the Civil War including loss of his house and his book on insects, and the execution of his friend and sovereign, King Charles I, eight years earlier.
England's experiment with republicanism was failing. Cromwell was old and dying, and his succession was unclear. London was becoming anarchic, and religious sects including Quakers and Anabaptists were spreading discord and riots. A further three years were to pass before the Restoration of the monarchy and the return of Charles II. It may reasonably be speculated that Harvey welcomed the release from the pain of his chronic gout and the misery of the times around him. But the immortality of his work was assured; he had lit a candle that still burns brightly to this day.
The candle was experimental science, a pursuit taken up enthusiastically by philosophers in London including Robert Boyle, John Evelyn and Christopher Wren, who grouped together under King Charles II's sponsorship to form the Royal Society of London. Boyle's experiments showed that animals require something in the air to survive. The candle brought enlightenment to Scotland, where in the 18th century Joseph Black discovered carbon dioxide, the first known gas, and his pupil Daniel Rutherford discovered nitrogen, to the north of England where the radical Yorkshireman Joseph Priestley discovered oxygen, and to Paris where Lavoisier showed how animals use oxygen and produce carbon dioxide. Priestley also showed the opposite, that plants use carbon dioxide and give off oxygen. By the late 18th century we knew the carbon cycle, the cycle of life. And by then the Industrial Revolution, based on exploitation of labour and coal had begun.
The birth of modern chemistry, understanding of atoms and their combination into molecules, came from the work of John Dalton in Manchester, first announced in 1903. Organic chemistry, which deals with carbon-containing molecules and their interactions, developed from experiments on tar derived from coal, the fuel of the Industrial Revolution, and from organic chemistry came biochemistry, the study of the molecules of life, plants, animals and microbes. As medical students, we strived to learn how molecules derived from our food were broken down and reconstituted in complex cycling reactions to provide our cells with energy.
Just as the economy of life on this planet depends on the cycling of chemicals such as carbon and nitrogen, so each living cell in every organism derives its energy from a cyclical reaction of simple molecules. We humans and other animals use energy ultimately derived from the sun's radiation, passed through the plants and other animals we eat, to make the carbohydrates, proteins and fats of our bodies, molecules in which the chemical bonds conserve that energy. We release the energy by breaking those bonds and consuming oxygen, allowing our cells to grow and divide. As animals, our exhaust from this energy consumption is mainly carbon dioxide and we survive because this is balanced by our ancestors, the plants, which use that gas in reverse processes driven by sunlight to produce oxygen.
Ultimately, whether plant, animal or microbe, we die – our tissues are consumed by microbes or by fire and the chemical bonds within their molecules are put to use by other organisms. The cycle of life continues and if we have had children some of it remains in them. But we cannot, must not, assume that our species, the human race and its organisation that we call civilisation will continue indefinitely. We are breaking the most fundamental cycle that sustains animal life on Earth, and the Earth, Gaia, is responding in the only way it can. It is heating up until we are forced to stop polluting our air with greenhouse gases.
Things looked pretty bad to Harvey as he lay dying, but the ingenuity of mankind flourished when Charles II was restored to his Scottish throne and crowned King of the United Kingdom in 1660. The growth of science from that period is what taught us to understand how the world and life work and our small place in the circular chemistry of the universe. We know some of the immutable laws of nature and we know that we challenge them at our risk – the risk of breakdown of civilisation, perhaps leading to the fall of mankind as the Earth's dominant species.
It will not have escaped your notice that last week the coronation of another monarch, another Charles, took place; the crown encircled his head. I recall the spirit of optimism that attended the coronation of his mother and I hope that last week’s ceremonies engender a similar rise in our spirits. But it is difficult to avoid thinking also of the words that Shakespeare put into Richard III's mouth: 'For within the hollow crown that rounds the mortal temples of a king, keeps death his court. And there the antic sits...'.
King Charles III saw that antic long ago, at a time when his views on the environment attracted much cynicism and even ridicule, but he was right – the future of mankind and of the civilisation that supports monarchy depends on us individually and collectively living in harmony with nature. Despite his wealth and the obligations placed on royalty, he has made serious efforts to promote a sustainable lifestyle and good agricultural practice. The reign of Charles II saw the birth of modern science and gave us the tools to understand how to live sustainably. Now more than ever in human history we require science to help us avoid the disaster that abuse of our technologies and ignorance of the harm that inefficiency and waste has caused to our environment.
All life, plant, animal and microbial, depends on circles, recycling food, air and the sun's energy. Whether we survive as an organised species or collapse into warfare and famine depends on how circular our individual and collective economies become. Charles II reigned for 25 years. Should Charles III have the longevity of his mother, he may live long enough to see which way we choose to go, because the answer will be apparent within that short timescale. If we, you and I, are not trying to live a sustainable, circular lifestyle already, we are choosing collapse. As the crown encircled Charles III's head, I was thinking of this. I hope you will join me.
Anthony Seaton is Emeritus Professor of Environmental and Occupational Medicine at Aberdeen University and Senior Consultant to the Edinburgh Institute of Occupational Medicine. The views expressed are his own