Some people are rather dismissive of the impact that we are having on our environment as our civilization feels secure. We are not the first people to think like this. In his excellent book The Earth Transformed: An Untold History, Peter Frankopan catalogues correlations between past changes in the climate and other aspects of the environment on the rise and falls of civilizations past. It doesn’t take much to shatter illusions of stability. When supply chains required to maintain large populations break down, individuals struggle to survive and the key structures that are so central to existence disintegrate. When ancient civilizations have collapsed, they have done so quickly, and often with great loss of life. Many ancient and long-lived civilizations collapsed, with few signs of them remaining today. If history teaches us any lesson, it is to be thankful for periods of environmental stability, as these have been good for humanity. We change our climate and the functioning of global ecosystems at our peril.
The people who lived in the first cities were anatomically the same as us and had the same intellectual capacity. The history of human civilizations is fascinating, and science has played a key role in piecing this history together by being able to non-invasively scan ancient archaeological sites and artefacts, and to use tools such as radiocarbon dating to estimate the age of objects. Yet the stories of these civilizations and the people that lived in them, although fascinating, are not central to an understanding of our existence. Different civilizations uncovered different truths of our universe as new technology was produced, largely by trial and error. The Greek and Roman empires may not have had to happen for you and me to exist, even if they did demonstrate new ways for societies to organize themselves. Civilizations have come and gone, with the key thing about humans being that we are capable of building them. The invention of science needed civilizations, and without them we could not have pieced together so much of the narrative of our existence. Details of the rise and fall of human civilizations have been told many times before and are beyond the focus of this book so they only get a brief mention.
Civilizations that have collapsed include the Mycenaeans, the Hittites, the Western Roman Empire, the Mayans, the Mauryan and Gupta civilizations of India, the Angkor of Cambodia, and the Han and Tang dynasties of China. These collapses were often triggered by climate change and resource shortages that resulted in civil unrest and war, and appear to have often taken most inhabitants by surprise. Societies, and complex organizations within them, are fragile. A combination of an overly authoritarian leader with a natural catastrophe can lead to the collapse of empires. Similarly, on occasion, more empathetic leaders have united people, enabling them to survive periods of hardship. Why do leaders differ in their approach to leading? What is it that causes individuals to be different? That is the focus of the next chapter. Why are we the way we are?
You and Me
I have so far told the narrative of how the universe, the Milky Way, our Solar System and the Earth came into being. I have explored physics, chemistry and biology, the emergence and spread of life, the evolution of consciousness and the rise of humanity. I have covered 13.77 billion years of the past, and we are nearing the present day and the end of this extraordinary journey. Then I can answer the question I posed at its beginning: were we inevitable at the birth of the universe, or are you and I just incredibly lucky? As the history has unfolded, things have become ever more localized as we have moved from the history of the entire universe to the rise of the first civilizations in a small corner of our planet. The last step is more local still, and it involves exploring why you and I are as we are.
I face two challenges in navigating this part of the journey. First, I do not know you. One reason I have described a little about my history is so you have an idea about the sort of person I am. I focus on me because I cannot answer questions as to why you might be short or tall, optimistic or pessimistic, shy or outgoing, why you might be scared to snorkel but happy to jump out of a plane, or why you might have remained single or are on your fifth marriage. Second, it is challenging to identify the cause of particular characteristics within one person. At the level of the individual, science can struggle to explain why you are anxious or relaxed. Answering questions about individuals requires understanding the detailed genetic and developmental mechanisms that have made you an introvert or an extrovert, shy or bombastic, and currently we do not fully understand these mechanisms. Nonetheless, scientists have made progress. They know that our genes, our experiences and chance all contribute to our characters, and the focus of this chapter is on these three processes.
Because I do not know you, I have put myself and occasionally my wife Sonya under the spotlight throughout this book. Before I dive into the topic of this chapter, I will briefly summarize key aspects of my journey. My childhood was happy with supportive parents, but I didn’t enjoy school much. Despite this, there was much to read and satisfy my curiosity at home, which meant I did a lot of learning outside school. A spell in Africa as a young man changed the course of my life and inspired a desire to understand why I exist. Because I had little idea of what to do for a living, I did a Ph.D., and followed an academic career trajectory; I still study the ecology and evolution of animals. The job involves publishing academic papers, although between 2017 and 2024 I took on leadership roles with the University of Oxford, which means I have sacrificed my research to focus on building a legacy for current and future biologists at Oxford. Sonya, my children and Woofler are very dear to me and are a constant source of happiness. This is my first book, and I wrote it without much of a plan on what to do once the first draft was finished, but I found a wonderful agent and publisher, and that is why you are reading it now. The reason I have told this personal story will now hopefully start to become clear: I want you to know some of these details to illustrate how experience, genes and chance can influence us all.
Lots of measurements can be taken from individuals such as adult height, birth weight, how extrovert we are, anxiety levels, sprinting speed at age twenty and intelligence. Your birthweight might be six pounds five ounces, and your sprinting speed at age twenty might be 15.6 mph, and these are called phenotypic trait values.
Values of any phenotypic trait vary across individuals within a population. You were probably a faster runner than I was at age twenty, but you are likely to be shorter than I am. I can say this with confidence because I am below average in running ability, but I am taller than the global average height. I am five foot eleven, while the global average for men is somewhere between five foot seven and five foot nine.