The Book of Humans A Brief History of Culture, Sex, War and the Evolution of Us

Historically, humans have long considered themselves special compared to the natural world around them. It shows, for example, in old depictions where humans are at or near the top of a chain of lifeforms, with only angels and gods above us. Darwin caused a tremendous ruckus by saying we were descended from primates, and evolutionary biology has since had a long history of diminishing our anthropocentric worldview. With The Book of Humans, self-professed science geek Adam Rutherford has written an entertaining exploration of human evolution, showing that, amidst the teeming multitudes of lifeforms surrounding us, we are really not that special. And yet we are.

Rutherford takes a two-pronged approach in this book, first looking at tools and sex in both humans and animals, showing that we are not unique, then looking at what it was in human evolution that drove us to become who we are today and why we are special.

Archaeologists have uncovered a rich record of tools that have formed the basis for naming historical periods – hence we used to talk of the Stone Age, Bronze Age, and Iron Age (archaeologists have since moved on from this three-age system, though it remains firmly lodged in the public imagination). But we are not the only species to use tools and textbooks have been written about this (see e.g. Animal Tool Behavior or Tool Use in Animals). Many of the examples Rutherford mentions here have been widely reported by the popular press. Who, by now, has not heard of sea otters and monkeys using rocks to crack hard food items, of chimpanzees and New Caledonian crows fashioning branches into sticks to retrieve insects or other tools, or of dolphins using corals on their beaks to forage for spiky food items hiding in sediment?

But it gets better. Fire, long thought to be a tool unique to humans (see Fire: The Spark that Ignited Human Evolution or Catching Fire), is not our sole dominion. Some primates specifically forage in recently burned areas and some Australian raptors will even pick up smouldering sticks to actively spread wildfires. And though it might be an anthropomorphic bridge too far to say that other animals wage war, we have certainly observed group violence and war-like behaviour in animals. Farming and fashion are similarly not unique to us.

And then there is sex. We love it, and clearly, it serves far more than just a reproductive purpose. But the same is true for animals. There has been a flurry of slightly raunchy but ever so amusing books giving us the proverbial ins and outs of sex all around us (e.g. Sex on Earth, Nature's Nether Regions, The Nature of Sex, or The Dawn of the Deed). Whether it is masturbation, oral sex, homosexuality, or even necrophilia – Rutherford shows that the animal kingdom seethes with sexual activities that clearly do not serve reproduction. Yet, he is careful and conscientious here. Do animals do this because it is fun? Possibly, but until we find a way of asking them, we have to be careful not to anthropomorphise. Similarly, he is wary of calling sexual violence observed in animals (e.g. dolphins) rapeor of attempts at explaining rape in humans in evolutionary terms (see e.g. A Natural History of Rape). Rutherford strongly argues that the temptation of evolutionary just-so stories trivialises a criminal act.

So, on several fronts, we are really not all that special. Yet, to any observer, humans have achieved things not seen anywhere else in the animal kingdom. And in the second part of his book, Rutherford explores this matter. He delves into the genetic differences that set us apart from our relatives. Although he is again quick to ground the reader and steer them away from simplistic explanations of “a gene for X”, there have been some key genetic changes that have occurred that contribute to brain development and speech. He reviews the wonderful work on ancient DNA and what it reveals about our closest relatives (see also my review of Who We Are and How We Got Here). There is our advanced cognitive development (theory of mind, complex emotions such as regret, or mental time-travel). And then there are the tools, musical instruments, carved objects, and cave paintings that we have found. But even here, recent research shows that we are not unique and Neanderthals shared this with us (see The Neanderthals Rediscovered and the upcoming The Smart Neanderthal for more).

Brimming with findings from recent research, Rutherford conscientiously steers clear of anthropomorphism and sensational claims, pointing out where the limits of our knowledge are and openly marking the areas where we just do not know the answers. He ultimately refrains from pointing at any one thing to say: “here, this, this switch or trait or development is what makes us uniquely human”. Instead, this book revels in the messy reality that is biology and skillfully navigates the reader through the many traits and developments that, collectively, have made us who we are. Wonderfully crafted, this is a readable, fun exploration of human evolution and how we compare to the animals surrounding us that is recommended if you enjoyed a book like The Creative Spark.