In 2017, scientists in Australia observed some striking avian behaviour. A handful of kites and falcons in the outback were seen picking up burning sticks from bush fires. The birds would then carry these smoking embers in their beaks to areas of dry grass and drop them. New fires were set off, triggering frenzied evacuations by small animals – which were promptly snatched from above by the waiting raptors.
Such actions are extraordinary, says Adam Rutherford, a science writer and broadcaster. “It is, as far as I am aware, the only documented account of deliberate fire-starting by an animal other than a human. These birds are using fire as a tool.”
Indigenous Australians occasionally deliberately start fires in order to flush out game, he notes. Did they learn the habit from birds? “Or maybe it is just a good trick and only us and the raptors have worked it out.”
Either way, it is clear humans are not the only ones who see fire as a means for getting what they want – and that is key to Rutherford’s examination of what it means to be human. In what way, exactly, are we exceptional as a species? Science has continually chipped away at the notion of human specialness, the idea of our being “the paragon of animals”. Prowess at pyrotechnics is just the latest “human-only” attribute that has since been revealed to have animal exponents.
So what is left? What behaviours uniquely define our species? The usual list includes speech, tool-making, culture, as well as art and fashion. We are masters and mistresses of all, but none are exclusive human attributes. Crows make and use tools; apes can be taught sign language; dolphins and birds have been observed adopting habits through cultural transmission; chimps have been seen using styles of headwear “just to be in with the in-crowd”, as Rutherford puts it.
That leaves war and sex, both popular human pastimes. But is either peculiar to our species? Sex certainly occupies a titanic amount of our time and interest. One study has indicated that in Britain alone roughly 900,000,000 acts of heterosexual intercourse take place every year. (That’s about 100,000 an hour, if you are interested.) Yet only 0.1% of these bouts of British bonking results in a conception – and that is a very, very low rate of reproduction. Our species has almost, but not quite, decoupled sexual intercourse from its replication, it seems.
But that still does not make us unique. Bonobo apes turn out to be even more genitally obsessed and sexually motivated than humans. All have intercourse several times a day, usually with different partners.
That leaves us with war. Again we seem infatuated with violence. Across the globe, armies are in states of constant preparation to undertake premeditated, armed conflict. We are a homicidal species. But once again we can see animal parallels – particularly, with the chimpanzee. Several observers, including Jane Goodall, have witnessed – over prolonged periods – bands of chimps that raid, slaughter and eventually annex the territories of rival bands of their species. Like humans, Pan troglodytes can be lethally aggressive.
In the end, Rutherford nearly runs out of candidates before plumping, somewhat desperately, for one last remaining attribute that he believes defines humanity: our intense social bonding and our desire to share ideas. This is the critical factor that separates Homo sapiens most conclusively from the rest of the animal kingdom, he argues. “Where we stand apart most significantly is in cultural accumulation and transmission. Many animals learn. Only humans teach.”
It is an interesting but scarcely revolutionary conclusion, though this should not detract from a book that is deftly outlined, concisely constructed and filled with intriguing observations and anecdotes. Rutherford is an engaging, witty writer. He is also a concise one. After several vast but worthy tomes about human nature that have been published recently, that makes this pithy homage to our species all the more welcome. An entertaining and blessedly succinct read.
• The Book of Humans: The Story of How We Became Us by Adam Rutherford is published by Weidenfeld & Nicolson (£18.99). To order a copy for £16.33 go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99
