I was both excited and nervous to see Professor Alice Roberts on tour with her new book Tamed: 10 Species That Changed Our World in the sort of way you only ever are if you’re about to meet a bit of a personal hero and would really-rather-they-lived-up-to-your-expectations-if-it’s-all-the-same-to-everyone-else? I needn’t have worried. Roberts began with the sort of easy confidence that comes from lots of practice of talking to people about something you know an awful lot about, putting everyone at ease before wrapping us up into a world of plants and animals that was both familiar and wholly unknown.
Her book, the subject of the talk, considers the interactions humans have had with the wild world and how we began to shape it, whether knowingly or entirely by accident, to suit our needs, to work for us, and ultimately to allow us to become the incredibly successful species that we are now. Hundreds of thousands of years of our ancestral history were spent in the pursuit of wild species for food and fuel and countless other uses, and then an environmental revolution occurred. Across years and miles, from the smallest of beginnings, but ultimately with global consequences, the way that we lived alongside other species began to change.
The talk and the book both take in all the usual suspects you might consider when asked to think about ‘tame’ species: dogs and cattle and horses (not cats though, those guys are more accurately described as semi-domesticated – as any cat owner can attest). It also included some more unexpected species: rice, wheat, maize, even apples. But what really struck me was the ease with which Roberts wove between theories and academic disciplines, drawing a fact from here, a finding from there, to show a bigger picture which would not have been possible without an interdisciplinary understanding of the world. The most striking example of this was in her explanation of the first dogs.
Dogs share 99.5% of their genetic information with wolves and, more specifically, with one species of wolf – the European Grey. Incredibly, this means that all the genetic variation we see within our domesticated dogs today comes from 0.5% of their genome. But for how long have they been our companions? It was a long established hypothesis in archaeological circles that dogs were first domesticated around 15,000 years ago, at the end of the last Ice Age. There is plenty of archaeological evidence of domestic dogs from around 14,000 years ago (which is in itself an amazing idea, especially as we consider that the first stirrings of agriculture can only be traced back to 12,000 years ago at the earliest). However, in 2005 a group of geneticists published a study of mitochondrial DNA (which we all receive, humans and dogs alike, passed down to us wholesale from our mothers) to create something of a ‘family tree’ of domesticated dogs and their wild wolf cousins. Their findings were that the domestication of dogs may have occurred at one of two possible points: around 15,000 years ago or, potentially, around 40,000 years ago. This, incredibly, would be well before the climax of the last Ice Age around 20,000 years ago.
To try and test the claims of the geneticists, some archaeologists went back to ancient wolf skulls found in archaeological sites across the world to see if they could find any ‘dog-like’ characteristics. They tested a small sample of 9 skulls and while 5 proved most likely to be wolves and one was inconclusive, a further three might have been misidentified when they were first discovered – that is, they might have been dogs. Astonishingly, the oldest of these dated to around 36,000 years ago. Not long after this discovery, another skull, dating from around 33,000 years ago was also re-categorised as more dog-like. Increasingly, it was looking like the far older date of domestication – about 40,000 years ago – might be the correct one.
Offering a somewhat frustrating twist to the story, it was at this point that another team of geneticists came forward to say that, according to their own research, it seemed likely that dogs actually were domesticated much later, somewhere between 11,000 and 16,000 years ago. Those two dog-like skulls identified by the archaeologists might have been domesticated dogs that were ‘dead ends’, without ancestors that survived to the present day, or they might have been other unknown species. They might just have been weird wolves.
But hope was not entirely lost for the very old dog. The later date of domestication was dependent upon a number of assumptions by the geneticists about the rate of mutation in the mitochondrial DNA and the generation times between mothers and pups. This information was inferred from present-day knowledge of dogs and wolves. In order to accurately check this rate of mutation, ancient DNA was needed to act as a starting point from which the geneticists could work forward to the present day. This opportunity presented itself in a paper published in June 2015. A transatlantic team had sequenced a section of mitochondrial DNA from a wolf bone known to be 35,000 years old. Using the information gathered from this ancient bone, the geneticists were able to work out that the assumed rates of genetic mutation, and the length of generations they were using, were in fact much too fast (they would have dated the ancient wolf bone at around 10,000 to 14,000 years old – less than half its actual age). With this in mind, a new slower rate was produced. This rate predicted the divergence of dogs and wolves to be around 27,000 to 40,000 years ago, much more in line with those ancient skulls. The combination of these studies, theories and experiments, has culminated in a complete transformation of the way we understand the domestication of dogs. Dogs, it seems, have been at our sides for far, far longer than we thought.
This vastly simplified version of Roberts’ rendition goes some way to showing how adept she is at weaving together information taken from a broad range of sources to explain complicated ideas simply and meaningfully. It is also a champion for an interdisciplinary approach to our knowledge formation. Roberts spoke engagingly, with warmth and humour, about complicated topics in such a way that everyone was enthralled, no matter their prior knowledge or personal interests. She spoke to the importance of archaeological, historical and genetic understanding and the power of drawing them together to learn something new. Rather unsurprisingly, she’s still my hero.