Tamed
Page 2
There were five tents in the camp: tall and conical, like robust tipis. Each was built on a skeleton of seven or eight larch poles, covered with hides, all stitched together and tied in place against the wind. Under the snow, a ring of stones held the skirt of the tent down. The fallen snow, at least half a metre deep around the sides of the tipi, also helped to keep the hides secure. Between the tipis, the snow was trampled. The remains of a hearth lay in the centre. It was barely used now – during these frozen weeks, it was much better to light fires inside the tents. And so, in each one, a fire blazed in a central hearth. The contrast in temperature was extreme. As the families retreated into their tipis for the night, fur coats and trousers and boots were discarded in a great pile by the door.
Outside the ring of tipis was a place for chopping wood. One or two men would split felled larch trees all day, enough to keep the fires in the tents burning. In another place lay the scant remains of what had been a reindeer. It had been butchered into pieces, and there was little left apart from a few ribs and blood-stained snow. The hunters had killed it that morning, and brought it back to the camp. When they arrived, they had immediately opened up its belly to take slices of still-warm liver to eat, and to drink its blood. The rest was divided up amongst the five families, and carried off into the tents. Apart from the head – once the tongue and cheeks had been removed, the antlered skull had been carried back into the edge of the forest. A young man had taken it, tying it to his belt and climbing several metres up a larch tree before wedging the skull between a branch and the trunk: a sky burial; an offering to the spirits of the forest and the spirit of the reindeer itself.
After another meal of mainly meat, the families started to settle down for the night. Children were tucked up under piles of reindeer skins. The last adult to go to sleep in each tent stacked logs onto the fire. It would burn on for another hour or two. Then the temperature inside the tent would drop, almost to the ambient chill outside. But the reindeer fur would keep them warm, just as it had kept its original owners warm through the icy winters in this cold, northern land.
As the skeins of blue smoke escaping from the tops of the tents grew thinner, and the murmur of conversation died down, that meagre carcass on the edge of the camp drew scavengers out of the forest. Emerging from the taiga – like shadows, skulking and silent – the wolves approached the camp. They made short work of the remains of the deer, and then they prowled around the tents and the central hearth, searching for other scraps, before disappearing back into the trees.
The hunters were used to the proximity of wolves. They even saw a spiritual link with these animals, who were also eking out an existence in these sparse forests on the edge of the true tundra. But this winter, the wolves were more of a constant presence than ever before. They were in the camp every night. In previous years, they had occasionally come near during the hours of daylight – never within the circle of tipis, but close enough. Perhaps they were driven by hunger. Perhaps these wolves had been becoming bolder over years, even generations. Mostly, the humans tolerated them. But stones, bones and sticks were thrown at the wolves if they came too near.
It was at the end of that long, hard winter – surely longer and harder even than the one before – that one wolf, a youngster, came right into the centre of the camp. A girl of about seven was sitting on a log, mending her arrows, and the wolf came very close to her. The girl stopped what she was doing. She laid down the arrows, rested her hands on her knees and looked down at the trodden, compacted snow. The wolf padded a few steps closer. The girl glanced up and down again. Then the wolf came right up to her. She felt the wolf’s warm breath on her skin. Then the wolf licked her hand and momentarily sat back on its haunches. The girl looked up and into the blue eyes of the young wolf. An astonishing moment of connection. And then the wolf leapt up, spun round and bounded away, back into the taiga, back into the shadows.
The wolves seemed to be tracking the people that summer, as they in turn tracked the huge herd of reindeer, migrating in stages across the landscape. The snow melted and gave way to vast expanses of grassland. The reindeer would graze and move on. The people were always just one step behind, striking their camp each time the herd began to shift, setting up again when they were settled. Usually, the wolves would melt away in summertime, as hunting became more profitable than scavenging from human hunters. But these wolves – or at least some of them – had somehow found themselves drawn to the side of the humans, even joining in with the hunts – and profiting from the fallen prey.
It was a nervous, fragile alliance. The wolves were wary of the humans, and the humans of the wolves. There were stories of these predators snatching babies from camps, although no one seemed to have experienced this first-hand. There were tales of hunters bringing down a deer, only for wolves to claim the carcass, driving the human hunters away. The older members of the tribe were suspicious and cautious. But there was no doubt that the wolves had improved the success of the hunts. They could help to separate a reindeer or a horse from the herd, sometimes even bringing the animal down before the hunters got near enough to throw their spears. The wolves would flush out smaller game, too. The hunters rarely came home empty-handed. And so there was less hunger – especially during the tough winter months. More wolves ventured into the camp during daylight, and they didn’t seem aggressive. After a few more winters and summers, parents would even let their children play with the friendly wolf pups, tumbling and play-fighting in the space between the tents. Some wolves started sleeping close to the camp. It was clear that this pack had affiliated itself with the humans. When the tents were dismantled and wrapped up and the people moved on, the wolves moved with them.
Who domesticated whom? Had the wolves chosen the people or the people chosen the wolves? However it began, this alliance would change the fortunes of the humans and it would change the form and behaviour of their canine companions. After just a few generations, the friendliest wolves had started to wag their tails. They were becoming dogs.
This is clearly fiction. But it is fiction based on scientific facts that we can now be very sure of. Our modern dogs, in all their wonderful variety, are the descendants of wolves. Not foxes, jackals, coyotes or even wild dogs. Wolves. European grey wolves, to be precise. Our modern dogs share over 99.5 per cent of their genetic sequences with these grey wolves.
What drew wolves to our side? Archaeologists in the past have suggested that it could have started with the advent of farming. The lure of livestock – easy pickings for opportunistic predators – would have been hard to resist. But the earliest evidence of farming – marking the beginning of a new age for humans, the Neolithic – goes back some 12,000 years to the Middle East. Dog skeletons have been found at archaeological sites much older than this. Of all the animals and plants that have been changed by coming into close contact with humans, forming alliances with us, the dog seems to be our most ancient ally: the first people to have dogs were not farmers, but Ice Age hunter-gatherers. But just how far back into our prehistoric past can we trace that alliance? And where, how and why did it happen?
Deep in the icy past
The traditional story of the domestication of dogs saw this process taking place around 15,000 years ago, at the tail-end of the last Ice Age. This was the time when the ice sheets were retreating northwards, when trees and shrubs, humans and other animals began to colonise the higher latitudes of Europe and Asia once again. The tundra greened, rivers ran full and the sea level rose, as warmth and life returned to the icy north. The ice sheets that had gripped North America from coast to coast also began to retreat, and groups of humans migrated from the vast, continent-like Beringia into the New World.
There’s plenty of definitive evidence of domestic dogs from 14,000 years ago onwards: bones which are clearly those of dogs, not wolves, turn up in archaeological sites across Europe, Asia and North America. Yet there’s a possibility that these are relatively late examples. At the beginning of the twenty-first centu
ry, as geneticists started to team up with archaeologists to probe questions about the origin of domesticated species, a suggestion emerged: that the domestication of dogs could have begun much earlier, even tens of thousands of years earlier, than previously thought.
Geneticists began to approach the question of dog origins by looking at patterns of differences in dog mitochondrial DNA to reconstruct a ‘family tree’ for this small package of genes. The results could be interpreted in different ways – the reconstructed family tree was compatible with two, completely distinct models of dog origins. One suggested that dogs arose from multiple origins, around 15,000 years ago. The other fitted with an early, single origin of most dogs – going back 40,000 years. The discrepancy in timing between the models is large – the possible dates are not only separated by thousands of years, but by the peak of the last Ice Age, which climaxed some 20,000 years ago.
Mitochondrial DNA is just one strand, and actually just a tiny part, of the genetic legacy carried inside the cells of an organism. There’s much more information to be found in the chromosomes – the packages of DNA contained in the cell’s nucleus. There are thirty-seven genes in the mitochondrial genome, compared with some 20,000 in the nuclear genomes (of both dogs and humans). When geneticists moved on to the nuclear DNA of dogs, an earlier date started to look most likely. The first draft genome – the genetic sequence contained in all of the chromosomes – of the domestic dog was published in a paper in Nature in 2005. The domestic dog was clearly most closely related to the European grey wolf. The authors (of whom there were – incredibly – over two hundred) had not only worked on a thorough sequence of the dog genome, but had made a start on mapping variation amongst different breeds of dog, looking at where single letters in the DNA sequence varied – at more than 2.5 million positions in the genome. The analysis revealed genetic bottlenecks linked to individual breeds – in other words, the dogs’ DNA showed how each breed had started off with a handful of individuals, taking in just a fraction of the genetic variation that had existed across the species as a whole. Each breed represented just a small sample of that variation. Those bottlenecks, linked to the origin of different dog breeds, are really quite recent, probably happening around thirty to ninety generations ago. Assuming an average generation time of three years, that translates into just 90 to 270 years ago. In addition to these more recent genetic bottlenecks, the DNA of modern dogs also held traces of a much more ancient bottleneck: one that was presumed to result from the original domestication of some grey wolves – into dogs. The geneticists estimated that this bottleneck occurred around 9,000 generations ago – around 27,000 years before the present.
This potentially early date for domestication prompted archaeologists and palaeontologists to wonder if they’d been missing something, and one group of researchers set out to examine that possibility. They looked at nine skulls of large canids – animals that could have been either dogs or wolves – from sites in Belgium, Ukraine and Russia, dating to between around 10,000 and 36,000 years ago. They didn’t make any assumptions about whether these skulls did in fact represent wolves or domestic dogs. Instead, they made careful measurements and then compared the data from the ancient skulls with a large sample of more recent canid skulls, including obvious examples of dogs and wolves. Five of these ancient skulls appeared to be wolf. One was impossible to pin down. Three were closer to dog than to wolf. Compared with wolves, these canids had shorter, broader snouts, and slightly wider braincases. One of these ancient dog skulls was very old indeed. It was from Goyet Cave in Belgium, which has proven to be a treasure trove of Ice Age artefacts, including shell necklaces and a bone harpoon, as well as bones from mammoth, lynx, red deer, cave lion and cave bear. The cave had clearly been used by humans and animals for thousands – perhaps even tens of thousands – of years. But it was possible to pin a precise date on the putative dog skull, using radiocarbon dating. It was around 36,000 years old – the oldest known dog in the world.
What was particularly interesting about Goyet was that this early dog had a skull shape that was quite distinct from that of a wolf. The palaeontologists who carried out this study argued that this distinct ‘dogginess’ suggested that the process of domestication – or, at least, some of the physical changes associated with it – may have been very rapid. And once skull shape had changed – from wolf-like to dog-like – it stayed that way for thousands of years.
And yet this is a single example of what looks like an early dog, dating from before the peak of the last Ice Age. It’s so surprisingly early that it seems sensible to consider the possibility that Goyet is an aberration of some kind. Even if the dating can be trusted, couldn’t this just be a weird-looking wolf? Goyet, however, was soon joined by another, apparently very early dog. In 2011, just two years after the publication of the analysis including Goyet, a group of Russian researchers published evidence of what looked very much like another ancient dog, this time from the Altai Mountains of Siberia.
The Siberian skull was found in Razboinichya (Bandit’s) Cave – a limestone cavern tucked away in the north-western corner of the Altai Mountains. Excavations starting in the late 1970s and continuing until 1991 turned up thousands of bones, buried in a layer of red-brown sediment deep inside this cave. Amongst the bones were those of ibex, hyena and hare – and a single, dog-like skull. No stone tools were found in the cave, but some flecks of charcoal suggested that ancient people had also visited it during the Ice Age.
In the initial analysis, a bear bone from the fossil layer in Razboinichya Cave was radiocarbon dated to around 15,000 years ago – the late Ice Age. All the other bones were assumed to be of a similar age. So that dog skull could have been boxed up and swiftly forgotten about, languishing on a dusty shelf in a university or museum storeroom – yet another example of a dog from the tail-end of the Ice Age, when the world was warming up again.
But Russian scientists decided the skull deserved more careful scrutiny. Firstly, was it really a dog? The Razboinichya skull – which quickly acquired the nickname of ‘Razbo’ – was measured and compared with the skulls of ancient European wolves, modern European and North American wolves, and the crania of much more recent dogs, from Greenland, from around a thousand years ago. Those Greenlandic dogs were of a large but ‘unimproved’ type – they hadn’t gone through the genetic mill of extreme selective breeding that would produce all the weird and wonderful variety seen in modern dog breeds. Razbo was a tricky beast to pin down. Like Goyet, its snout was relatively short and broad – a dog-like characteristic. But it had a hooked coronoid process – the projection of bone on the upper mandible where an important chewing muscle, temporalis, attaches – that was more wolf-like. The length of the upper carnassial tooth – a slicing type of tooth, useful for shearing through muscle and sinew – fell within the range for wolves. But this tooth was relatively short compared with other teeth in Razbo’s mouth: it was shorter than two molars stacked together – and that’s a more dog-like characteristic. The lower carnassial tooth was smaller than that seen in modern wolves, but on the other hand, it fitted comfortably into the range for prehistoric wolves. The teeth were less crowded in the jaw than might be expected for a dog. Despite the short snout, then, Razbo’s teeth looked more wolf-like than dog-like. Yet Razbo’s skull measurements told another story – the skull shape was closer to the Greenland dogs than anything else.
Of course this was always going to be tricky. Early dogs are only just not-wolves. And while some features of anatomy and behaviour do arrive in package form, often because they depend on just a few genes, most traits will appear in a gradual, piecemeal fashion. The transformation occurs over generations: pieces of the mosaic change, little by little, until the picture is a new one. This is why Goyet was quite remarkable – two distinct changes to skull shape, in the form of a broader snout and a wider braincase – do seem to have appeared very quickly in early dogs. But we shouldn’t be alarmed at the discrepancy between skull shape and teeth in Razbo.
With a skull shape like that of a Greenlandic dog from a thousand years ago, but slicing teeth more like wolves, the Russian scientists concluded that Razbo could well have been an incipient dog – one of the earliest examples of this particular experiment in domestication. But still, a 15,000-year-old incipient dog isn’t much to bark about. There are plenty of those knocking around. It was the new dating of the skull – direct dating, using bone samples from Razbo itself, and carried out in three separate labs, in Tucson, Oxford and Groningen – that caused a stir. The skull turned out to be around 33,000 years old. Goyet was no longer alone.
Case closed, then: both bones and genes seemed to be pointing to an early date of domestication, around 30,000 years ago, give or take. Rather than being anything to do with the onset of agriculture (at its earliest, some 11,000 years ago in Eurasia) or even the changing environment and society as the Ice Age released its grip (some 15,000 ago) – it looked like humans’ best friend had much earlier origins: way back in the Palaeolithic, before the peak of the last Ice Age, before anyone lived in villages, towns or cities. When we were all still nomads, hunters and gatherers. Long before our ancestors settled permanently in the landscape.
But, unfortunately, the origins of the domestic dog were also far from settled. In 2014, another team of geneticists weighed in to the debate. Various researchers had argued for origins of dog domestication occurring in Europe, East Asia or the Middle East. So the geneticists wanted to look more carefully at the geographic origin of dogs – and to probe the question of whether a single origin or multiple origins was most likely. They sequenced the genomes of three wolves – from Europe, the Middle East and East Asia – as well as an Australian dingo, a basenji (descended from hunting dogs in western Africa) and a golden jackal. The researchers found plenty of evidence of interbreeding between different canid groups, which somewhat confused the issue. Several dog breeds contain traces of quite recent interbreeding with wolves – freely roaming village dogs, for example, probably had fairly regular contact with wild wolves. However, the geneticists were able to sift through the DNA data, looking past these more recent interbreeding events and searching for clues about the earliest dogs, hidden in the genes of their latest descendants. The genetic evidence pointed to dogs having had a single origin of domestication – and they estimated that this took place between 11,000 and 16,000 years ago. This still suggested that the domestication of dogs wasn’t linked to the advent of farming, as some researchers had previously suggested. Yet on the other hand, this later date was well after the peak of the last Ice Age, leaving Goyet and Razbo stranded on the other side, deep in time.