Did Dogs Choose Us?

Helen Pilcher on the Interspecies Bond That Changed History

Please don’t judge me. I am about to tell you something you may find shocking, and I am concerned you may think badly of me. When I’ve told people before, it has divided opinion. Some have been curious, others downright disgusted. They’ve told me it’s unnatural and asked me how I could do such a thing. I’ve no idea how you’ll react, so I’ll just come straight out and say it.

I own a genetically modified wolf.

I really do. My husband and I got him from a breeder that we found on the Internet. We exchanged a couple of emails, transferred a hefty wedge of cash then collected him from a pre-arranged location in southern England. The little animal howled all the way home.

Five years later, we now trust him so much that he lives in our house, sleeps on our bed and plays with our kids. If we were to set him free, I’m almost certain he wouldn’t survive. He’s never hunted fresh meat or brought down a caribou. He’d probably hang around by our back door, sulk and wait to be let back in again.

Higgs, as we call him, is a weird-looking wolf. His DNA has been altered so he is less than half the size of his free-roaming ancestors. His skull is smaller, his snout less pointy and his ears flop down rather than standing erect. The classic sleek pelt has been replaced with what can only be described as an embarrassment of soft, messy curls. He is black all over, except for his nose, belly, tail and feet, which are white… or brown when he’s been digging in the garden. His tail wags rhythmically when he hears the word “cheese.” Behaviorally, all trace of wolf cunning has been obliterated. The result is an animal so far removed from its original wild form that he barks at bin bags and often refuses to go out in the rain.

Before you pass judgement on this apparent lupine freak, let me tell you I am not the only one to own a genetically modified wolf. Millions of people, all over the world, keep similar animals but know them by a different name. They call them dogs. For dogs are genetically modified wolves.

When people think about genetic modification (GM), they tend to think about animals and plants whose DNA has been sculpted using the modern tools of genetics, but domesticated species have been genetically manipulated too. From the diminutive dachshund to the massive Saint Bernard, all dogs are descended from the European grey wolf. At some point in the past, humans and wolves crossed paths, and then somehow, somewhere, the wolf began to change. Its appearance altered. The wolf began to shrink. Its coat changed color and its face changed shape. Physiological differences emerged, like the ability to digest starch and give birth more often. Its behavior changed. The fearsome apex predator morphed from an animal that actively shuns human company into one, like Higgs, that demands it. All of these differences are underpinned by changes to the wolf’s genetic code. Now, although wolves and dogs still share around 99.5 per cent of their DNA, the tiny fraction that is different is enough to imbue them with their vastly different features.

We didn’t invite wolves in, but by being messy, we created an ecological niche they were only too happy to fill.

Today, dogs have become such a normal part of our lives that it’s easy to take them for granted, but their emergence marks a defining moment in the natural history of our world. Dogs were the first domesticated animals. It was the first time humans took a species and then fashioned it to become something more preferable. It was the first time we wrestled control of evolution and began to steer the biology of living things in a different, post-natural direction.The emergence of dogs paved the way for other domesticated species to follow, triggering a chain of cause and effect that would change our world for ever.

According to the most recent estimates, modern humans evolved in Africa sometime between 350,000 and 260,000 years ago, and for the vast majority of the time that followed, we simply lived off the land. We existed as hunter-gatherers, and were entirely dependent on wild animals and plants for our survival. Domestication changed all that. Around 10,000 years ago, after we had domesticated dogs, we began to strike up alliances with other wild organisms. The repeated harvesting and sowing of wild cereals led to the creation of domestic crop strains that were more bountiful and easier to grow. We domesticated other animals, like sheep, cows and goats, and as we began to corral and keep them, and tend to our crops, we found ourselves increasingly tied to the land. The nomadic hunter-gatherer way of life gave way to a more settled existence, leading to the formation of villages. Because they could be bred, domestic animals provided a renewable source of meat and milk for food, and wool and leather for clothing. Food became more plentiful and the population began to grow. In time, because they could be owned and were easily transportable, domestic animals and plants went on to become a source of capital and wealth, so domestication fueled the rise of trade. It drove the development of new technology, like ploughs, which further accelerated the rise of agriculture and in time led to the development of urban communities. When we think about key innovations, it’s all too easy to dwell on recent inventions like the Internet and antibiotics, but it’s no understatement to say that domestication helped to fuel the rise of civilization, and changed the course of human history.

Looking around me now, I see a world full of domesticated species. My genetically modified hound, Higgs, slumbers peacefully at my feet. In the garden outside, our five chickens peck at corn, while our two rabbits nibble on a carrot. There are ponies in the field next door, and sitting on the fence post, a wayward tabby cat eyes me with disdain. Sitting at my desk sipping milky tea,* it’s hard to imagine a time when the world was not full of domesticated animals, plants and the products derived from them. Yet, for the vast majority of time that there has been life on Earth, there have been no domesticated animals or plants. So when and where did this momentous change take place?

Until quite recently, scientists thought dogs were domesticated around 15,000 years ago, towards the end of the last Ice Age. It was a time when the ice sheets were retreating, when the landscape was newly green, and when humans and other animals began to colonize the northerly regions of Europe and Asia. There are plenty of dog fossils from this time, found in archaeological sites across Europe, Asia and North America, and the scientists who have studied them all agree: these remains belong to dogs, not wolves. The proportions of their skulls and the shapes of their teeth are all quite different. But then came a fossil that left people scratching their heads.

The skull was discovered in the Goyet Cave in Belgium. It’s a remarkable archaeological site jam-packed with the bones of ancient humans, Ice Age animals and other captivating relics. “The skull is quite small,” says Mietje Germonpré from the Royal Belgian Institute of Natural Sciences in Brussels, who studied the fossil. “It is about the same size as a modern German Shepherd skull.” Wolves have long, slender snouts, but this animal had a shorter, wider muzzle and a broader braincase. It also had large, primitive-looking teeth. Collectively the features suggested that this animal was more dog than wolf. “So we decided it was a primitive dog,” she says.

Then came the bombshell. Radiocarbon dating revealed that the skull was actually much older than previously thought. The creature was 36,000 years old, potentially pushing back the origins of domestication by a staggering 21,000 years. “We were very surprised when we found out,” says Mietje. The skull divided opinion.

Some people agreed with Mietje. Others did not. “They said it’s too old and they don’t consider it to be a dog,” she says. Critics pointed out that wolf skulls from this time vary enormously in size and shape and suggested that the Goyet skull belonged to an odd-looking wolf rather than an early dog. Then a different group of researchers made a computer-generated 3D reconstruction of the skull and concluded that certain features, like the way the snout protruded from the skull, were also wolf-like. It could have been an end to the debate, but then other fossils cropped up. Mietje has studied dog-like skulls from the Czech Republic and Russia that are over 25,000 years old, while a separate research group has described the 33,000-year-old skull of a presumed dog found in Siberia’s Altai mountains. What to think?

It’s bound to be tricky. If these animals really are early dogs, then they’re “only just” dogs so they’re bound to have dog- and wolf-like features. So it’s here that scientists are turning to another form of historical evidence to help resolve the conundrum: ancient DNA.

Back in camp, the animals would have been kept for pragmatic purposes. As cubs, they could have entertained the children.

Although DNA breaks down after death, sometimes the molecule can be preserved inside fossils, and extracted and studied.This gives scientists another way of studying the transition from wolf to dog. In the early days, genetic analyses painted a confusing picture. One study, for example, compared the full genetic sequences, or genomes, of modern dogs and wolves, to determine that dogs were domesticated between 11,000 and 16,000 years ago.Another study of ancient canids, which focused on a subtype of DNA hidden in the cells’ energy-generating mitochondria, suggests a date between 19,000 and 32,000 years ago. The results present a massive discrepancy. On the one hand, they suggest dogs were domesticated around the end of the last Ice Age at a time when agriculture was emerging. On the other, it seems they were established on the other side of the Last Glacial Maximum, the time when the ice sheets were at their greatest reach.

The debate moved on in 2015 after Swedish researchers discovered a fragment of rib protruding from a Siberian riverbank. They originally thought the bone belonged to a reindeer, but DNA analysis later confirmed that it came from a wolf. Radiocarbon dating suggested that the animal died around 35,000 years ago, long before dogs were thought to be domesticated, but then further genetic tests muddied the waters. The ancient wolf seemed to be equally related to both modern domestic dogs and modern wolves, but how could this be if dogs had yet to evolve? The team concluded that the ancient wolf must have lived just after the split between the ancestors of today’s dogs and the ancestors of modern wolves. This means an earlier date of domestication, around 35,000 years ago, looks increasingly likely. Then in 2017, a different group of researchers arrived at a similar conclusion, this time using Neolithic dog fossils.

As more studies are added, an early date for the metamorphosis of wolves into dogs looks increasingly likely. Genetic analyses and fossil evidence hint at a deep connection between humans and dogs that stretches back much further than was initially assumed. It predates the rise of agriculture and settled societies, and now researchers find themselves arguing over when and where the transition occurred.

Today, the grey wolf is the only member of the canid family to have paws in both the Old and New Worlds. Its current range encompasses much of Europe, Asia and North America, but in the past, its territory was even greater. This makes it hard to know where to start. We know that dogs cannot have been domesticated in North America, because humans didn’t arrive there until well after the Last Glacial Maximum when domestication was already well under way elsewhere, but that still leaves much of the globe to consider. Fossil finds point to Europe and further east to Siberia where the earliest, most primitive dog skulls have been found, but ancient DNA studies throw up alternative scenarios. Some suggest dogs became man’s best friend in East Asia, while others hint at origins in Central Asia or the Middle East. Meanwhile, a recent study that compared genetic material from modern and ancient specimens revealed an old, deep split between East Asian and Western Eurasian dogs. The most obvious explanation, according to the study’s author, Greger Larson from the University of Oxford, is that domestication occurred in at least two different places.The story of dogs may have no single origin. Dogs could have been domesticated multiple times in multiple places.

What intrigues me most, however, is how this relationship began. We can be pretty certain that our ancestors didn’t just wake up one day and declare they wanted something that would fetch a stick, yet the process of domestication had to begin somewhere.

*

The winter had been cold and long, but now the sun climbed higher in the sky and leaves were beginning to unfurl.The youngster sat on his haunches, staring into the embers of a fire that was dying down. He felt resentful. Not quite a boy, but not yet a man, he had been left behind in camp while the adults went out to search for food. Now he found himself alone, contemplating mischief.

A few days earlier he had followed his father out of the camp and into the woods. His father showed him a place where a large tree had fallen, wrenching deep-seated roots out of the rust-colored earth, and the resultant hole that had been exposed in the hillside. Sharp-clawed paw prints framed the entrance to a dark tunnel: the unmistakable signature of a she-wolf’s den. “Be careful,” his father had warned him. “These animals are dangerous.” Back in camp, the boy knew he had hours before the hunting party would return, so he picked up a spear and slipped out of camp. He returned to the den to find fresh scats on the ground outside. The mother wolf had been there but when she heard his clumsy footsteps, she had beaten a swift retreat. Now she hovered in the background, watching as the human dropped to his knees and plunged his arm deep into the lair. When he stood back up, he was holding a small, wriggling wolf cub. It squirmed and whined, making the boy tighten his grip.

Then he swaddled his find in a reindeer hide and carried it back to camp.

Although humans and wolves have shared the same landscape for many tens of thousands of years, they interacted little. Both would have been wary of the other and kept their distance, but then something must have changed. Academics argue over the nature of this initial interaction, but one scenario is that humans actively decided to invite the wolf into their world. Someone, like our Palaeolithic boy, went out and collected a cub. Skilled hunter-gatherers with an in-depth knowledge of their local environment, they would have known where the wolf dens were. It wouldn’t have been difficult to scoop one up and bring it back to camp. Then, having done it once, it would be all too easy to repeat the process. The cubs that were kept would inevitably have been the ones that were easiest to catch, so over time, as the genes for their more relaxed nature were passed through the generations, domestication got under way.

Back in camp, the animals would have been kept for pragmatic purposes. As cubs, they could have entertained the children. As adults, they could have acted as sentries, and if they ever got too boisterous or aggressive to look after, they could have been set free or killed for their meat and fur.

We certainly know that Palaeolithic people wore specialized cold-weather clothing, including a variety of fitted garments made from well-tanned pliable hides. A 24,000-year-old ivory figurine from southern Siberia, for example, depicts what seems to be an individual wearing a carefully tailored all-in-one fur suit. Evidence for a wolf-fur onesie? It’s a possibility. Similarly ancient wolf bones have been found with distinctive cut marks, indicating that the animals were probably skinned for their fur.They may also have held symbolic significance. One skull, studied by Mietje, is interesting because it has a bit of mammoth bone wedged between its front teeth. The fragment must have been inserted into the animal’s mouth after it died, suggesting human intervention, while other skulls sport conker-sized holes where their brains were removed. There were easier meals to be had than brain, so Mietje thinks these unusual relics are evidence that dogs held special significance. “I’m in favor of the active involvement of the Palaeolithic people,” she says. “I think they actively started to collect these animals and then kept them, not just for their fur, but for rituals too.”

It is, perhaps, easiest to imagine that humans chose the wolf, and that the wolf had no option but to go along with our plans. As a species, we like to think we are superior and separate from the animal kingdom, when really we’re just animals too. Today, if we want a dog, we can just go out and get one, but it would be naive to presume that our ancestors followed the same thought process.

So an alternative theory proposes, not that humans chose wolves, but that wolves chose humans. Leftovers discarded by humans lured the wolves out of the shadows. The animals that were least afraid of us were the ones most likely to enter our campsites. As a result, they were better fed, healthier, and more likely to reproduce than warier pack members. The genes underpinning their more relaxed nature were passed between generations, and over time, the animals became progressively tamer. In this “self-domestication” scenario, humans were stooges. We didn’t invite wolves in, but by being messy, we created an ecological niche they were only too happy to fill.

It’s a possibility. Modern wolves are adaptable animals. In Canada, there are two types of wolf: “nomadic” wolves that follow the caribou around and “sedentary” wolves that tend to stay in one place. From time to time, their paths cross, but they don’t really get on. They’re like the Starks and the Lannisters, and will fight each other to protect what they consider to be their caribou. So maybe, 35,000 years ago there were one or more groups of migratory wolves that considered us to be their property. Instead of tracking caribou or reindeer, they followed us around, not because they wanted to eat us but because they benefited from the shared association.

So which was it? Did humans choose wolves or did wolves choose humans? We’ll probably never know but the upshot was the same.After contact was made, humans and wolves began to interact and over time, the relationship strengthened. Primitive dogs probably accompanied humans on their hunts and so tipped the odds in favor of a kill—a reciprocal arrangement that benefited both parties. At some point, when we started to physically keep them with us, we would have started engineering which animals got to reproduce. In the early days, it would have been the calmer animals that would have tolerated living in captivity, but in later times we would have selected for other characteristics, like being a good sentry or scaring the neighbors. It was the beginning of a long and beautiful friendship, and a defining moment in the story of evolution. Of course, dogs were only the beginning.

__________________________________

life changing

From Life Changing by Helen Pilcher. Used with the permission of Bloomsbury. Copyright © 2020 by Helen Pilcher.

Helen Pilcher
Helen Pilcher
Helen Pilcher, author of Life changing, is a tea-drinking, biscuit-nibbling science and comedy writer. She has a PhD in Cell Biology from London's Institute of Psychiatry. A former reporter for Nature, she now specializes in biology, medicine and quirky off-the-wall science, and writes for outlets including New Scientist and BBC Focus. Unusually for a self-proclaimed geek, Helen also used to be a stand-up comedian before the arrival of children meant she couldn't physically stay awake past 9pm. She now gigs from time to time, and lives in rural Warwickshire with her husband, three kids and besotted dog.





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