New Theory Links Dog Domestication And Excess Protein
A team of Finnish researchers have developed a new theory about dog domestication and the evolution of dogs from wolves. In an article appearing in the January 7 edition of the peer-reviewed journal Scientific Reports , the researchers posit that hunter-gatherers roaming the frigid and unforgiving tundra of northern Eurasia during the last glacial maximum (approximately 22,000 years ago) began feeding their excess lean-meat proteins to wolf pups they were keeping as pets. They say this practice would have created a symbiotic and cooperative relationship between humans and wolves that benefited both species, setting the stage for dog domestication as we know it today.
Reconstructing The History Of Dog Domestication
According to an article in the Smithsonian Magazine , during the bitter and hostile wintertime conditions experienced by the occupants of northern Eurasia during the last Ice Age , the competition for prey among predators would have been intense. Human intelligence would have given them some advantage, enough so that small groups of hunter-gatherers living in these areas would have been able to obtain sufficient calories to survive.
Wolves would have been viewed as competitors for prey. But they would have also been seen as potential allies, which if domesticated could offer humans assistance with hunting while providing them some protection from other predators (including rival groups of hunter-gatherers).
A wild wolf on the move looking for food and probably wondering about those hunter-gatherers all around him. (Wolf_Kolmården.jpg: Daniel Mott from Stockholm, Swedenderivative work: Mariomassone / CC BY-SA 2.0 )
In a desolate and unsparing environment, it would have been better to work with wolves than against them, and once their proclivities for bonding with humans were discovered organized attempts to domesticate them were bound to occur.
An important aspect in the evolving relationship between people and “wolves”, the Finnish researchers argue, would have been the fact that humans are less efficient at processing protein than other carnivores.
During hard winters lean meat acquired through hunting would have been the primary food source for hunter-gatherers. However, because of their physiological characteristics, humans can safely consume a maximum 45 percent of their calories from proteins. The rest must come from fats and carbohydrates, which they would have harvested from the brains, organs, bones, and lower limbs of the animal species they relied on for food in prehistoric times.
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Since ancient hunter-gatherers couldn’t consume all the lean-meat protein they obtained, a sensible choice would have been to feed it to wolves, to keep them healthy while encouraging them to become more dependent on humans for sustenance. And as time passed, evolutionary forces would have worked their magic, gradually transforming tame wolves into even tamer domesticated dogs—or so the Finnish researchers assert, in their imaginative yet science-based reconstruction of dog domestication history.
A Remarkably New Paradigm For Dog Domestication
This theory of how dogs became domesticated from wolves differs from current conventional wisdom, which relies on two competing hypotheses to explain dog domestication.
One suggests that wolves in hostile climates may have followed humans around and scavenged leftovers from their food or garbage dumping grounds. Over time, they would have crept closer and closer to human encampments, becoming friendlier and more approachable and therefore more amenable to domestication.
The other theory proposes that it was humans who followed wolves, as pragmatic-minded hunter-gatherers sought to merge their hunting activities with those of wolf packs. Such activity would have increased the odds of hunting success for both species and ultimately formed the foundation for a beautiful enduring friendship.
Scavenging wolves would have found the leftovers hunter-gatherers threw away and thus learned to follow humans. ( Patrick J. / Adobe Stock)
The Finnish researchers are skeptical of both explanations.
“In our opinion, the self-domestication in this way is not fully explained,” Maria Lahtinen, an archaeologist from the Finnish Food Authority and the lead author of the Science Reports article, told Gizmodo . “Hunter-gatherers do not necessarily leave waste in the same place over and over again. And why would they tolerate a dangerous carnivore group in their close surroundings? Humans tend to kill their competitors and other carnivores.”
In support of their theory, the researchers note that all Pleistocene-era archaeological digs that have recovered dog remains have been undertaken in areas where arctic or subarctic conditions predominated when the dogs lived.
Tundra-like conditions were the norm in much of Europe and northern Eurasia in the period between 27,000 BC and 12,000 BC, which is when the Finnish researchers believe the modern dog emerged.
Assuming key events that furthered the burgeoning human-dog relationship occurred at this time, their hypothesis represents a credible historical reconstruction, based as it is on what we know about human physiology and ancient food-gathering practices.
The Domestication Of Dogs And Timeline Questions
Among researchers who study these questions, theories about how wolves became domesticated and turned into dogs are many and myriad.
For example, at least two genetic studies of dog DNA have yielded data suggesting an earlier origin for the domesticated dog. Researchers who sponsored one such study in 2015 claimed their evidence showed dogs most likely evolved from gray wolves in South Eastern Asia about 33,000 years ago, and only migrated westward after that. In contrast, a UCLA study from the late 1990s concluded that dogs may have diverged from wolves more than 100,000 years ago, when Homo sapiens had only just begun to migrate out of Africa.
Though the theories and explanations for dog domestication vary greatly they all suggest that the proximity of man and wolf led to the relationships we know today, like this one. ( Stanislav / Adobe Stock)
Some of the fossil evidence also seems to conflict with the Finnish researchers’ theory. Ritually buried dog skeletons that were interred between 30,000 and 40,000 years ago have been discovered in multiple locations, which would push their proposed timeline for dog domestication back by 10,000 years or more.
But the varying hypotheses for how dogs became domesticated are not mutually exclusive. The total land area of the earth is approximately 57 million square miles (148 million square kilometers), with massive oceans isolating many of the land masses. The story of how tame wolf populations produced domesticated dogs may in fact vary with geography, with diverse evolutionary tracks explaining the apparent discrepancies between scientific theories.
The “wheres,” “whens,” and “hows” in Southeast Asia may have been different from those in Central Asia, the Middle East, Western Europe, and the Americas. The movements of peoples and their animals from one region to another, and the interbreeding of domesticated wolves and dogs that would accompany these relocations, adds another level of complexity to the overall picture, leaving experts with the challenge of unraveling a remarkably complicated story.
The narrative constructed by the Finnish researchers is a new entry in the domestication explanation competition. Or perhaps it is more accurate to describe their theory as yet another piece that deserves to be added to a complex, multilevel explanatory puzzle. A piece worthy of consideration because it is grounded in science and based on reasonable, well-informed speculation.
Whatever the truth of the matter, it’s clear that men and dogs have been living with and beside each other for a long time. The historical paths traveled by each species have been inextricably intertwined because they shared a remarkable symbiotic journey through space and time.
Top image: Dog domestication begins with wolf packs and how they interacted with early hunter-gatherers. Source: AB Photography / Adobe Stock
By Nathan Falde