Feeding leftover meat to wolves during harsh winters may have played a role in the domestication of dogs more than 14,000 years ago, scientists believe.
Their research, published in the journal Scientific Reports, is based on an analysis of how much lean meat Eurasian hunter-gatherers would have been able to consume.
Dogs are descendants of wolves and were the first animal to be domesticated by humans. It is thought that humans living during the last Ice Age – somewhere between 14,000 to 29,000 years ago – were in direct competition with wolves when it came to hunting prey.
The researchers speculate that if wolves and humans had hunted the same animals during harsh winters, humans would have killed wolves to fend off competition rather than tame the creatures. This then raised the question: how did humans domesticate a competitive species?
A team of experts led by Dr Maria Lahtinen, a scientist at the Finnish Food Authority in Finland, looked at the energy content of the food – such as horses, moose and deer and weasels – both humans and wolves would have preyed on during that time.
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The energy content of the food was calculated by measuring the caloric intake of its protein and fat components. Findings showed that all prey species would have supplied more protein than humans could consume.
According to the researchers, this is because humans are not fully adapted to a carnivorous diet and are only able to digest about 20 per cent of their energy needs from protein. Wolves, on the other hand, can thrive on lean meat for months.
The authors believe that humans may have fed excess lean meat to wolves, “which may have enabled companionship even during harsh winter months”. They say that at some point humans began using pet wolves as hunting companions and guards, thus facilitating the domestication process even further.
The authors wrote: “We suggest that the differences between dietary constraints of wolves and humans enabled dog domestication in harsh environments in the Late Pleistocene.
“Excess protein decreased dietary competition and enhanced the possibility of sympatric existence. This could have been a significant impetus for wolves to become ‘our best friend’.”
Reader Q&A: Can I raise my dog or cat as a vegan?
Asked by: Josie Lott, london
It’s theoretically possible for dogs, but difficult in practice.
Dogs have co-existed with humans for at least 14,000 years and have evolved some extra digestive enzymes that help them to digest plant starches, probably as a result of sharing our food. But a 2015 study at the University of California, Davis, found that 25 per cent of commercial vegetarian dog foods lacked the right balance of essential amino acids. And homemade diets are even worse: a 1998 study found that 50 per cent of dogs fed homemade vegetarian or vegan food had dietary deficiencies.
For cats, it is even harder to balance. Cats are entirely carnivorous in the wild, and there are several amino acids only found in meat, such as taurine, that they can’t synthesise or store, so a vegan cat diet has to be very carefully tailored to their age and body weight.
Too little taurine can cause blindness and heart failure, while too much can lead to serious urinary tract infections. Carnivorous cats absorb all the taurine they need from meat, but synthetic taurine added to vegan food comes in several different forms, which are absorbed by the cat’s metabolism at different rates. This makes it extremely difficult to give cats a balanced vegan diet.