New theory: dogs were domesticated because they were able to take advantage of higher levels of protein consumption than humans

January 7/2021

The domestication of wolves into dogs was only possible in cold climates, according to a recent study published in Scientific Reports.

Dogs were the only species known to have been domesticated by hunter-gatherers. Why dogs were domesticated has not been comprehensively explained in the past.

“In the study, we concluded that in cold climates, the ecological competition between humans and wolves for food was diminished during winter months. Thus, the lack of competition between the two species means that hunter-gatherers could have kept wolves as companions for several generations making the process of domestication possible,” says Senior Researcher Maria Lahtinen-Kaislaniemi from the Finnish Food Authority and the University of Helsinki.

Wolves were domesticated into dogs during the last ice age at least 15,000 years ago or even earlier. Some evidence suggests that domestication occurred several times across Eurasia.

Two theories about the domestication of dogs

Until today, the domestication of wolves has been explained in two ways. Wolves developed into a less fearful primitive dog living off human food waste or, according to another theory, were domesticated as hunting partners.

“Both explanations have their problems, because people during the ice age were mobile and did not constantly leave waste in the same place. Without a permanent landfill, it is difficult to argue that dogs were domesticated from wolves that lived off human waste heaps,” says Lahtinen-Kaislaniemi.

On the other hand, it has been shown that dogs are most helpful in hunting outside the wolves’ natural habitat. In addition, a hunting partner is most useful only when it has already been domesticated. Thus, dogs could not have been tamed for the purpose of improving hunting performance. Which further ponders why humans would have tolerated a predator in their vicinity.

The study presented a new theory about the cause of dog domestication, based on food distribution

“It is reasonable to assume that wolf pups could have been taken as pets because modern hunter-gatherers are known to take juvenile wild animals as pets today. However, these “pets” do not become truly domesticated. This is because keeping pets for several generation will normally lead to competition between humans and their “pets”. In other words, in a crisis or during times of diminished resource availability, as Palaeolithic communities must have experienced during Ice Age winters, people prioritize feeding themselves over their pets,” Lahtinen-Kaislaniemi says.

The study showed that humans living in artic and subarctic areas cannot consume large portions of lean meat from hunted prey. Animals lose weight in winter, becoming low in fat, and there are no carbohydrate-rich plants available either. Therefore, people were able to utilize only parts of animals with the most fat. The ability of wolves to digest protein is significantly better than ours, so primitive dogs and Palaeolithic humans would not have been in competition over food during winter months critical for survival.A map where find locations of dogs are presented.The study involved Maria Lahtinen-Kaislaniemi (Finnish Food Authority and University of Helsinki), Suvi Viranta-Kovanen (University of Helsinki), Kristiina Mannermaa (University of Helsinki and University of Tartu), Sakari Salonen (University of Helsinki and University of Bordeaux), and David Clinnick (University of Durham and Saint Mary's College of California).

Research team.


Lahtinen, M., Clinnick, D., Mannermaa, K. et al. Excess protein enabled dog domestication during severe Ice Age winters. Sci Rep 11, 7 (2021). DOI:

Further information:

Senior Researcher Maria Lahtinen-Kaislaniemi, Finnish Food Authority, tel. +358 50 339 4493,

Docent Suvi Viranta-Kovanen, University of Helsinki, tel. +358 40 715 4918,