The question of why dogs were domesticated has been long debated without any conclusive arguments. Here is a new hypothesis by Maria Lahtinen of the Finnish Food Authority in Helsinki and coworkers.

Humans are primates with ancestors that were herbivores and insectivores, and therefore unusual carnivores with a limited capacity to digest protein. Unlike humans, wolves can, because of their evolutionary history as carnivores, sustain in the short-term on a solely protein-based diet. In harsh Ice Age winters, to get enough fat hunters had to kill more lean animals like deer and moose than they could eat in their entirety. So Ice Age hunters could fed the excess meat to wolves.

Humans domesticated wild wolves at some point between 14,000 and 29,000 years ago. They present data showing that all the Pleistocene archaeological sites with dog or incipient dog remains are from areas that were analogous to subarctic and arctic environments.

Dogs (Canis familiaris) are the first animals to be domesticated by humans and the only ones domesticated by mobile hunter-gatherers. Wolves and humans were both persistent, pack hunters of large prey. They were species competing over resources in partially overlapping ecological niches and capable of killing each other. How could humans possibly have domesticated a competitive species? Here we present a new hypothesis based on food/resource partitioning between humans and incipient domesticated wolves/dogs. Humans are not fully adapted to a carnivorous diet; human consumption of meat is limited by the liver’s capacity to metabolize protein. Contrary to humans, wolves can thrive on lean meat for months. We present here data showing that all the Pleistocene archeological sites with dog or incipient dog remains are from areas that were analogous to subarctic and arctic environments. Our calculations show that during harsh winters, when game is lean and devoid of fat, Late Pleistocene hunters-gatherers in Eurasia would have a surplus of animal derived protein that could have been shared with incipient dogs. Our partitioning theory explains how competition may have been ameliorated during the initial phase of dog domestication. Following this initial period, incipient dogs would have become docile, being utilized in a multitude of ways such as hunting companions, beasts of burden and guards as well as going through many similar evolutionary changes as humans.

Lahtinen, M., Clinnick, D., Mannermaa, K., Salonen, J.S., and Viranta, S. (2021). Excess protein enabled dog domestication during severe Ice Age winters. Scientific Reports 11, 7.

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Features Image: A map of vegetation zones during the Last Glacial Maximum and Palaeolithic dog remain discoveries (Op. cit.)