Bitz-Thorsen J, Gotfredsen AB. Domestic cats (Felis catus) in Denmark have increased sigificantly in size since the Viking Age. Danish J Archaeology 2018;7:241-254
In the last year, the Danish tradition of hygge (pronounced "hoo-guh") has become an international sensation and the subject of many books and Internet posts. Hygge involves the creation and enjoyment of simple pleasures and lifestyle activities that promote a feeling of coziness, warmth, relaxation, and conviviality. The peak season for hygge is late fall and winter in the Northern Hemisphere, the dark and cold days around the winter solstice.
Scandinavians, especially the Danes, have the reputation of being the happiest people on earth; the hygge tradition is part of this. And what could promote hygge more effectively than curling up with a favorite cat? The adult cat's head is perfectly designed to nestle in the hollow of their human's hand, but those cat heads are bigger nowadays. In this study of the skulls and bones of adult domestic cats excavated at archaeological sites in different parts of Denmark as well as modern skeletal remains (adult mixed breed cats, 1870-present), these researchers have demonstrated that modern cats are at least 16% bigger than their Viking Age (c.850-1050 CE) forebears. Most species of animals, including the dog, decreased in size with domestication compared to their wild ancestors, but not the cat.
Very small numbers of cats were present in pre-Viking Age Denmark; feline populations increased significantly by the Viking Age. In common with many early peoples, the Vikings initially valued cats as rodent catchers on ships and farms and a source of pelts, but by the late Middle Ages, they had become cherished and well-cared-for house pets. These Scandinavian cats were originally of Egyptian lineage. Although cat trading was illegal in Egypt by 1700 BCE, somehow cats with mitochondrial DNA of Egyptian lineage made their way to a Viking trading port on the Baltic Sea by the 7th century CE. Previous archaeological research has suggested that the Egyptians cultivated the human-cat bond in ways not pursued by other civilizations, producing cats that were more desirable because more socialized to humans, including farmers, sailors, and traders.
Femur length demonstrated the largest change over time (16%) while tooth size increased the least (5.5%), from Viking Age to modern times. From the Viking Age to the Medieval period, a gradual increase in femur length was observed, although there was overlap in measurements between the Viking Age and Medieval Age cat osteological materials. More modest increases in size were identified when comparing the femurs and teeth of post-Medieval cats with those of modern female cats; over this time span, femur length only increased 4%, while dental size increased 1.5%. Due to size variation observed in the bones of Viking and Medieval Age cats, it was likely that both sexes were represented, although it was not feasible to classify these ancient materials by sex. However, only female remains were used as modern comparisons, which means that the observed increases in skeletal size represent the minimum differences between the archaeological groups and modern cats.
Food availability was considered likely to be a major factor in the body size increase observed in the study. As cats transitioned from rodent hunters and pelt providers living commensally with human settlements or on ships to house pets with a subsidized lifestyle, more of the animal's energy could be devoted to body growth rather than finding food. Genetic changes could also have played a role in the size increase, and additional studies would be required to establish this as a factor. In Denmark, ongoing interbreeding of domesticated cats with wild cats, as occurred in other parts of Europe, was very rare, as previous research has established that wild cats were no longer present in Denmark by the Early Roman Iron Age (1-100 CE). During the time of probable overlap between the presence of wild cats and domestic cats in Denmark (500 BCE-100 CE), both types of cat were present in very small numbers. Additional studies are required to determine if hybridization occurred involving these very early domestic cats and their wild conterparts. [PJS]
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