The palaeogenetics of cat dispersal in the ancient world | Nature Ecology & Evolution
▻https://www.nature.com/articles/s41559-017-0139
Abstract
The cat has long been important to human societies as a pest-control agent, object of symbolic value and companion animal, but little is known about its domestication process and early anthropogenic dispersal. Here we show, using ancient DNA analysis of geographically and temporally widespread archaeological cat remains, that both the Near Eastern and Egyptian populations of Felis silvestris lybica contributed to the gene pool of the domestic cat at different historical times. While the cat’s worldwide conquest began during the Neolithic period in the Near East, its dispersal gained momentum during the Classical period, when the Egyptian cat successfully spread throughout the Old World. The expansion patterns and ranges suggest dispersal along human maritime and terrestrial routes of trade and connectivity. A coat-colour variant was found at high frequency only after the Middle Ages, suggesting that directed breeding of cats occurred later than with most other domesticated animals.
The domestic cat is present on all continents except Antarctica, and in the most remote regions of the world, and its evolutionary success is unquestioned. While it is nowadays one of the most cherished companion animals in the Western world, for ancient societies barn cats, village cats and ships’ cats provided critical protection against vermin, especially rodent pests responsible for economic loss and disease . Owing to a paucity of cat remains in the archaeological record, current hypotheses about early cat domestication rely on only a few zooarchaeological case studies. These studies suggest that ancient societies in both the Near East and Egypt could have played key roles in cat domestication .
Wildcats (Felis silvestris) are distributed all over the Old World. Current taxonomy distinguishes five wild, geographically partitioned subspecies: Felis silvestris silvestris, Felis silvestris lybica, Felis silvestris ornata, Felis silvestris cafra and Felis silvestris bieti. Modern genetic data analyses of nuclear short tandem repeats (STR) and 16% of the mitochondrial DNA (mtDNA) genome in extant wild and domestic cats revealed that only one of them, the north African/southwest Asian F. s. lybica, was ultimately domesticated.
Wildcats are solitary, territorial hunters and lack a hierarchical social structure, features that make them poor candidates for domestication. Indeed, zooarchaeological evidence points to a commensal relationship between cats and humans lasting thousands of years before humans exerted substantial influence on their breeding. Throughout this period of commensal interaction, tamed and domestic cats became feral and/or intermixed with wild F. s. lybica or other wild subspecies as is common today. These regular genetic exchanges may have contributed to the low level of differentiation observed between modern wild and domestic cat genome sequences. Accordingly, the domestication process seemingly has not profoundly altered the morphological, physiological, behavioural and ecological features of cats, in contrast to what has been observed, for example, for dogs.
To address questions related to the contribution of the two purported centres of cat domestication, the Near East and Egypt, and the history of human-mediated cat dispersal, we analysed ancient and modern cats from Europe, north and east Africa, and southwest Asia (SWA), spanning around 9,000 years, from the Mesolithic period to the twentieth century AD. We analysed ancient DNA (aDNA) to explore whether a fine phylogeographic structure of maternal lineages existed prior to the domestication of F. s. lybica and whether, when and how it was reconfigured over time in response to human intervention, thereby documenting the domestication process of the cat. We also studied a genetically defined coat-colour marker, the blotched tabby marking, to monitor a phenotypic change reflecting human-driven selection along the domestication pathway.
Figure 2: Spatio-temporal representation of the alleles determining the phenotypic variation in the shape of tabby patterns, mackerel (Ta^M) and blotched (Ta^b).
To overcome issues of potential allelic drop-out, each individual is defined by at least one observed allele, except for the few instances in which both alleles were detected.
The image shows a ‘cat under the chair’ with a tabby mackerel marking, typical of F. silvestris lybica (Anna (Nina) Macpherson Davies, Copy of Wall Painting from Private Tomb 52 of Nakht, Thebes (I, 1, 99–102) Cat Eating Fish. Photo: © Ashmolean museum, Oxford, UK).
