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Popular Science: A dog or a wolf?

There is a well-known saying that ‘a dog is man’s best friend’ and nowadays we often see that it can be true. Even though dogs are our best friends, there are still a lot of things we do not know about them. For example, when did they become our best friends? In other words, when did wolves begin their transformation from a feared predator into our best friend, the dog? A team of scientists, including Martina Lázničková-Galetová from Hrdlička Museum of Man (Charles University, Faculty of Science) and Moravian Museum in Brno, tried to find an answer to this question. With the help of the latest technology the scientists analysed the microstructure of teeth samples from the Předmostí Palaeolithic site. This study follows up research focusing on the evidence of one of the earliest occurrences of domestications of wolf.

Dog was the first animal that was domesticated by humans. This first domestication took place even before people adopted agriculture, which is a crucial change in human lifestyle linked with domestication of other animal species. Even though this first domestication has been thoroughly studied, its timing is still unclear. Proposed estimates range from 15,000 to over 41,000 BP. But the timing of the first domestication and its nature are of special interest because the long-term coexistence of dogs and humans shaped ecology, behaviour and cognition (the way an individual acquires, processes and uses information from its surroundings – ed. note) of these two species.

Comparison of dog-like (top specimen) and wolf-like (bottom specimen) mandibles from Předměstí site.

Both morphological and genetic data confirm that domestic dogs (Canis familiaris) are descendants of Eurasian wolves (Canis lupus). The scavenging hypothesis suggests self-domestication of dogs by scavenging for human food scraps, mostly prey carcasses. Exploitation of human-produced waste is a learned behaviour that can sometimes be observed in coyotes, foxes, wolves and free ranging dogs. Frequent close vicinity of wolves and humans would have decreased inherent fear of humans and further facilitated consumption of scraps. This probably resulted in a series of mutualistic proto-domestication processes and slow shifts in the human-canid relationship.

Morphological (form and structure of organisms – ed. note) and morphometric analyses (quantitative analysis of size and shape – ed. note) suggest differences between dogs and wolves, especially in the shape of mandibles and in teeth modifications. These differences reflect the dietary behaviour of the two species. The short robust mandible of dogs is specialized to break bones.

Differences in dietary traces on dentition (microwear structure) of a dog (top row) and a wolf (bottom row), comparison of a carnassial tooth (first column) and the second molar (second column).

Feeding on bones should also be reflected on dentition, leaving distinct scratches, which can be revealed using Dental Microwear Texture Analysis (DMTA). This approach combines fractal geometry and confocal light microscopy to detect traces of dietary evidence left during the days to weeks prior to an individual’s death. DMTA is used for example for reconstruction of dietary behaviour of extinct taxa or it can provide insights into cryptic (morphologically indistinguishable – ed. note) species. In carnivorous species, this technique can be used for distinguishing flesh specialists from those that consume bones (which are hard and brittle). And because morphological changes are quite slow in comparison with behavioural changes, this analysis can identify changes in diet that occur prior to morphological changes, in this case increased consumption of bones connected to domestication.

The authors of this paper analysed samples from 20 mandibles from Předmostí, which is an open-air site in the Moravian Corridor (Czech Republic), dated to Upper Palaeolithic (28,500 BP – calibrated date). This site is known for large skeletal accumulations of mammoths, canids (dogs and wolves) and humans. Scientists studied 20 canid mandibles housed in an off-site repository of the Moravian Museum in Brno (Czech Republic). When performing the dental microstructure analysis, they focused mainly on the carnassial teeth – the first molar, or M1, which is responsible for tearing of meat, and the second molar (M2), which is specialized for crushing bones. Traces on the second molar should, therefore, represent a key for distinguishing between canid diets and therefore between wolves and dogs.

The results of this study show that dietary traces left on the second molar (M2) indeed indicated whether the studied specimen was a wolf of a dog. One type of mandibles had molars which showed larger microwear features and lack of smaller ones. This pattern is consistent with greater consumption of hard and brittle foods, indicating a dog-like diet. The second type of mandibles did not have such large scratches on the teeth, which is consistent with the feeding habits of wolves. Even though these results are convincing and in accordance with the results of previous studies, authors point out the need of additional research to support the statement that the specimens they studied were really diverging wolf and dog, and not two distinct types (species or populations) of wild canids.

Prassack, K. A., DuBois, J., Lázničková-Galetová, M., Germonpré, M., & Ungar, P. S. (2020). Dental microwear as a behavioral proxy for distinguishing between canids at the Upper Paleolithic (Gravettian) site of Předmostí, Czech Republic. Journal of Archaeological Science115, 105092.

Veronika Rudolfová

Published: Jul 23, 2020 06:40 PM

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