We’ve known for some time that dogs were domesticated from wolves in Eurasia at least 12,000 years ago. One of the mysteries, however, is how they physically changed and specialized for tasks like guarding and herding in prehistoric times.
Now, a paper co-authored by researchers at UC Santa Barbara examines archaeological data to claim that when Neolithic farmers spread to Europe, they brought with them dogs that grew larger by the age of the bronze and iron. Additionally, remains from the eastern Adriatic region of present-day Croatia strongly suggest that changes in dog bodies reflect an evolution in the relationship between these early canids and humans.
“We tend to think of human-dog relationships as static over time, but what we’ve found is that there seems to be a shift in the way humans interact with dogs, even in these small-scale agricultural societies,” said Sarah McClure, associate professor. and chairman of the Department of Anthropology. “We argue in the paper that this change is likely the result of shifts in multi-species relationships – humans, sheep/goats, and dogs – and how they are intertwined.”
McClure explained that changes in the use of dogs for livestock management have also changed the selective pressures on the dogs themselves, and humans have likely begun to breed dogs differently to select for traits that aid in herding. and raising cattle.
“So the change in the relationships between species (humans, dogs, sheep/goats) also resulted in biological changes in dogs that we can measure by analyzing bones from archaeological sites,” she said.
Indeed, the researchers’ ability to estimate body mass in the absence of more complete remains is a game-changer in reconstructing the development of dogs over time. Previously, shoulder height was used to assess changes in dog populations. But it is rare to find remains complete enough to make this kind of assessment.
McClure said the work of Martin H. Welker of the University of Arizona, the paper’s lead author, made such assessments possible.
“It’s work that Martin has developed over the years, building on established methods of analyzing animal remains,” she said. “Estimating body size from scattered bone fragments is really exciting and it is precisely what has allowed us to determine changes over time in addition to the cut marks and diet differences that we have identified through to stable isotopes.
Nick Triozzi, a Ph.D. in anthropology from UCSB. candidate who contributed to the study, said that stable isotope analysis did not reveal much about the development of our relationship with dogs. But the bigger picture became apparent when Welker compiled a wider range of stable isotope data and looked at physical changes in Croatian dogs over several thousand years.
“These changes in diet and physical size are particularly compelling in the context of what we’ve learned about subsistence and economics through archaeological research,” Triozzi said. “So what’s really interesting about this article is how lab analysis and archeology have been combined to tell us more about how human-dog interactions have developed over time. As humans became more dependent on herding larger numbers of livestock, humans found a new use for dogs that previously served to protect livestock from predators.
The development of pastoralism also seems to have played an important role in the size of dogs. The article suggests that their larger size is correlated with increased transhumance – movement of livestock between pastures depending on the season. As the practice increased in the Bronze and Iron Ages, archaeological records show that the dogs grew larger. Additionally, isotopic analysis revealed that dogs ate what humans ate after Neolithic times, suggesting a closer relationship between the two species.
“These new activities created a different need for what a dog should look/act to perform this function,” McClure said. “This created selective pressures that caused larger dogs to become more common among those small farmers who had larger herds that they moved and herded, expanding the different types of dogs among human communities.”