Did dogs choose to be domesticated? (Image credit: martinagebarovska via Getty Images)
Researchers still don’t know exactly how wolves became the ancestors of domestic dogs, but it’s possible that they chose to do so by coexisting with humans in order to provide themselves with a steady food source, according to a new study. As a result, these dogs, who were looking for food, likely began pairing up with the same intentions.
While the idea is not new, new research shows that there is a statistical possibility that wolves themselves initiated the process of dog domestication through natural selection.
Archaeological and genetic evidence suggests that dogs (Canis familiaris) descended from gray wolves (Canis lupus) and were domesticated in two major historical periods: from 30,000 to 15,000 years ago, when wild wolves became the first dogs, and again from 15,000 years ago to modern times, when these dogs began to diverge into breeds. These stages of domestication were driven by different evolutionary forces, according to a new study published Feb. 12 in the journal Proceedings of the Royal Society B.
The second period of domestication is thought to have been influenced largely by artificial selection: humans selected tamer wolves to accompany them on hunts and as companions, deliberately crossing less wild individuals, which eventually led to the domesticated species we know as domestic dogs.
The factors that contributed to the first stage of domestication, however, are less clear. One hypothesis is that wolves may have “self-domesticated”: after the ancestors of modern dogs began to appear in human settlements in search of scraps of food, they became more accustomed to living near people. These hardier wolves preferred a stable food source to the inconsistent supplies of the wild, and their offspring became the basis for the first domestic dogs.
A similar process is thought to have occurred with cats: research suggests that the ancestors of domestic cats lived near agricultural communities around 10,000 years ago, before developing a mutually beneficial relationship in which they hunted rodents in exchange for food.
The Dog Domestication Debate
Scientists have long debated the hypothesis of dog domestication. One of the main concerns is that natural selection may not be fast enough to transform wild wolves into domestic dogs over millennia – without human intervention to speed up the process.
In the new study, the researchers examined the time frame by using a statistical model that took into account the possible timing of dog domestication and gave computer models of dogs some freedom in their choice of lifestyle and mates.
The model showed that natural selection could have driven dogs to self-domesticate over 15,000 years. However, for this to happen, two conditions had to be met: wolves had to decide to stay close to humans to get food, and they had to choose mates with similar temperaments.
“When females chose mates, they also had to choose males that had similar levels of tameness to them,” study co-author Alex Capaldi, a mathematician and statistician at James Madison University in Virginia, told Live Science. “So if both of these processes were occurring, then the self-domestication hypothesis might be immune to the time-limited criticism.”
The scientists noted that although the model does not show specifically how wolves became domesticated, its results indicate that self-domestication is possible.
Dogs are the first animals to be domesticated, so studying their evolution can help scientists gain a deeper understanding of how domestication might occur in other species. And because the process of dog domestication was closely tied to the formation of early human societies—dogs herded livestock in the first human settlements and migrated with early humans to the Americas—understanding the timeline of this process can shed light on our own history and how we ourselves evolved to interact and bond with our own
Sourse: www.livescience.com
