Despite being small and adorable, Chihuahuas are notorious for their unique temperament, exhibiting barking, tremors, high energy, and occasionally biting the lower limbs of humans. The reason for this behavior in dogs weighing under three kilograms has not yet been fully elucidated by the scientific community.
A recent investigation conducted by Stanford University, located in the United States, sought answers by analyzing Chihuahua DNA and discovered a surprising finding: these dogs possess DNA segments in common with wild coyotes. The results of this research were published in July in the scientific journal Nature Communications.
Scientists employed software using the LAI (Local Ancestry Inference) technique, which works by examining a species' genome and comparing it with that of other animals to identify shared ancestors.
The study focused on the genetic material of Chihuahuas and Xolos, both recognized as Mexican dog breeds. Previous research had already indicated that these animals possessed unusual genetic traits, suggesting the need for more in-depth studies.
While most domestic dogs in the Americas descend from European species brought during colonization, losing much of their pre-Columbian characteristics, Xolos and Chihuahuas retain genetic vestiges of animals that inhabited the continent before the arrival of colonizers.
In these dogs, the pre-Columbian ancestry was estimated at about 4% in Chihuahuas and 3% in Xolos, but the exact origin of this heritage was unknown.
Although the new research did not solve the entire mystery, it confirmed that one of these ancestors is the wild coyote, a native animal of North America. It was found that several sections of the Chihuahua genetic material were also identified in coyotes.
It is not possible to determine exactly how or when the Chihuahua and coyote lineages crossed; this could have been a chance event or the result of deliberate breeding between the species. However, the main theory suggests that these genetic mixtures occurred with the Chihuahuas even before American colonization.
Additionally, the study does not specify which Chihuahua characteristics originate from coyotes. Regarding the size difference between the species, one hypothesis raised suggests that this may have been the result of human selection for smaller dogs throughout history.