Question

Passage A
For over half a century, zooarchaeologists investigating the origin of the domestic dog (*Canis lupus familiaris*) have relied primarily on physical osteological remains—specifically cranial dimensions, dentition reduction, and limb proportions—to distinguish early domestic dogs from wild gray wolves. The most robust and undisputed physical evidence comes from Upper Paleolithic burial sites across Western Eurasia, most notably the 14,000-year-old Bonn-Oberkassel specimen discovered in Germany. This canid was intentionally interred alongside human remains and exhibited a distinctly shortened snout, crowded premolars, and a reduced overall body stature—morphological markers traditionally defined by anatomical experts as the hallmarks of the "domestication syndrome."

Zooarchaeologists maintain that morphologically distinct dogs emerged only after prolonged, intensive cohabitation with human hunter-gatherer societies. According to this structural framework, dramatic physical alterations occurred synchronously with human-managed selective breeding and intentional cultural integration. Proponents of the zooarchaeological model emphasize that prior to approximately 15,000 years ago, canid bones recovered from Eurasian archaeological contexts show no statistically significant skeletal deviation from wild wolf populations of the Late Pleistocene. Consequently, researchers in this field argue that claims proposing a much earlier origin of domestication rely on isolated, damaged fossil fragments—such as the 33,000-year-old Goyet dog from Belgium—that merely represent natural morphological variation within ancient wild wolf populations rather than genuine domesticates. For zooarchaeologists, unambiguous physical evidence of anatomical alteration remains the essential diagnostic threshold for confirming true domestication.

Passage B
Recent advancements in paleogenomics have fundamentally reshaped the scientific debate surrounding canine domestication by analyzing whole-genome sequences extracted from ancient canid fossils across Eurasia. Evolutionary geneticists utilizing molecular clock models, population bottleneck analyses, and comparative genomic sequencing contend that the genetic divergence between ancestral dogs and gray wolves occurred between 20,000 and 40,000 years ago, long before the appearance of unambiguous skeletal changes in the archaeological record.

According to paleogenomic research, the initial stages of domestication were likely driven by a gradual process of "self-domestication." Scavenging wolf populations possessing lower flight distances began exploiting leftover animal carcasses near human hunter-gatherer encampments. During this extended transitional phase, natural selection targeted physiological pathways regulating adrenaline production, stress responses, and social tolerance. Geneticists argue that selective pressure on behavioral and metabolic traits leaves a distinct signature in the genome while leaving macroscopic skeletal structures virtually unchanged for thousands of generations. As a result, paleogenomicists maintain that relying strictly on osteological markers severely underestimates the true antiquity of the human-canid partnership. From a genetic perspective, the absence of altered skull morphology in 30,000-year-old specimens does not disprove domestication; rather, it demonstrates that behavioral and genetic divergence systematically precedes structural anatomical adaptation.

Passage A and Passage B both address the scientific debate surrounding the timeline of canine domestication. Which of the following best describes how the authors of Passage A and Passage B evaluate the significance of 30,000-year-old canid fossils lacking modified skull shapes?