Unexpected morphological diversity in ancient dogs compared to modern relatives

Abstract

Dogs are among the most variable species today, but little is known about the morphological variability in the early phases of their history. The Neolithic transition to farming may have resulted in an early morphological diversification as a result of changes in the anthropic environment or intentional selection on specific morphologies. Here, we describe the variability and modularity in mandible form by comparing 525 dog mandibles from European archaeological sites ranging from 8100 to 3000 cal. BC to a reference sample of modern dogs, wolves, and dingoes. We use three-dimensional geometric morphometrics to quantify the form of complete and fragmented mandibles. We demonstrate that an important morphological variability already existed before the Bronze Age in Europe, yet the largest, smallest, most brachycephalic or dolichocephalic extant dogs have no equivalent in the archaeological sample, resulting in a lower variation compared to modern relatives. The covariation between the anterior and posterior parts of the mandible is lower in archaeological dogs, suggesting a low degree of intentional human selection in early periods. The mandible of modern and ancient dogs differs in functionally important areas, possibly reflecting differences in diet, competition, or the implication of ancient dogs in hunting or defence.

ZooMS confirms geometric morphometrics species identification of ancient sheep and goat

“…Modern specimens are often the only available reference of securely identified species, however, it has been demonstrated that modern references can lead to misidentifications. For example, modern dog breeds are not a good proxy to identify archaeological specimens [93]. This is also the case for other domestic species for which it is well known that direct selection over the last two centuries was intensified, followed by standardization of morphology and performance with the emergence of the breed concept [94][95][96][97].…”

Self-Domestication: From Analogy to Homology via Genomics

“…Could this be the underlying reason why dogs display the fullest number of traits falling under the domestication syndrome in 42 ? In addition, we must bear in mind that the extended period of sociality induced by selective breeding carries with it its own anatomical consequences 46,47 that may in part obscure the impact of the earliest stages of domestication and the presence of the 'domestication syndrome' in its most pristine form, as it were. This point is made particularly clearly in 48 , whose comprehensive phylogenetic analysis of the effect of sociality, insularity, and domestication on brain size demonstrates the robust relationship between domestication and brain size reduction (contra 39 ), but also highlights the confounding effect of extended sociality (often associated with brain size increase).…”

4500 years of morphological diversification in Western Europe wild boars (Sus scrofa) and the consequences of the Neolithic transition

“…With the emergence of agriculture and, more generally speaking, the Neolithic transition, the human niche construction caused a major ecological disturbance, with the opening and fragmentation of the landscape, the emergence and spread of domesticated animals and plants from several independent centres across Eurasia, the protection of livestock from predators and competitors, and the dispersal of invasive species and pathogens (Ellis et al, 2021;Sullivan et al, 2017). To date, the influence of the Neolithic niche construction has been mainly explored through human-induced species distribution (Boivin et al, 2016;Cucchi et al, 2020;Vigne, 1999), and over the temporal depth of the direct human influence over species during the process of animal domestication (Ameen et al, 2019;Brassard et al, 2022;Clutton-Brock, 1992;Cucchi et al, 2021;Fages et al, 2019;Frantz et al, 2020;Larson and Fuller, 2014;Zeder, 2015). Yet, its consequences on non-domestic species evolution remain to be fully documented and understood (Erlandson et al, 2016;Sarrazin and Lecomte, 2016).…”