Size and shape of the semicircular canal of the inner ear: A new marker of pig domestication?

Abstract

Domestication has led to many changes in domestic animal biology, including their anatomy. The shape of the inner ear, part of the mammalian ear, has been found particularly relevant for discriminating domesticated species, their hybrids or differentiating the wild and domestic populations of a single species. Here we assessed the use of the size and shape of the semicircular canals (SCC) of the inner ear as a marker of pig domestication. We studied a total of 63 petrosal bones belonging to wild boar (Sus scrofa, two populations) and domestic pigs (extensively and intensively reared specimens) that were µCT‐scanned and from which the size and the shape of the inner ear were quantified through geometric morphometrics, analyzing the 3D coordinates of 6 landmarks and 60 sliding semilandmarks localized on the SCC and the common crus. The domestic pigs have larger SCC than the wild boar from which they also strongly differ in shape (correct cross validation of 95.5%, confidence interval: 92.3%–98.1%). Strong shape differences were detected between the two populations of wild boar, as well as a sexual size dimorphism. All together the results highlight the taxonomic discriminant power of the SCC of the inner ear shape, and its relevance for domestication studies.

New fossils from Kromdraai and Drimolen, South Africa, and their distinctiveness among Paranthropus robustus

“…This is the case for one P. robustus (SK 83) and two A. africanus (Taung child, MLD 31) specimens. As demonstrated both previously 4 and in the present study, there are no differences in BL size and shape between adult and juvenile specimens among hominid species, and in other placental mammals 39 , 51 . We therefore combine juvenile and adult specimens in our samples.…”

“…Variation in BL morphology related to allometry is ubiquitous among primates 35 but has not yet been investigated in A. africanus and P. robustus . We therefore newly add evolutionary allometry to approaches of BL that already proved their utility to reveal species-specific characters among primates 13 , 36 , 37 and other mammals 38 , 39 , and differences between A. africanus and P. robustus that exceed those between modern humans, chimpanzees and gorillas 4 .…”

Ruminant inner ear shape records 35 million years of neutral evolution

“…Neutral evolutionary processes seem to be driving its morphological evolution, visible at the microevolutionary level. This demonstrates that fine scale bony labyrinth shape differences in populations of closely related species are significant 22,54 . Our contrasting results on evolutionary rate shifts in various groups show striking similarities to molecular evolutionary rates.…”

Archaeophenomics of ancient domestic plants and animals using geometric morphometrics : a review

“…Late Glacial horse (Bignon et al, 2005), rabbit (Pelletier, 2019)); and finally the numerous studies focusing only on modern domestic specimens (e.g. Battesti et al, 2018;Bonhomme et al, 2017;Evin et al, 2022;Gros-Balthazard et al, 2016;Hanot et al, 2021;Harbers et al, 2020;Neaux et al, 2020;Pelletier, Kotiaho, Niinimäki, & Salmi, 2020, 2021. Yet these studies are of prime interest for the understanding of ancient populations, they fall out of the scope of this review.…”