Part I: Evolution, Taxonomy, and Domestication42
(relationship between size and shape). Differences between
breeds have also been shown based on their molar (Evin et al.
2015a) and cranial (Owen et al. 2014) shapes – likely the result
of distinct past and present husbandry practices and local envi-
ronmental factors.
Only one GMM study includes captive wild boar (Evin et al.
2015a). Because domestication often implies captivity, it is of
prime interest to attempt to untangle the effects of both domes-
tication and captivity in shaping phenotypes. These processes
are difficult to separate, especially due to the lack of adequate
modern specimens of known status on which detailed analysis
can be performed and because of the potential effects of inbreed-
ing that can of course also take place in captivity – and therefore
during domestication. Wild boar raised in captivity for at least
three generations show significant differences in molar shape
and size compared to their wild counterparts, suggesting that
the human-controlled environment has a strong influence on
the phenotype (Evin et al. 2015a).
Wild–domestic crosses have been studied for both their
molar (Evin et al. 2015a) and cranial (Owen et al. 2014) mor-
phologies. They possess molar shapes (specifically the M2)
strictly intermediate between the two parental forms – likely
the result of a cumulative effect of the two parental genomes.
However, analyses of third molar (Evin et al. 2015a) and cranialshape (Owen et al. 2014) revealed a greater similarity between
hybrids and wild boar. The size of the hybrids (that also lived
in captivity) is clearly closer to those of domestic pigs in the
molar analyses (Evin et al. 2015a) and overlapping with the two
parental forms for the crania (Owen et al. 2014), suggesting that,
potentially, both the environment and genotype are implied in
the smaller size observed in the captive specimens.
Only one GMM study has explored the geographic varia-
tion of wild boar (Evin et al. 2015a) and focusing only on the
West Palaearctic. Wild boar molar size, shape, and allometry
appeared to be strongly affected by geography, potentially the
result of different glacial refugia (Alexandri et al. 2012). Two
groups have been identified based on their molar shape –
especially the second molars (Evin et al. 2015a); a first compris-
ing Eastern populations from Russia and the Near East, and the
second including Western specimens from Europe and North
Africa. Regarding size, specimens from the East possessed
larger teeth than specimens from the West, complying with the
principles of Bergmann’s rule (Meiri & Dayan 2003).
Feral pigs have been analysed and discussed in Evin et al.
(2015a). However, because the specimens included in this study
both came from relatively large islands (Corsica and Sardinia),
their relative states of insularity and feralization – as shown by
their modern phenotypes – cannot be disentangled easily.Figure 4.3 Map of the geographic area covered by the geometric morphometric studies of pig domestication. In dark grey the modern distribution of wild boar.
Stars: two main centres of pig domestication. Numbers refer to the publications in Table 4.1..00612:31:36