Part I: Evolution, Taxonomy, and Domestication6
C. wagneri. In summary, the phylogenetic relationships among
the three extant peccaries from DNA and some morphological
data are consistent (Theimer & Keim 1998; Gongora & Moran
2005; Gasparini et al. 2013), but other morphological analyses
differ from this conclusion.Taxonomy of Suidae and Tayassuidae
Taxonomic Background: What Is a Species
and a Genus?
A species is an evolutionary lineage (De Queiroz 2007).
Subsequent to the individuation of a lineage, a number of defining
characteristics is likely to accrue at different times: diagnosability,
ecological niche specialization, specific mate recognition
systems, intersterility vis-à-vis sister species, increasing genetic
divergence, and so on. The earliest of these characteristics is
likely to be diagnosability. Accordingly, a species may be defined
as ‘the smallest population or aggregation of populations which
has fixed heritable differences from other such populations or
aggregations’ (Groves & Grubb 2011: 1). This is the Phylogenetic
Species Concept (or better, the phylogenetic criterion of the
Evolutionary Species). Note that this is a fail-safe criterion: once
100 per cent of individuals of one lineage have come to differ from
all individuals in other lineages, the lineage has been irrevocably
launched onto a separate evolutionary path. In the terminology
of Ghiselin (1974), it has become an individual.
The phylogenetic criterion frees us from subjective judge-
ments of ‘how much difference is necessary’, and from spurious
quandaries of what to do if hybrids are discovered. A phyloge-
netic species is testable (falsifiable in the Popperian sense).
In the Suoidea, it is often difficult to decide whether a par-
ticular OTU (operational taxonomic unit) is a genuine species.
This is because the evidence of diagnosability may be poor; on
the available evidence, a given OTU may be 100 per cent distin-
guishable, but further research may alter this. We list such cases
here as unconfirmed candidate species.
Within a species, it is sometimes the case that different geo-
graphic segments differ noticeably on average, for example by
high frequencies of particular genes. These may be designated
subspecies; but this concept has been overused in the past to
encompass anything from slight average differences between
geographic populations to cases of distinct species that, although
clearly individuated, are not strongly so. Subspecies are a subjec-
tive concept and cannot be reified in the same way as species.
As argued by Groves and Grubb (2011: 4), a genus (in the
modern fauna) is a monophyletic group of species (sometimes
a single species) that has been separate from other such groups
since the Miocene–Pliocene boundary, i.e. approximately
5 Ma. This definition is an attempt to render objective a category
which has traditionally been simply a matter of opinion – surely
not a basis for scientific argument!Suidae
The outstanding apomorphic character state of the family
Suidae concerns the males’ canines. In most mammals, the max-
illary canines project directly downward, and the mandibularones project directly upward and occlude slightly in front of the
maxillary ones. In all Suidae, except for the genus Babyrousa,
the males’ maxillary canine, more or less ovoid in cross-section,
forms a close spiral, emerging downward and outward from
the alveolus, then curving strongly outward and upward and,
except when extremely worn, slightly inward again. The man-
dibular canine, much more triangular in cross-section, emerges
from its alveolus mainly upward and outward and with a slight
forward inclination, such that one of its faces occludes against,
and is sharpened by, the inferior surface of the maxillary canine.
The result is a vicious weapon protruding laterally, the lower
canine constantly kept sharp against the upper by chomping
movements of the jaws; the upper canine helps to protect the
face during combat. The canines of females are more like those
of ‘normal’ mammals, but more laterally directed; they are
very short.
The canines of Babyrousa are different from this system,
although evidently derived from it. The alveolus of the maxil-
lary canine appears to rapidly rotate upward during the juvenile
period, and the canine grows through the skin, mainly upward,
curving back so that its tip points downward or even slightly for-
ward. The mandibular canine grows upward and becomes very
long, acting as a stabbing weapon; the maxillary canine evidently
protects the eyes during combat. The female lacks canines.Babyrousa Perry, 1811
The babirusa (literally, pig-deer). As well as the bizarre canine
system of the male, this genus is characterized by the form of
the stomach. They are long-legged, relatively lightly built pigs
restricted to Sulawesi and offshore islands, and the Sula Islands
and Buru to which they have been introduced. It has been pro-
posed that Babyrousa consists of three species (B. babyrussa,
B. celebensis, B. togeanensis) (Meijaard & Groves 2002), well-
differentiated on both craniodental and external characters;
genetic studies purported to refute this taxonomic arrangement
remain unpublished. The three species listed below are based
on differences in external morphology, cranial morphology and
shape of canines (Meijaard & Groves 2002).
Babyrousa babyrussa (Linnaeus, 1758). Buru and two of the
Sula Islands; it has probably been introduced to all these islands,
perhaps by the Bugis from the southern peninsula of Sulawesi,
where babirusas are now extinct (species name B. bolabatuen-
sis). Animals very similar to the Buru/Sula ones still exist in the
centre of Sulawesi, but their exact distribution there is unclear
(see below). Body size is small and cheekteeth are small. The
male’s upper canine is short and slender; the alveolus is for-
wardly rotated, so that the upper and lower canines cross in side
view. Externally, the body hair is long and thick, and there is a
well-developed tail tuft.
Babyrousa togeanensis Sody, 1948. Malenge, in the Togean
Islands. Much larger than B. babyrussa, but like the latter
the cheekteeth are small and the male’s upper canine is short.
The body hair is somewhat less thick, and pale on the underside.
Babyrousa celebensis Deninger, 1909. Northern peninsula
of Sulawesi. Large in size, with large cheekteeth and long, thick
upper canines, which are more vertically implanted so that
upper and lower canines do not cross in lateral view. The body.00312:27:47