We’re all familiar with the idea that widespread mammal species (virtually always) consist of a whole bunch of populations that we term ‘subspecies’. And I must have said – flashback here to articles about sheep – that one of my perpetual frustrations is that it’s often quite hard to find good information on various of the subspecies that (for cultural or geographical reasons) are ‘obscure’. And this is all the more frustrating when some of these ‘obscure’ subspecies are really neat in appearance, often being weirder or more spectacular than the subspecies we’re more familiar with.

Indian wild pig with erect dorsal crest. Photo by JP Bennett, CC BY 2.0.

Enough preamble. The reason we’re going down this route is because I want to talk about a form of Wild boar Sus scrofa that doesn’t get a tremendous amount of attention. Namely, the Indian boar, Indian wild pig, Andamanese pig or Moupin pig S. s. cristatus of India, Sri Lanka, Nepal, Thailand and Myanmar, a very dark, lightly built, thinly furred wild pig named for its striking dorsal crest formed of long, erectile bristles. It also has especially long bristles on the cheeks and the rear part of the lower jaw, giving it a sometimes prominent beard.

Check out the mane and beard on this animal. Photo by Bernard Dupont, CC BY-SA 2.0.

The Indian wild pig looks about ‘different enough’ from other wild pigs that it was originally (in 1839) described as a distinct species – S. cristatus. The idea that it should be regarded as such was popular until the 1970s at least. It was in that decade that a bunch of taxa previously regarded as distinct wild pig species (namely S. meridionalis of Corsica and Sardinia, S. leucomystax of Japan, S. riukiuanus of the Ryukyu Islands and S. vittatus of far eastern Asia) were sunk into S. scrofa and downgraded to subspecies status.

Those of you who keep up with the world of mammal taxonomy will no doubt being thinking of the three words ‘Groves and Grubb’ at this point. Yup, Groves & Grubb (2011) propose that a long list of Sus taxa should be re-elevated to species status, S. cristatus among them. While I think that many of their suggestions do have merit, I also agree with those who say that taxonomy works on consensus and I’m not convinced that we gain much by following this proposal.

Many Indian wild pigs are sparsely furred, though note that the dorsal mane is still evident here. Photo by Steve Garvie, CC BY-SA 2.0.

I should also say that there are a number of alleged Asian wild pig populations – also originally described as species and then downgraded to subspecies – that somewhat intergrade into S. s. cristatus and it isn’t fully understood how they actually relate to one another.

Look at the great photos here to get some idea of how neat and impressive these wild pig can look. I say can look, because they don’t look especially impressive all the time – when the dorsal bristles are non-erect and the animals are in scrawny condition, they maybe don’t look so great.

Erect-crested individual photographed in the wild. Photo by Bernard Dupont, CC BY-SA 2.0.

S. s. cristatus isn’t just unusual on the basis of that dorsal mane. Unlike European wild boar, it lacks underfur (or underwool). It’s also an especially tall and tall-skulled wild pig, the dorsal margin of its skull being flat rather than concave, and its teeth are proportionally small and its nasal bones are short (Groves 1981). It lacks the facial bands present on some other Asian wild pig taxa.

Bipedal fighting behaviour is well known for babirusas. This screengrab is from the BBC series Life of Mammals.

There’s little information on the ecology and social behaviour of the Indian wild pig. It typically travels in bands and seems to be socially similar to better-known wild pig populations. Having said that, fighting behaviour in these animals was described by Barrette (1986) who observed Sri Lankan individuals (of various ages and both sexes) engaging in bipedal ‘wrestling’ behaviour. They stood for as long as a minute (though usually only for seconds at a time), rapidly stepping in order to maintain balance while flailing their forelimbs, jerking and throwing their heads and frothing at the mouth. Bipedal fighting behaviour is well documented for babirusas – distant relatives of Sus species within Suidae (and covered at length in a long series of old Tet Zoo articles: see the links below) – but is not considered a typical combat strategy of Sus species. I don’t know how widespread it is within the group.

Indian wild pigs have to deal with several predators that their relatives in Europe do not, most obviously tigers. Photo by Bharat Goel, CC BY 2.0.

The Indian wild pig is protected by law, but despite this it’s sometimes killed and its meat sold illegally anyway. There has been some effort to identify those parts of the genome that allow DNA from this wild pig to be distinguished from that of domestic pigs and hence to identify its remains found in markets (Gupta et al. 2013, Jadav et al. 2014, Srivastava et al. 2015), though I don’t know how successful or widely implemented these discoveries have been.

If you’re wondering whether the Indian wild pig might have contributed to the domestic pig gene pool, the answer is that it apparently has not (Jadav et al. 2014). In fact, genetic studies seem to show that S. s. cristatus is really quite distinct relative not only to domestic pigs but to all other Asian wild pig sampled so far – an intriguing discovery which might mean that it’s been influenced by an unusual period of isolation or that it has an unusual biogeographical history that we don’t yet have a handle on.

One final piece of esoteric trivia. I first learnt of this interesting beast thanks to Charles F. Tunnicliffe’s paintings in the following work, one of my favourite childhood books…

There are now quite a few Tet Zoo articles on the pigs of the world (wild and domestic). See...

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Barrette, C. 1986. Fighting behaviour of wild Sus scrofa. Journal of Mammalogy 67, 177-179.

Groves, C. 1981. Ancestors for the Pigs: Taxonomy and Phylogeny of the Genus Sus. Technical Bulletin 3, Department of Prehistory, Research School of Pacific Studies, Australian National University.

Groves, C. & Grubb, P. 2011. Ungulate Taxonomy. The John Hopkins University Press, Baltimore.

Gupta, S. K., Kumar, A., Hussain, S. A., Vipin & Singh, L. 2013. Cytochrome b based genetic differentiation of Indian wild pig (Sus scrofa cristatus) and domestic pig (Sus scrofa domestica) and its use in wildlife forensics. Science and Justice 53, 220-222.

Jadav, K., Rajput, N., Shrivastav, A. B., Mandal, S. & Shrivastav, G. 2014. Application of 12S rRNA gene sequence for identification of Indian wild pig (Sus scrofa cristatus). Journal of Meat Science and Technology 2, 79-84.

Srivastava, G. K., Rajput, N., Jadav, K. K., Shrivastav, A. B. & Joshi, H. R. 2015. Single nucleotide markers of D-loop for identification of Indian wild pig (Sus scrofa cristatus). Veterinary World 8, 532-536.