Not the Pig Family: Fossil Peccaries and More

Mylohyus

Today, there are only three recognised living species of peccary, the smallish pig-like animals that inhabit the Americas... and one of those is endangered. However, these are but the last remnants of a once much larger group with a fossil history that stretches back even further than that of the true pigs.

While pigs date back, at the best, to the end of the Oligocene epoch, the oldest known peccary fossil dates from the end of the epoch before that, the Eocene. This implies that the ancestors of the peccaries entered North America from Asia between 36 and 34 million years ago. The fossil in question belongs to a species known as Perchoerus minor, and it's also worth noting that it is also the smallest peccary known... in fact, it was about the size of a typical house cat.

The Pig Family: Fossil Pigs

Kubanochoerus, the unicorn-pig

There are seventeen widely accepted species of pig alive today. Although some, notably the wild boar and the two kinds of warthog, are doing absolutely fine in the grand scheme of things, many are threatened to varying extents by hunting and loss of habitat. Three - the pygmy hog and the Visayan and Javan warty pigs - are formally listed as endangered species by the IUCN, and many of the others are just outside that category. On the bright side, no clearly identified species of pig has actually slipped over the line into extinction in the last few thousand years. But, of course, if you go back a few million years, it's a rather different story.

Indeed, in some respects, the pig family as it exists today is a shadow of its former self. Pigs have always been reasonably successful animals (at least, without human interference), given their adaptability, moderate intelligence, and willingness to eat just about anything. But, in the past, they were more varied than today. In total, there are five generally recognised subfamilies within the overarching pig family - and all but one of them are known only from fossils.

Not the Pig Family: Peccaries of the World

Collared peccary

I've already described the anatomical and biological differences which mean that, despite appearances to the contrary, peccaries are not pigs. I've also described all the various living species of the pig family, which means that it's now time to do the same for the living species of the peccary family.

The peccary family is, however, a lot smaller than the pig family: it contains just three living species.

The one that's likely most familiar to readers of this blog is also the most widespread: the collared peccary (Pecari tajacu). It's so-named because of the thin 'collar' of whitish hair that runs from its shoulders across the throat, although, in practice, this isn't always as visible as it might be. The animal is found through pretty much the whole of central and northern South America east of the Andes, through most of Central America, coastal (but not central) regions of Mexico, and into neighbouring parts of the USA, where it can be seen in Arizona, New Mexico, and Texas. If a distinction is needed, this is the true "javelina", since it's the one that's common where that alternative word for "peccary" is most commonly used.

The Pig Family: Peccaries Are Not Pigs

Over the the year so far, this series has described every living species of pig. Yet there are some animals that might seem to be missing. Found across much of Latin America, and up into the southwestern USA, we can find animals known as peccaries. These certainly look like pigs, and, unlike razorbacks, which can also be found in the US, they are genuinely wild animals, not the descendants of domesticated ones that happen to have escaped.

The reason I haven't mentioned them so far is, as the title of the post makes apparent, that they aren't actually pigs. So why the heck not, and what are they, if they're not pigs?

The Pig Family: The Strange Case of the Sulawesi Pig-Deer

Sulawesi babirusa

Warthogs are fairly odd-looking animals, as are forest hogs, among others. But, at least to my mind, when it comes to wild pigs, nothing quite beats the babirusas.

These strange looking pigs inhabit the island of Sulawesi in Indonesia. Unlike most of the others in the group, this has been an island for far longer than pigs have been in existence - when sea levels were lower, most islands to the west were joined with Asia, and those to the east with Australia, but the waters around Sulawesi are so deep that it remained isolated. I've mentioned this before, in the context of warty pigs, so it's interesting to note that those channels must have been crossed by wild pigs on no less than three occasions (the third sort of Sulawesian pig, Celebochoerus, died out in the Ice Ages).

The Pig Family: Warthogs

Common warthog

Warthogs are, quite possibly, the best known species of wild pig after the wild boar itself. They are relatively common animals, readily observed in the habitats where they live (rather than hiding in dense thickets, say) and, perhaps above all, they have a striking and distinctive appearance.

The common warthog (Phacochoerus africanus) is widespread across sub-Saharan Africa, and is currently thought to have four different subspecies. Unlike other African hogs, they inhabit lush grasslands and open savanna, country dotted with trees and waterways, but neither densely forested nor the truly arid terrain of veldt or desert. Two subspecies live in the north, in the Sahel belt that separates the Congo rainforest from the Sahara, and are found right from the Atlantic coast of Mauritania to the shores of the Red Sea in Eritrea. The others are found across East Africa and pretty much the entire south of the continent outside the deserts, reaching as far as South Africa.

The Pig Family: Bush Pig, Bushpig, Red River Hog

Red river hog (boar)

As zoological knowledge has advanced, the number of species that we know about has changed regularly, and not just because we keep discovering new ones. Animals that we knew about, but previously thought were subspecies get promoted to full species, and animals that we thought were separate species turn out not to be.

In fact, over time, we can sense something of a trend here. Beginning with Linnaeus in 1758, several new species are named, often by naturalists unaware, in the days before fully up-to-date reference libraries, let alone the internet, that somebody else had already given a name to the same thing. That process continues through the 19th century, with minor differences being seized on as evidence of speciation, even where it was possible to make decent comparisons. Through the 20th century, the number of genuinely new species being discovered dramatically tails off (at least, for mammals), but there's also a tendency to tidy up the great mass of inherited names from the past, merging similar animals together. Finally, from the late 20th century onwards, an increasing understanding of genetics results in numerous subspecies being promoted, often with our Victorian predecessors turning out to have been right all along.

The Pig Family: The World's Largest and Smallest Pigs

Pygmy hog

By some definitions, the term "pig" can really only be applied to those species that are most closely related to the domestic animal; those included within the genus Sus. This includes the wild boar, and the various kinds of warty and bearded pig that inhabit the Indonesian and Philippine islands.

But these are not the only pig-like animals to inhabit Asia. In 1847, Brian Hodgson, a naturalist and former colonial administrator who was living in Darjeeling at the time, described and named the pygmy hog (Porcula salvania), an animal he considered so different from regular pigs in the shape of its teeth and feet that he placed it in its own, newly defined, genus, Porcula. (The scientific name, incidentally, translates as "piglet from the Sal Van", the latter being a forest that only coincidentally sounds like the Latin "silvae" meaning "woodland").

The Pig Family: Threatened Pigs of the Philippines

Visayan warty pig (female)

When the animal we now know as the Sulawesi warty pig was first described, back in the 19th century, it was thought that it lived, not only on the island of Sulawesi, but also on a whole chain of islands to the north - the Philippines. But the pigs there didn't look exactly the same as those to the south, so in 1886, German zoologist Alfred Nehring proposed that they be regarded as a distinct subspecies.

And so things remained for a hundred years, until scientists began to look more closely at the animal's genetics. When they did so, they discovered something fairly surprising. Pigs typically have 38 chromosomes (compared with 48 in humans), but it turned out that the warty pigs from the Philippines had only 36 - an entire pair had disappeared, its genetic material shuffled around elsewhere in the genome.

The Pig Family: Wild Pigs of Indonesia

Bearded pig

Thanks to their adaptability, wild boar are a remarkably widespread species, being found from Portugal to Japan. All of their close living relatives, however, are much more restricted, each being isolated on different islands or island chains off the south-east coast of Asia.

The largest such island, and, indeed, the third largest island in the world, is Borneo. This is home to the bearded pig (Sus barbatus), which is also found, not only on the neighbouring island of Sumatra, but also on the Malaysian mainland. The Bornean and Sumatran forms of the animal are widely regarded as different subspecies - the latter going by the rather brilliant name of S. b. oi - although quite which of these two the Malaysian pigs belong to has been a matter of mild controversy.

The Pig Family: Wild Boar and the Domestication of Pigs

European wild boar

Generally speaking, the wild ancestors of agricultural animals have not fared particularly well. Wild goats are a threatened species, wild horses are an endangered one, camels are doing even worse, and wild cattle have been extinct for centuries. Wild sheep haven't done quite so badly, although they're hardly widespread, but, in general, one of the main problems facing such animals is that the sort of places they like to live are exactly the ones we want to turn into agricultural land to raise their domesticated kin.

Indeed, only two wild ancestors of widely domesticated herbivore are doing well: chickens and pigs. (This may, of course, depend on your definition of "widely"; I'm ignoring, say, rabbits). Indeed, the wild ancestor of the domestic pig is not only reasonably common, it's the single most widespread of any species of wild pig.

The Pig Family: Suids, Suines, and Swine

The pigs occupy an an interesting position in the mammalian family tree. The pig family, or Suidae, belongs to the order Artiodactyla, consisting of the cloven-footed mammals and a few of their closest relatives. (I will, at this point, note that I'm going to be using "artiodactyl" in the traditional, non-molecular sense, in this post. Paraphyly be damned, at least for today.)

This is unsurprising, given that pigs do, indeed, have cloven hooves. However, there are other features that almost all artiodactyls have in common, most significantly, that they are purely herbivorous animals with multi-chambered stomachs that they use to "chew the cud". Pigs, however, do not, and while they may not be the only non-ruminating artiodactyls, they are by far the most species-rich group to fit this description.

Traditionally, this was thought to be because they are more "primitive", having evolved before their relatives got round to developing more complex digestive systems. In a more modern way of looking at things, we'd instead note that, compared with other artiodactyls, pigs are omnivorous; they haven't developed more efficient ways of digesting tough plant matter because they don't need to. That they've survived as well as they have, evolving over many millions of years without ever being wiped out, shows that this has been a pretty successful tactic for them.