Wild pigs of Southeast Asia

If you want to remember only two things from this episode, I’d give you these: Southeast Asia has eleven species of wild pigs, more than anywhere else in the world; African swine fever is circulating in the region and threatens many of these unique and endangered wild pigs.

I’m delighted to kick start Monsoon‘s Doing Science series with a show on wild pigs. These animals roam the swamps, beaches, forests, and hills from Myanmar to Sulawesi. And of the eleven found here, ten are endemic to the region. What better animal to lead a podcast that explores the science of Southeast Asia?

Pigs galore

Now, imagine a pig.

The pig which we have domesticated more than 9,000 years ago is Sus scrofa. This is the same species of the animal which we often call the ‘wild boar’ or ‘babi hutan’ in Borneo. The domesticated Sus scrofa lives inside pens; the wild ones live in the forests.

The other wild pig species though subscribe to a different fashion sense. While the wild boars are “stocky”, as Matthew Linkie describes them, the Bornean bearded pigs grow beards above their noses (females have some on their jaws) and have “elegant, lean bodies with long legs”.

Don’t picture a giraffe though. All pigs stay close to the ground. They are down-to-earth in that way and many others.

Then there the warty pigs, five species found across Java island and the Philippines. In these pigs, warts are sexy and safe. Males butt heads to win over females and facial warts could have evolved to cushion the blow. It’s a case where thick warts save you from the ward…I guess.

Swine richness

Of the 18 species of wild pigs worldwide, eleven live in Southeast Asia. What explains this diversity? Perhaps it’s the fragmented landscape of Southeast Asia, with the thousands of islands in the Philippines and Indonesia, says Matthew.

Islands, valleys, mountain ranges (all of which are abundant across Southeast Asia) can splinter a population of pigs (or any animal for that matter) into pockets (a process called ‘vicariance’). Separated and not able to breed with other groups (‘reproductive isolation’),  each pocket could change and adapt to its immediate environment.

As small changes pile up, a pocket could become so different that it eventually evolves into a new species that cannot breed with other populations, even if they meet again.

Some of the world’s oldest lineage of living pig species are found in Southeast Asia, says Sheherazade, who goes by ‘Shera’ for short. The babirusa (Babyrousa) of Sulawesi, for example, evolved more than 10 million years ago, even before the more cosmopolitan Sus genus. That makes babirusa the “oldest guy” in the pig family, Suidae, says Shera.

A key citizen

And in some communities, such as the Dayaks in Borneo, men hunt wild pigs not just for food, but also as a rite-of-passage, says Matthew.

Our forests must have harboured huge numbers of wild pigs, perhaps up to a few decades ago. Matthew recalls stories of “trains of thousands and thousands” of wild bearded pigs migrating across Borneo. The pigs were migrating across the land, tracking the fruiting season in the rainforest. Bearded pigs still migrate, of course, but I have only heard biologists describe them as “hundreds” now, not “thousands”.

Still, hundreds of bearded pigs sprinting through the palms and trees on their lean long legs, sniffing for the scent of ripe fruits – what a sight it must be!

Southeast Asians forests would likely be poorer without wild pigs. These animals, numerous and meaty, provide crucial nutrients to indigenous communities and many predators, some endangered like the Sumatran tiger and the Javan leopard.

And by gorging on fruits and defecating some distance away, the pigs could help trees disperse their seeds too. We often hear of hornbills or elephants described as ‘gardeners of the forests’ – wild pigs might be gardeners in that sense too.