This Little Piggy Stayed Home

By Pat van Hartesveldt

Reprinted with permission of the author and the publisher, the  Los Angeles Zoo Docent Newsletter, Summer 2008 

Pigs were probably first domesticated about 9,000 years ago, simultaneously in Turkey and in China, and all varieties of domestic pig today are likely descended from the Old World wild boar that still roams the forests of Europe.  In many ways domestication was a good fit for both pigs and humans; pigs seem to enjoy company, whether of other pigs or of humans; they are not territorial and are willing to move whenever and wherever humans do; pigs do not need to be herded, instead they’re able to explore the countryside, wandering happily when and where their fancy takes them; and they are easily trained to come when they are called (hence “hog calling”).

Like us, pigs are omnivores, and instead of being adapted to eat only low-quality vegetation, and thus forced to graze for up to 20 hours a day, pigs’ omnivory permits them to spend much less time eating.  They can digest more nutritious food when it’s available, doing so at selected times during the day, and they sleep all night, just as we do.

In his definitive book The Whole Hog, author Lyall Watson suggests that omnivory plays a substantial role in enhancing intellectual activity.  “Being omnivorous goes hand in hand…with being curious, dexterous, and willing to explore new ways of finding, preparing, and keeping food.  Omnivores never stop investigating and are always on the lookout for anything in the environment that can be bent to their advantage.  They are easy-going non-specialists, ready to adapt to changing times, and this shows in (pigs’) brains and behavior.”


Mention pigs to most of your friends and they’ll say something like “Oooh!  I LOVE pigs!  They’re very smart, you know.”  Well, yes, we all “know” pigs are smart, but there’s surprisingly little real science to prove it.  We’ve heard the anecdotal evidence of pig “intelligence”:  pigs that unlatch gates to go visit the pretty sow next door; pigs that tell time, do arithmetic and spell; performing pigs that are taught to dance, climb ladders and jump through hoops.

Not surprisingly, most scientific research on pigs is done on domestic pigs and on behalf of the agricultural industry (folks who cannot afford, either financially or emotionally, to care how smart a pig is), and has far less to do with pigs’ intelligence than with husbandry issues.  Thus far, the few cautious studies on pig cognition show that pigs are good problem solvers, have well-developed spatial memories, “can find and memorize patterns, benefit from them, and make appropriate adjustments each time the rules change.” 

             In maze tests administered to dogs, chickens, horses, sheep, cats and pigs, pigs come out on top every time.  There are tantalizing hints that the pig may even have a “theory of mind,” the ability to recognize that other animals think thoughts, and not necessarily like the pig’s own.

It is interesting to note that these few studies have been done only on domestic pigs.  The difference between domestic pigs, clever as they may be, and their wild counterparts is striking.  When the wild boar became the domestic pig, its brain became 20% smaller, its head shrank, its legs grew shorter, and its body lengthened – all new adaptations to a life no longer spent on the run from potential predators.  Their ears often became floppy, resulting in less acute hearing (in fact, floppy ears were deliberately selected by farmers, as floppy-eared pigs tend to be more docile).  Their coarse, long body hair, including bristles and manes, became finer and softer, and there was now a lot less of it.  Their tails curled.  Piglets of domestic sows were no longer striped.  The skull lost its adornments like tusks, the snout became shortened, teeth crowded the lower jaw, and the forehead steepened, giving domestic pigs a dished face.

Amazingly, when barnyard hogs become feral, all these domestic adaptations are quickly reversed; changes in the size and shape of the skull occur within a single generation as the pig brain starts to grow again.  The head becomes longer, the snout straighter and narrower.  The coat becomes denser; the hair grows more bristly, as does the pig’s attitude.  It seems that after all those millennia, the wild boar material still lurks in the genes of domestic pigs.

Porky, Piglet, Wilbur, Freddy and Napoleon are one unlocked gate away from becoming all that they can be.

Heaven help us.