there really only one way—the human way—to experience feelings intensely and perhaps consciously? Evolution is not the single-track process we sometimes think (or maybe hope) it is. And birds, some of which possess diminutive brains, are a prime example that there is more than one route to intelligence. Since the age of their ancestors, the dinosaurs, their development has followed a different path from ours. Even without a neocortex, they can perform mental feats of the highest order. In birds, a region called the dorsal ventricular ridge oversees similar tasks and functions as our cerebral cortex. In contrast to the human neocortex, which is built up of layers, the equivalent area in the bird brain is made up of small clumps, a fact that fed long-standing doubt that it could perform a similar function.15 Today we know that ravens and other species that live in social groups can match, and in some cases even exceed, the mental prowess of primates. This is further proof of science’s practice of arguing too cautiously when in doubt about feelings in animals, denying them many mental capacities until there is positive proof that they possess them. Instead, couldn’t we simply (and just as accurately) say: “We don’t know”?
Before I end this chapter, I would like to introduce you to one more creature in our woods, an organism that is mindless in the truest sense of the word. Sometimes you can find it on rotting wood, where it forms a small, bumpy, yellow mat. It’s a fungus. Hold on a moment. Isn’t this a book about animals? Well, in the case of this fungus, science is not exactly sure which category it belongs to. It’s difficult enough with normal fungi, which form a third kingdom of living things in between animals and plants, because they cannot be clearly assigned to either category. Like animals, fungi subsist on organic substances from other living beings. In addition, their cell walls are made of chitin, like the exoskeletons of insects. And the slime mold that creates that yellow mat on dead wood can even move. At night, like gelatinous jellyfish, these organisms are capable of slithering out of the glass lab containers where they are temporarily confined. Today, science is moving them out of the realm of fungi and edging them a step closer to animals. Welcome to this book.
Researchers find some kinds of slime molds so interesting that they regularly observe them in the laboratory. Physarum polycephalum, with its somewhat awkward Latin name, is just such a customer, and it loves rolled oats. Basically, the creature is one giant cell with countless nuclei. What researchers are now doing is placing these slimy unicellular organisms in a maze with two exits and putting food at one of the exits as a reward. The slime mold spreads out into the maze and after a hundred hours or more, finds the exit with the oats—not bad, really. To do this, it clearly uses its own slime trail to recognize where it has already been. It then avoids those areas because they have not led to success. In nature, such behavior is of practical benefit, because the creature knows where it has already been in its search for food and, therefore, the places where there isn’t any food left. It’s quite a feat to be able to solve a maze when you don’t have a brain, and researchers credit these moving mat-like creatures with having some kind of spatial memory.16 Japanese researchers topped it all off by using a slime mold to reproduce a map of the most important transportation routes in Tokyo. To do this, they set a slime mold down on a damp surface at a point that represented the center of the city. Piles of food marked the principal neighborhoods as attractive places to visit. The slime mold set off, and when it had connected the neighborhoods using the optimal, shortest route, there was a big surprise. The image pretty much corresponded to the suburban train system in the metropolis.17
I particularly like the slime mold example, because it shows how little it takes to overturn our preconceptions about primitive Nature and stupid, emotionless animals. These alien creatures lack any of the basics laid out in the preceding chapters, and yet, if organisms with only a single cell have spatial memory and can perform complex tasks, how many undreamt-of skills and emotions might there be in animals with as few as 250,000 brain cells, like the fruit flies I’ve just introduced you to? Given how much more like us birds and mammals are in the physical structure of their bodies and brains, it would hardly come as a surprise if we were to discover that they are as sensitive to the world as we are.
5
PIG SMARTS
DOMESTIC PIGS ARE descended from wild boar, which were prized by our ancestors as a source of meat. About ten thousand years ago, wild boar were tamed to ensure the delicious animals were available at short notice without us having to go out on dangerous hunts to get them, and they were then bred to better satisfy our requirements. Despite this interference, modern domestic pigs have retained wild boar’s behavioral repertoire and, above all, their intelligence.
First, let’s look at how wild boar behave. (Feral hogs or swine in the US are descended from pigs that escaped domesticity and share behaviors with European wild boar.)18 For example, wild boar know exactly which other boar they are related to, even if the connection is a distant one. Researchers from Dresden University of Technology determined this indirectly when they were investigating the home ranges of family groups (known as sounders). As part of this research, 152 wild boar were caught in traps or stunned with tranquilizer guns, fitted with transmitters, and then set free again so the researchers could see where these nocturnal roamers hung out. The researchers discovered that there is normally not much overlap between neighboring sounder territories, and, on average, territories range from 1½ to 2 square miles in size, which is much smaller than previously thought.19
Wild boar rub against trees to mark their territorial boundaries. After wallowing in mud, they cover these “rubbing trees” with their scent. Scent markings, however, are not permanent, which means that boundaries between territories remain somewhat fluid, and so it’s little wonder that every once in a while, boar intrude where they don’t belong. As meeting up with strangers usually leads to altercations that even boar prefer to avoid, border violations by unrelated sounders are fairly rare, but if the home ranges of two related groups are side by side, their territories may overlap by as much as 50 percent. Clearly, wild boar are more kindly disposed to family members than they are to strangers and, most importantly, they can obviously tell the difference.
Family dispersal starts when the previous year’s piglets, the yearlings, are driven off as the birth of the next litter approaches. The sow has no extra time to look after older piglets, which are pretty independent by then. Wild boar are highly social and love to engage in mutual grooming or simply to lie snuggled closely together, and the siblings join up to form yearling sounders so they can continue living in a group. If the yearling sounders run into their extended families with their new piglets later in the year, the meeting will be a friendly one. Everyone knows everyone else and they all still get along well.
Thinking about our domestic animals, I’ve often wondered whether our goats and rabbits are capable of picking their grown-up children out of the group and recognizing them as relations. After observing them for a long time, I believe I can now answer this question with a resounding yes. With one proviso: that the animals are not separated from one another. If they are kept in separate enclosures for more than a few days, they end up treating each other as strangers. Perhaps their long-term memory is not configured for storing information about family relationships. It is clearly different for wild boar, and therefore also probably for domestic pigs, because they have long memories for who belongs to whom. This is of little use to domestic pigs, of course, because unfortunately for them, they are separated from their parents and raised in groups of other pigs their own age, and as a rule, they don’t make it past their first year.
These days, most people are aware that pigs are extremely clean animals. They prefer to use some kind of a toilet—a designated place where they do their business—be it big or small. This toilet is never in their sleeping hollow. After all, who would want to sleep in a stinky bed? This goes for both wild and domestic pigs. When you see photographs of tiny stalls in factory farm barns (11 square feet per animal) and pigs covered in muck, you can imagine how uncomfortable the animals must be. In the wild, boar adapt their sleeping quarters according to the weather and time of year. Because they select their
