It seems obvious to us that we can address each other by name when we communicate. In large societies, each person we want to single out has a personal name we can use when we want to get their attention. Whether we’re using email, an online app, or the phone, or having a face-to-face conversation, without this direct form of address we’d be lost.

We’re conscious of how important this is when we meet someone we’ve been introduced to before and we forget their name. Is naming a particularly human habit or is there something similar in the animal realm? After all, all social creatures face the same issue.

In mammals, there is a simple form of naming between mother and child. The mother utters a call using her normal voice. The child recognizes the call and responds with a clear vocalization of its own. But is this really an exchange of names or is this merely voice recognition? The argument in favour of the latter interpretation is that these special mother-child “names” seem to fade with time. Once the young animals are grown up and weaned, their mother no longer responds to them. What meaning does a name you’ve given yourself have when no one reacts to it? Does a temporarily meaningful call deserve to be called a name?

Even if we disallow such calls, science has discovered some instances of genuine personal naming in the animal kingdom. It’s no coincidence that this naming happens, once again, with ravens. Their close societal bonds provide an ideal background for answering questions about naming, because ravens cultivate lifelong relationships, not only between parents and children, but also among friends.

Naming calls are the way to go if you want to communicate over long distances and identify which individual is doing the talking. These inky black birds can master more than 80 different calls, a raven vocabulary if you will. Amongst these is a personal identification call a raven uses to announce its presence to other ravens.

But is this call really a name? That would only be true in the way we use the word if other ravens also “addressed” the speaker using its personal identification call — and that’s exactly what ravens do. They remember the names of other ravens for years, even if they’ve had no contact.

If an acquaintance appears in the sky and calls his or her name from afar, there are two possible responses. If the returning raven is a former friend, the other ravens answer in high-pitched, friendly voices. However, if the raven is unpopular, the greeting is low-pitched and brusque. Similar observations have been made for human greetings.

It’s quite difficult to discover the names animals use for each other. It’s much easier if we call them using a name we’ve chosen for them and see if they react. People who own a single pet now come to the next hurdle. How do we know that, for instance, our dog Maxi doesn’t hear her name and interpret it to mean simply “Hi” or “Come here”? It would be easier to tell if you owned more than one dog, but here I would like to return to the intelligent pig.

Researchers have studied pigs for precisely this attribute. The reason for the research was the widespread pushing and shoving in modern pens. Farmers used to pour feed into a long trough so all the pigs could eat at the same time. Today, feed is distributed automatically with the help of computers that calculate the amount for each individual pig, and because the equipment is expensive, there’s not enough money for many machines and so not all the pigs in one pen can eat at the same time.

They have to wait their turn, and pigs are as impatient with rumbling stomachs as we are. They jostle each other in line, sometimes even injuring each other.

To help bring some civility back into the process, researchers from the Friedrich-Loeffler-Institut (the German Federal Research Institute for Animal Health), specifically from the institute’s pig team, tried to teach manners to pigs at an experimental farm in Mecklenhorst in Lower Saxony. Here, using small school “classes” of eight to 10 animals, they trained yearlings to respond to individual names.

The young porkers were particularly good at catching on to three-syllable female names. After one week of training, the pigs went back into a pen in a larger group. And now meal times got really interesting. Each pig was called up by name when it was its turn. And, as it turns out, it worked. As soon as “Brunnhilde” rang out from the loudspeaker, the only pig that sprang up and raced to the trough was the one that had been called, while all the others continued doing whatever it was they were doing, which for most of them was simply snoozing.

The measured heart rate of the other pigs did not increase, and the only pig that registered a higher pulse was the one that had been summoned. The new system had a success rate of 90 per cent, and is one way to bring peace and order to the pens.

But does this heartwarming discovery have a wider significance? The ability to associate oneself with a particular name presupposes self-awareness. And that is one step above consciousness. For whereas the latter merely implies thought processes, with self-awareness we’re talking about recognizing who you are, a sense of self.

To test whether animals possess this ability, science came up with the mirror test: animals that recognize that the reflection in the mirror is not another animal but their own image are supposedly self-aware. The inventor of this experiment was one Gordon Gallup, who painted a coloured spot on the forehead of anesthetized chimpanzees. Then he placed a mirror in front of the drugged animals and waited to see what happened when they woke up.

No sooner did the apes glimpse their reflections through eyes still blurry with sleep than they began to try to rub the colour off. Clearly they understood immediately that they were the ones looking out from the gleaming glass. Since then, this test has been considered proof that animals that pass it possess self-awareness. (Incidentally, children do not pass this test until they are about 18 months old.)

Primates, dolphins, and elephants have all passed the test since it was first introduced and, accordingly, have risen in the eyes of researchers.

People were surprised when crows also recognized their own reflection, as did magpies and ravens. Thanks to corvids’ intelligence, people have started referring to these birds as “feathered apes.” Not much more came to light in connection with this discovery for a long time, until suddenly pigs began popping up in scientific papers.

Pigs? They, too, passed the test, although unfortunately they didn’t score a pet name (“factory farm apes” comes to mind) for if they had, how could anyone have continued to treat pigs as inhumanely as they are treated today? People don’t even credit these intelligent animals with feeling pain, as proven by the fact that, in Germany, it is legal to castrate piglets only a few days old without anesthetic, and it will continue to be legal until 2019, because it’s quicker and cheaper that way.

But back to the mirror. Pigs know how to use mirrors for more than just self-contemplation. Donald M. Broom and his team at the University of Cambridge placed food behind a barrier. Then the pigs were positioned so that they could only see the food using a mirror placed in front of them. Seven out of eight pigs took just a few seconds to realize that they had to turn around and go behind the barrier to reach the tasty treats. To do this, they not only had to recognize themselves in the mirror but also had to consider spatial relationships in their surroundings and their own place in them.

Despite these results, we should be careful not to set too much store by the results of the mirror test, particularly when it comes to animals that do not pass it. First off, when dogs anointed this way look at their reflection and do not react, that may not mean anything. How are we to know whether the spot on their face bothers them in the slightest? And even if it does, perhaps they don’t know how the mirror works. Perhaps they think it’s a colourful picture or, at most, a video like the ones we watch on a television.

Let’s return to naming, and now Canadian squirrels take centre stage. When investigating cases of adoption, researchers discovered that these arboreal imps adopted only related young. But how did they know which ones were their nieces, nephews or grandkids?

Researchers at McGill University suspect that adults’ vocalizations have an important role to play here. Every squirrel has a distinctive call, and the solitary creatures use these calls to recognize one another. After all, they don’t see each other very often because their territories rarely intersect, so the only way they can communicate is by sound.

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What is even more astounding is that some animals come looking when they stop hearing their relatives’ calls. This means they have to leave their own territory and enter an unfamiliar one. Does that make them nervous? We can only speculate about that, but we do know that when they come across orphaned young during their forays into alien territory, they take the helpless young into their care.

Science is only just beginning to explore this subject, like so many others. As I’ve just explained, naming is an advanced form of communication that many animals have mastered. Even fish, which we think of as silent creatures, are in on this skill, but the only thing we know right now is that they use the sounds they make to find a partner or to defend their territory.

Excerpted from The Inner Life of Animals: Love, Grief, and Compassion — Surprising Observations of a Hidden World by Peter Wohlleben, published Nov. 7 by Greystone Books and the David Suzuki Institute. Reproduced and condensed with permission from the publisher.