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New book explores the secret emotional lives of animals

In his new book The Inner Life of Animals, Peter Wohlleben offers a compassionate glimpse into the surprisingly complex emotional lives of creatures both wild and domestic 

  • Nov 04, 2017
  • 1,194 words
  • 5 minutes
the inner life of animals peter wohlleben book cover Expand Image

With his latest book, The Inner Life of Animals: Love, Grief, and Compassion—Surprising Observations of a Hidden World, Peter Wohlleben continues to carve out the things-we-never-knew-and-take-for-granted-about-the-natural-world niche in the same way that helped make his first book, The Hidden Life of Trees, such a surprise hit.  

Wohlleben, a German forester, doesn’t shy away from emotion in his descriptions of, say, the “private hell” of wood mice being hunted by a marten. Instead, he deploys it in an effort to get readers to connect and empathize with animals. That he does so without minimizing the scientific explanations his topic demands is what makes this compassionate look at the wild and domestic creatures we share the world with such a thought-provoking read.

In advance of the book’s Nov. 7 publication, here is an excerpt from from the chapter titled “Empathy.”


The commonest mammals in the wood are also among the smallest representatives of this class of vertebrates: wood mice. They are pretty little things but, because they are so small, they are difficult to observe and therefore many woodland walkers are not that interested in them. I didn’t realize how many of these tiny creatures are scurrying around in the underbrush until I had to stand around for a long time in one spot in the woods waiting for an appointment with someone interested in our woodland burial ground. Wood mice are omnivores, and they spend their summers under old beech trees living the good life. There are buds, insects, and other small animals aplenty, so they can take it easy and concentrate on bringing up their offspring. But then winter approaches. To avoid the worst of the cold, they set up their living quarters at the foot of mighty trees, usually where multiple roots cover the forest floor. The roots create natural hollows and all the mice need to do is enlarge them a bit for their purposes. Wood mice are social creatures, so a number of them usually share the same space.

When there’s snow on the ground, I can sometimes spot the traces of a drama that played out among the roots. A trail of small paw prints leads to the trunk of a beech — a marten on the move. And martens love mice for breakfast. The tracks lead to a root hollow, and now I can clearly see signs of a whole lot of scraping and scratching. Not only did the marten nonchalantly dig up the hidden hoard of mouse food, but it might even have dug up one of the mice. What must that have been like for the other mice? Were they simply afraid of the marten or did they also realize that its activities caused one of their own to suffer?

Clearly they were aware of their fellow mouse’s suffering, as researchers at McGill University in Montreal have discovered. The researchers observed evidence of empathy in the tiny mammals, the first non-primates in which such emotions have been documented. The experiments themselves, however, were anything but empathetic. The researchers caused painful injuries by injecting acid into their tiny paws, or, in another experiment, pressed these sensitive body parts onto hot surfaces. If the mice had observed other mice experiencing similar torture, they experienced considerably more pain than if they went into the experiment unprepared. On the flip side, the presence of another, less-traumatized mouse made it easier for the test subject to endure the pain. What was important was how long the mice had known each other. There were clear effects of empathy if the animals had been together for more than fourteen days, which is typical for wild wood mice in Central European woodlands.

But how do mice communicate amongst themselves? How do they know another mouse is suffering and experiencing a private hell? To find this out, the researchers blocked their senses one after the other: sight, hearing, smell, and taste. And although mice like to communicate using smell and make shrill ultrasonic calls when alarmed, surprisingly enough, in the case of empathy, it is the sight of suffering companions that triggers their response. So when a marten fishes a wood mouse out from a cozy root hollow in winter, the other mice must endure their own few seconds of terror. We don’t yet know how long feelings of empathy last. So when I come across the marten’s tracks in the snow, I have no idea whether the sympathetic responses of the wood mice and the upset they cause are still distressing the tiny inhabitants below.

But how does empathy work with mice that have only recently arrived and therefore are not yet integrated into the group? Clearly, it is felt considerably less intensely, and in this respect mice are surprisingly no different from people, which the researchers at McGill University also discovered. They compared the empathetic behavior of students and mice, and concluded that empathy for family members and friends is much more pronounced than empathy for strangers. The reason was the same for all the experimental subjects—stress. Stressed individuals are less affected by the suffering of others. The strangers themselves are often the cause of this stress, and the sight of them releases the hormone cortisol. To verify this, researchers carried out another experiment, this time using a drug that blocked the production of cortisol in both students and mice, and feelings of empathy increased again.

Even domestic pigs put in another appearance when it comes to empathy. In this case, I’m thinking of the experiments of Dutch scientists at Wageningen University and Research Centre in charge of the experimental pens at the Swine Innovation Centre in Sterksel, where they played classical music to the pigs. Don’t worry, the researchers weren’t trying to find out if pigs are fond of Bach. Rather, they got the pigs to connect the music to small rewards, such as chocolate-covered raisins hidden in the straw. Over time, the pigs in the experimental group came to associate music with particular emotions. And now things got interesting, for other pigs were added that had never heard such sounds and therefore had no idea what they meant. Despite this, they experienced the same emotions the musical pigs experienced. If the musical pigs were happy, the newcomers also played and jumped around; in contrast, if the musical pigs were so scared that they urinated on themselves, the newcomers caught the feeling and exhibited the same behavior. Pigs clearly can experience empathy. They can pick up on the emotions other pigs are feeling and experience those feelings themselves — a classic expression of empathy.


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