The Science Behind 'Pessimist Cows' Is Truly Heartbreaking

A lot of fascinating science goes on in the dairy industry. Most of it comes from researchers trying to get improved flavors, nutrition, and yields from dairy cows, but some animal behavioral scientists are also focused on finding ways to make the industry more humane. Dr. Daniel Weary is one of them. He and his team at the University of British Columbia study ways of raising the quality of life of dairy cows. Weary's research has consistently demonstrated how cows are both logically and emotionally intelligent, and his team produced evidence in a 2014 paper that calves can even become pessimists after they're separated from their mothers.

Many animals are smarter than you might think, and cows are one of them. Research has shown cows possess complex social bonds, have excellent long-term memory, and even form lifelong friendships. Most importantly for the dairy industry, mother cows (or "dams") and their calves develop strong emotional bonds that start to form as soon as the calf is born. It was this bond between mother and calf that Weary and his team sought to investigate.

Dairy farms often separate calves from their mothers within a couple of days of birth. Males may be sold for veal, while female calves are dehorned, their horn roots removed with saws, chemicals, wires, or other painful methods. To investigate how such trauma could affect dairy calves' emotional states, Weary's team trained calves to associate red-colored screens with treats. Then, when the team introduced mixed shades of the color, the calves that hadn't been weaned were willing to approach the new "ambiguous" screens while those that had been recently separated from their mothers and dehorned were more unwilling. In a word, the traumatized calves had become pessimists and often refused to play along.

Calling a cow a "pessimist" may be somewhat anthropomorphizing, but there is real evidence to suggest that animals can develop personality traits that manifest as persistent behaviors. After all, humans aren't the only animals that cry. In studies like Weary's, such traits are observed through the lens of "judgement biases." When a calf is reluctant to explore new things, such as a new screen color that it hadn't been exposed to before, it's likely because the calf has developed a negative judgement bias to unfamiliar stimuli. 

As Weary's research demonstrates, such changes in an animal's disposition can be caused by trauma. The study didn't just reward its bovine subjects for approaching red screens; it also punished them by putting them in time-out for approaching white screens. When the two colors were mixed into in-between shades of pink, the calves that hadn't been permanently separated from their mothers were still willing to risk losing their chance of getting a treat by approaching the ambiguities. But after separation and dehorning, calves were 10% less likely to take the risk. Thus, their aversion to the punishment of a "time-out" was greater than their desire to earn a reward. In other words, they tended to expect the worst — the hallmark of pessimism.

The 21st century has reshaped our understanding of bovine psychology. A 2009 paper from the University of Paris suggested that cattle can easily recognize and distinguish other individuals from the herd, while a 2019 study from the University of Sydney demonstrated that vocalizations among cattle are affected by emotional states, meaning they may communicate their feelings to each other. Such new methodologies and approaches continue to shine light into the complex inner worlds of cows.