Some cows are optimists. But some aren't.
While it's tempting to expect herd animals like cows to all be the same, a new study suggests that, in fact, they think and act very differently -- like people, some are more pessimistic than others.
The University Of British Columbia study, published Jan. 23 in "Scientific Reports," observed the actions of 22 calves to come to this conclusion.
The calves were trained to expect that a bottle placed in a hole on one side of the room would contain milk, while a bottle on the other side would only blow a puff of air at the calves' muzzles.
They then placed a bottle in a hole somewhere between the "good" and "bad" bottles, with the thought that the optimistic calves would be willing to approach the new bottle (even if it was placed near the empty bottle), while the pessimistic calves would not, for fear of getting a puff of air in the face.
The researchers found something interesting: while the calves varied in their responses, each individual calf consistently made the same choice when it came to the new bottle, even when tested three weeks apart.
This led the researchers to conclude that pessimism in a particular calf was a consistent, overarching trait, not just the result of a temporary mood or emotion. The study also suggests that this pessimism is closely linked to fear.
"Calves that were more fearful were also more likely to view the glass as half empty," said professor Marina von Keyserlingk, who co-authored the study.
Von Keyserlingk believes that studies like this are important in understanding individual animals.
"Sometimes we are tempted to see only the herd, even though this herd consists of different individuals who cope differently with stressful events. It's important to consider the individual's perspective, because even if conditions are good on average, some animals may still suffer."
The team hopes to use this research to improve the lives of calves like these.
"The next step in our research will be to understand what type of rearing conditions help ensure that an individual animal has a good life," von Keyserlingk said. "For example, more pessimistic calves may require different types of housing and management than we currently provide."
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