Two hermit crab on andaman sea beach

            Animal personalities, A few years ago, Christian Rutz began to wonder if he was giving his ravens enough trust. Rutz, a biologist at the University of St. Andrews in Scotland, and his team captured wild New Caledonian crows and challenged them with puzzles made from natural materials before releasing them again. In one test, the birds faced a log pierced with holes that contained hidden food, and could retrieve the food by bending a plant stem into a hook. If a bird did not try within 90 minutes, the researchers removed it from the data set.

But Rutz says he soon began to realize that he wasn’t really studying the skills of New Caledonian crows. He studied the skills of only a subset of New Caledonian crows, which quickly approached a strange log they had never seen before—perhaps because they were particularly brave or reckless.

The team changed their protocol. They began giving the more hesitant birds an extra day or two to get used to their surroundings, then tried the puzzle again. “It turns out that many of these retested birds suddenly become engaged,” Rutz says. “They just needed a little extra time.”

Scientists are increasingly realizing that animals, like humans, are individuals. They have different tendencies, habits, and life experiences that can affect how they perform in an experiment. This means, some researchers argue, that much of the published research on animal behavior may be biased. Studies that claim to show something about a species as a whole — that green sea turtles migrate a certain distance, say, or how loggerheads respond to a rival’s song — may say more about individual animals that have been captured or housed on a certain way, or that share certain genetic characteristics. This is a problem for researchers who seek to understand how animals sense their environment, acquire new knowledge, and live their lives.

“The samples we take are quite often highly biased,” Rutz says. “It’s something that’s been in the air in the community for quite some time.”

In 2020, Rutz and his colleague Michael Webster, also from the University of St. Andrews, proposed a way around this problem. They called it WEIRD.

This video from one of Christian Rutz’s experiments shows a New Caledonian wild crow bending a plant stem into a hook to retrieve food from a hole. Although some birds were hesitant to approach the materials at first, Rutz realized that many of them could solve the puzzle with extra time.


Personalities aren’t just for people/Animal personalities

Why “WEIRD”? In 2010, Art article in Behavioral and brain sciences suggest that the people studied in much of the published psychology literature are WEIRD—coming from Western, educated, industrialized, affluent, and democratic societies—and are “among the least representative populations one can find to generalize about people “. Researchers can draw sweeping conclusions about the human mind when they’ve only really studied the minds of, say, students at the University of Minnesota.

A decade later, Rutz and Webster, drawing inspiration from WEIRD, published an article in the journal Nature Called “How WEIRD are your research animals?

They suggested that their fellow behavioral researchers consider several factors for their study animals, which they called social background, trapability and self-selection, rearing history, habituation and habituation, natural changes in responsiveness, genetic makeup, and experience.

“I first started thinking about these kinds of biases when we were using minnow net traps to collect fish for experiments,” says Webster. He suspected—and then confirmed in the laboratory — that more active waders are more likely to swim into these traps. “Instead, we’re trying to use nets,” says Webster, to catch a wider variety of fish.

This is Trappability. Other factors that can make an animal more susceptible to trapping than its peers, besides activity level, include a bold temperament, lack of experience, or simply being more eager for bait.

Other research shows that pheasants roost in groups of five present better on a learning task (finding which hole has food) than those placed in groups of only three—this is a social background. jumping spiders were bred in captivity less interested in prey than wild spiders (History of husbandry) and honey bees learn best morning (natural changes in responsiveness). And so on.

Biases in experiments can have surprising sources. In one study, pheasants did better on a learning task when housed in larger groups. (Credit: Budimir Jevtic/Shutterstock)

It may be impossible to remove all bias from a group of study animals, Rutz says. But he and Webster want to encourage other scientists to consider WEIRD factors in every experiment and be transparent about how those factors may have influenced their results.

“We assumed we could do an experiment the way we do chemistry—by controlling a variable and not changing anything else,” says Holly Root-Gutteridge, a postdoctoral researcher at the University of Lincoln in the United Kingdom who studies dog behavior. But research reveals individual patterns of behavior – scientists sometimes call it personality — in all kinds of animals, from monkeys to hermit crabs.

“Just because we haven’t given animals credit for their individuality or distinctiveness before, doesn’t mean they don’t have it,” says Root-Gutteridge.

This failure of human imagination, or empathy, taints some classic experiments, note Root-Gutteridge and coauthors in 2022 paper focused on animal welfare issues. For example, experiments by psychologist Harry Harlow in the 1950s involving baby rhesus macaques and fake mothers made of wire are said to have provided insight into how human infants form attachments. But given that these monkeys were torn from their mothers and kept in unnatural isolation, can the results really be generalized, the authors ask? Or do Harlow’s findings only apply to his uniquely traumatized animals?

Looking for more imitators  /  Animal personalities

“All this individual behavior, I think it’s a trend in the behavioral sciences,” says Wolfgang Goimann, a behavioral ecologist at the Max Planck Institute for Biological Intelligence and editor-in-chief of Ethology. The magazine officially adopted the STRANGE framework in early 2021 after Rutz, who is one of the magazine’s editors, pitched it to the board.

Goiman didn’t want to create new hoops for already overworked scientists to jump through. Instead, the journal simply encourages authors to include a few sentences in their methods and discussion sections, says Goiman, noting how STRANGE factors might affect their results (or how they accounted for those factors).

“We want people to think about how representative their survey actually is,” says Goiman.

Psychological researchers have also questioned whether research on a narrow group of people, such as Western college students, really says much about human beings in general. (Credit: Gorodenkof/Shutterstock)

Several other journals have recently adopted the STRANGE framework, and since their 2020 report, Rutz and Webster have held workshops, panel discussions, and conference symposia. “It’s grown into something that’s bigger than we can run in our spare time,” Rutz says. “We’re excited about it, really excited, but we had no idea it was going to take off the way it did.”

His hope is that widespread adoption of STRANGE will lead to discoveries in animal behavior that are more reliable. The problem of studies that cannot be replicated has recently attracted a lot of attention in some other sciences, particularly in human psychology.

Psychologist Brian Nosek, executive director of the Center for Open Science in Charlottesville, Va., and co-author of the 2022 paper.Reproducibility, robustness, and reproducibility in psychological science” in Annual Review of Psychology, says animal researchers face similar challenges as those focusing on human behavior. “If my goal is to assess human interest in surfing and I conduct my study on a California beach, I’m not likely to get an assessment that generalizes to humanity,” says Nosek. “When you replicate my study in Iowa, you may not replicate my finding.”

The ideal approach, Nosek says, would be to gather a study sample that is truly representative, but that can be difficult and expensive. “The next best alternative is to measure and be clear about how the sampling strategy might be biased,” he says.

That’s exactly what Rutz hopes STRANGE will achieve. If researchers are more transparent and attentive to the individual characteristics of the animals they study, he says, others may be better able to replicate their work—and be sure that the lessons they draw from their study animals are meaningful. and not quirks of experimental settings. “That’s the ultimate goal.”

In his own experiments with crows, he does not know whether giving the shyer birds extra time changed his main results. But it gave him a larger sample size, which could mean more robust statistical results. And, he says, if studies are better designed, it could mean fewer animals need to be caught in the wild or tested in the lab to reach firm conclusions. Overall, he hopes STRANGE will be a victory for animal welfare.

In other words, what’s good for science can be good for animals — seeing them “not as robots,” says Goiman, “but as individual beings who also have value in their own right.”


Elizabeth Preston is a freelance science journalist who lives in the Boston area with her family and is working on a book about the evolution of parenting. She suspects her interception ability is average.

This article originally appeared in Knowable Magazine, an independent journalistic venture from Annual Reviews. You can read the original here.

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