Why Newborn Chicks Love Objects That Defy Gravity

In a lab in London, newborn chicks took the first steps of their life and unwittingly became part of solving one of the brain’s bigger mysteries.

In a simple test, researchers placed the downy animals, hatched after less than a day in complete darkness, one at a time into a special box. Two screens on opposite sides of the box played videos of moving orange balls, one moving upward, the other downward. By design, the videos were the first things these chicks saw in their lives—and, thanks to their sideways-facing eyes, they saw both at once.

Computer software tracked the chick’s movements, and the results were clear. Over the course of 20 minutes, most of the chicks hesitantly toddled over to the end of the box with the upward-moving ball, confirming what scientists suspected: Even without any previous visual experiences, chicks are attracted to objects moving against gravity.

The discovery is the latest development in the scientific investigation of how the minds of animals and humans prepare them for life. The preference for upward-moving objects represents the first time a stimulus this simple has been shown to trigger attention in chicks before they have any life experience. Elisabetta Versace, a comparative neuroscientist at Queen Mary University of London, and her colleagues published the finding Tuesday in Biology Letters.

“Our focus is to try and understand what are the building blocks that, from the beginning of life, help us to orient ourselves in the world,” says Versace, the lead author of the new study and head of the Prepared Minds Lab at Queen Mary.

Biologists call the mechanisms that assist animals in their earliest moments “evolutionary predispositions” or “priors.” These impulses are built into the brain from birth and guide an animal’s decisions before it has any lived experiences.

Elisa Raffaella Ferrè, a cognitive neuroscientist at the University of Birkbeck and co-author of the new study, arrived at the chick experiment from her research on how the human brain adapts to gravity. Studying how predispositions work in humans is difficult, says Ferrè, as babies take time to develop complex skills. By the time human infants are able to easily move and respond to stimuli, they have already spent significant time learning. Chicks, however, can perform relatively complex actions very soon after birth. That makes them prime candidates for exploring how predispositions function.

“[In our experiment] the chick has no experience whatsoever—never seen any object, anything moving around, zero,” Ferrè says.

When the chicks observed the balls, they not only investigated the ball that appeared to work against the pull of gravity, but also approached it first and faster, in addition to spending more time exploring it.

The behavior not only shows an innate predisposition for objects that move against gravity, Ferrè says, but it also shows that the chicks have some understanding—whether conscious or unconscious—of how gravity works.

Why this preference for objects that move against gravity exists at all remains unclear. The researchers of this study speculate that it could be because the ability to self-propel against the force of gravity is more likely to be associated with living animals.
“Going against gravity in a consistent way is associated with animate objects in the ecological world,” Versace says, “because usually you see that water flows down or a rock falls down.” Inanimate objects, on the other hand, are unlikely to move consistently against gravity.

“We don’t know if [the chicks] think, ‘Oh, this could be my mom,’” Versace says. “They might simply go in that direction and interact.” But from an evolutionary perspective, a chick that is more attracted to upward-moving objects will have more interactions with other animals, giving it a social advantage.

Still, Versace says that despite the influence these predispositions can have, they do not guarantee a chick will always choose to investigate an upward-moving object. They simply make it more likely that a chick will be attracted to it.

The newly released article is consistent with previous research, according to Orsola Rosa Salva, a comparative psychologist at the University of Trento who was not involved in the study. Studies with chicks have shown predispositions to go toward face-like shapes and shapes that can move by themselves. “They seem to really care about self-propulsion,” she says.

What Salva wants to see next in this field are experiments that begin to pinpoint what areas of the brain are active when predispositions are triggered, so scientists can better understand how the mechanisms work. Versace hopes that future research can offer insights into the way the brain is organized to make sense of the world.

“I’m very fascinated by the fact that a brain that is very tiny—the chick’s is just a couple of grams—can at the beginning of life, make such sophisticated computations,” she says.