“The most surprising thing was that they were able to tolerate delays of 50 to 130 seconds,” Schnell says. “That’s comparable to what we see in large-brained animals such as chimps, crows, and parrots.”
The cuttlefish that waited the longest for their favorite foods also performed better during learning tests, a link that previously has only been shown in humans and chimpanzees. In the future, Schnell and her team plan to broaden the battery of tests to explore that connection further.
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As with humans, however, not every cuttlefish was a star pupil. “You do get the impatient ones,” Schnell says. “There was one cuttlefish that would squirt me with her siphon repeatedly until I would come over to feed her. They have so much character.”
To ensure the animals were actually weighing the options and using that information to inform their decision, the researchers introduced a different pairing. In this setup, one chamber contained king prawn, and the other an unobtainable shrimp.
“If their self-control is flexible—and I hadn’t just trained them to wait in any context—you would expect the cuttlefish to take the immediate reward” in this case, says Schnell. “Even if it’s their second preference.” That’s exactly what happened. What’s more, this showed that king prawn hadn’t been taken off the menu.
“That’s something you have to test when you’re looking at self-control with different-quality foods,” notes Schnell.
“If I give a child an apple and say, ‘If you wait 15 minutes, you can have this chocolate bar,’ most of them would probably say, ‘No problem. I want the chocolate,’” Schnell adds. The team needed to be sure that cuttlefish would take their version of an apple if it was the only option.
There’s another sign that may also indicate the cuttlefish were deliberately waiting. During some trials, cuttlefish appeared to move their bodies away from the immediate reward. “We see this in some other animals as a coping mechanism to try and resist temptation and wait for the better reward,” Schnell says. Parrots close their eyes; corvids and dogs turn away; chimpanzees try to distract themselves. Schnell doesn’t know yet if the cuttlefish are doing something similar, but the possibility is intriguing.
Jennifer Vonk, a comparative and cognitive psychologist at Oakland University in Michigan who was not involved in the study, is excited to see cuttlefish exposed to these kinds of tests. Testing a wider variety of species, she explains, can help us unravel the mystery of what drives cognitive prowess.
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The lineage that led to cuttlefish and their kin split from the vertebrate lineage more than 550 million years ago. Their most recent common ancestor—a wormlike creature with a very simple nervous system—wouldn’t have had these abilities. This means that any cognitive traits shared by humans and cuttlefish evolved independently.