Johns Hopkins researchers got octopuses high on MDMA, and their findings might lead to a deeper understanding of social interaction — not just in the fascinating cephalopods, but in humans, too.
In a new study published Thursday in the journal Current Biology, researchers soaked octopuses in diluted MDMA, which they absorbed through their gills, and then placed them in tanks with three separate chambers: one empty, one containing another octopus, and one containing a plastic toy. Octopuses are normally extremely solitary, antisocial and aggressive with each other — when mating, males deposit their sperm as quickly as possible and then flee so the females won’t eat them — but on the drug, they were downright friendly. During the control test where they were placed in the same tanks while sober, they either avoided the other octopuses entirely, or tentatively explored their areas with one tentacle. On the drug, they spent far more time in the chamber containing the other octopus.
“It’s not just quantitatively more time, but qualitative. They tended to hug the cage and put their mouth parts on the cage,” Gül Dölen, M.D., Ph.D., assistant professor of neuroscience at the Johns Hopkins University School of Medicine and the lead investigator conducting the experiments said in the researchers’ press release. “This is very similar to how humans react to MDMA; they touch each other frequently.”
She told the Guardian the octopuses were “exposing parts of their body that they don’t normally expose to another octopus,” also similar to the way some humans react to the drug.
Octopus brains and human brains are structurally very different, with octopuses’ neurons distributed throughout their arms and operating seemingly independently. But these researchers found that despite these differences, the mechanism that binds serotonin to neuron membranes is nearly identical in humans and octopuses. This same mechanism is how MDMA binds to neurons and alters humans’ mental states, so they decided to see how it would impact octopuses.
“Why an octopus?” Dr. Dölen explained in an email, “I think there are a lot of reasons to study octopuses for human disease. Octopuses are known for a number of remarkable abilities, including limb regeneration, camouflage, temperature adaptation, and advanced cognition. Recent studies have uncovered exciting novel mechanisms underlying many of these abilities, which have been harnessed for innovative tissue engineering and robotics applications.”
“The other major argument for studying octopuses is exactly that they are so evolutionarily far away from us,” she added. This allows researchers to study complex cognitive behaviors, “without getting bogged down in the incidental (necessary but contingent) organization of brains.”
“For example,” Dr. Dölen said, “based solely on the mammalian brain, you might be tempted to argue that performing cognitive behaviors requires having a cerebral cortex, because across mammals the bigger the cortex, the more complex the cognitive abilities of the species. But of course what the octopus tells us is this is not universally true, since octopuses don’t have a cortex, and yet they can perform amazing cognitive feats.”
Until now, most research into human social behavior has been based on our complex circuitry, but these new findings suggest that examining basic brain chemistry could be more significant than previously thought, and could lead to a deeper understanding of how serotonin impacts social interaction.