Unless they’re mating, octopuses want nothing to do with each other. Put two in the same tank, and they will usually stay far away from one another — or try to kill and eat each other. But, a study published this week in Current Biology found that when scientists spiked the water in their tank with MDMA, a psychoactive compound commonly known as Ecstasy, something remarkable happened — the prickly octopuses transformed into warm and fuzzy creatures.
Octopuses are separated from human evolution by 500 million years. They have a complex nervous system that has evolved in a dramatically different way from that of humans, with bundles of neurons in each of their eight legs connected to a central bundle of neurons. Yet, just like humans, on MDMA, the normally grumpy octopus becomes friendly and sociable.
“They have this huge complex brain that they’ve built, that has absolutely no business acting like ours does — but here they show that it does,” Judit Pungor, a neuroscientist at the University of Oregon, told NPR. “The fact that they induced this very sort of gentle, cuddly behavior is really pretty fascinating.”
While dramatically different in structure, after sequencing the genome of the California two-spot octopus (Octopus bimaculoides) last year, researchers found that octopuses and humans are encoded to produce a protein that binds the neurotransmitter serotonin to brain cells in a very similar manner. It is this same protein that is affected by MDMA.
This result got Gul Dölen, a neuroscientist at Johns Hopkins University, curious about whether MDMA would produce the same effect on the anti-social octopus as it does in humans.
To find out, Dolen and her colleague Eric Edsinger from the Woods Hole Marine Biological Laboratory, placed a pair of octopuses into a tank with three chambers. In the first chamber, they placed a toy, the second was empty, and in the third they confined one of the octopuses. The other octopus was allowed to roam freely.
The research team then logged the time spent in each chamber normally and again after the water in the tank was laced with MDMA. Initially, the octopuses loitered more in the tank with the toy with it. But, after the researchers dosed the water in the tank with MDMA, the free-roaming octopus chose to spend more time in the chamber with the other octopuses. Not usually touchy feely creatures, after being given MDMA, the octopuses actually started hugging.
“My lab has been studying MDMA for a long time, she said, “and we have worked out a lot of neural mechanisms that enable MDMA to have these really, really profound pro-social effects.”
MDMA, has long been known as a party drug that inspires a sense of euphoria and empathy along with a desire to dance all night. But, serious interest in MDMA has grown as researchers have begun discovering promising applications of the drug in treating PTSD and other disorders.
The study in octopuses helps give scientists a better understanding of how the neurological mechanisms regulating social behavior evolved. The presence of a similar role of serotonin in the octopus, which parted evolutionary ways with humans far in the distant past, suggests that the physical structures that underlie emotional connection are deeply wired.
There are promising signs that further research into the drugs effects can help unravel how social behavior is wired into our brains. “Even though octopuses look like they come from outer space, they’re actually not that different from us,“ Dr. Dölen told the New York Times. “We need to be taking full advantage of these compounds to see what they’re doing to the brain.”