By studying the genome of a kind of octopus not known for its friendliness toward its peers, then testing its behavioral reaction to a popular mood-altering drug called MDMA or ‘ecstasy,’ scientists say they have found preliminary evidence of an evolutionary link between the social behaviors of the sea creature and humans, species separated by 500 million years on the evolutionary tree.
It sounds like the start of a bad party joke: What do you get when you mix two octopuses, a Star Wars action figure and ecstasy? But a recent experiment did just that, and it revealed that at a neuromolecular level, we have more in common with these tentacled cephalopods than you might think.
Neuroscientist Gül Dölen of Johns Hopkins University and fellow researcher Eric Edsinger, an octopus researcher at Marine Biological Laboratory in Woods Hole, Massachusetts, arranged an experiment with two octopuses and either a stormtrooper or Chewbacca action figure. With the toy in a chamber on one side of a tank, and a cephalopod friend in another chamber, a sober octopus would spend more time with the inanimate object. But add a little MDMA to the equation, and the doped-up octopus starts to get cozy with its pal, as reported today in the journal Current Biology.
“I find it fascinating that the experimenters were able to chemically elicit prosocial behavior in octopuses, which are commonly quite nervous about approaching conspecifics,” says David Scheel, a marine biologist who specializes in octopus behavior at Alaska Pacific University and was not affiliated with the new study.
MDMA, called ecstasy or Molly when taken recreationally, essentially causes a flood of serotonin in the brain. The drug is known for the happy-go-lucky, heart-eyed effect it has on people. By studying ecstasy’s effects on octopuses, the team realized something that they didn’t expect—the same genetic and neurological infrastructure that’s linked to prosocial behavior in humans is also present in other organisms. Specifically, a gene called SLC6A4 codes a serotonin transporter in both humans and octopuses that’s known to be the binding site of MDMA.
“The impact MDMA has on the social behavior in this study is compelling and may help fill in many of the missing pieces for understanding the role of serotonin in social behaviors,” says L. Keith Henry, a molecular neuroscientist at the University of North Dakota who was not involved in the study.
Because vertebrates diverged from invertebrates more than 500 million years ago, it may come as a bit of a surprise that humans and octopuses share common neurological functions at all—our last shared ancestor probably resembled some kind of worm-like sea creature. It’s easy to assume that people don’t have much in common with our eight-legged, under-the-sea friends.
For starters, our two arms and two legs pale in comparison to the eight suction-cup-covered appendages that give the octopus its name. These versatile sea creatures have three hearts, but no bones, and they’re known for squirting ink at their predators (an ability we regrettably lack). The octopus is a master of disguise, using camouflage to blend in naturally with its surroundings—something we need special gear to achieve. And most relevant to this study, octopuses are asocial and solitary beings, avoiding others of their own kind unless it’s time to mate.