Humans and octopuses are separated by 500 million years of evolution, but appear to share one unusual thing in common: Both get high on the party drug ecstasy, according to a new study.
In humans, ecstasy—also known by its chemical name 3,4-Methylenedioxymethamphetamine (MDMA)—binds to a protein in neurons. The genetic code for this protein is stored in a gene called SLC6A4. When MDMA docks to this protein, our brain cells start to pump out massive quantities of serotonin, the chemical responsible for the warm and friendly feelings of ecstasy’s high. Octopuses’ genomes also contain a copy of SLC6A4, so researchers wondered whether the drug would have a similar effect on them.
The team placed four California two-spot octopuses (Octopus bimaculoides, pictured) in a tank containing a liquefied version of ecstasy, which the animals absorbed through their gills. Next, the scientists placed the octopuses individually into a three-chambered water tank for 30 minutes: one empty; one with a plastic action figure, an object that might pique the octopus’s curiosity; and one with a female or male laboratory-bred octopus under a cage.
Octopuses are usually antisocial outside of their mating season, but while under the influence, all four spent several minutes longer with the other octopus than in the solitary chamber or the one with the interesting object, the team reports today in Current Biology. They also tended to hug and put their mouthparts on the cage in an exploratory, nonaggressive way—similar to their mating season behavior.
The findings suggest that, despite the huge evolutionary gulf that separates us, humans and octopuses appear to have similar brain chemistry guiding their social behaviors. Still, with such a small sample size, the scientists caution that the results need to be confirmed in other experiments before octopuses are used to investigate the workings of the human brain. But for now, they appear to have discovered a surefire way to liven up an octopus garden party.