Taking MDMA may make some people feel like an octopus, but does an octopus feel like a human when they roll? According to new research published today in Current Biology, the answer is yes. When given the party drug, a relatively antisocial, solitary species of octopus became more social, engaged, and generally interested in its surroundings.

Why would one want to dose up an octopus? To better understand the evolutionary heritage of social behaviors across the animal kingdom, of course. (Sidebar: How do we get in on that research lab?)

To do this, researchers divided an aquarium into three equal-sized partitions: the first held a new object (we’ll call this the “toy room”), the second held nothing, and the third housed another octopus restrained in a plastic container that the other octopus could see, touch, and pick up on chemosensory cues, but not come into the same space. The researchers then placed the experimental octopus in the center and recorded how much time an octopus spent in each of the chambers over a 30-minute test session.

When the octopuses were rolling, they exhibited some out-of-character behavior. Not only did they spend more time with other octopuses, but they also engaged in “extensive ventral surface contact” – touching of the other animal’s underside – in an exploratory, unaggressive way. When you have eight arms with thousands of highly sensitive suction cups, it's no wonder.

Although they’re evolutionarily separated from humans by more than 500 million years, octopuses are thought to be one of the most behaviorally complex and advanced invertebrates. In particular, it appears Octopus bimaculoides has the same serotonin transporter gene as humans, which is known to serve as the “principle binding site of MDMA.”

Better known by its street names ecstasy and Molly, MDMA is a synthetic hallucinogenic drug that alters a person’s perception to feel a sense of euphoria. It does so by facilitating a rush of "happy" chemicals – serotonin, dopamine, and oxytocin – to the brain. In the case of the octopuses, the drug releases serotonin that is already present in the brain but is otherwise normally suppressed. However, the authors note that some of these behaviors may reflect an “adaptation of laboratory-raised animals” that could be different than those in the wild.

Despite evolutionary differences, the research shows that there are enough molecular similarities in the gene that transmits serotonin that both humans and octopuses have a similar experience with MDMA. Taking it one step further, octopuses may use similar pathways in the brain to be social at certain times, such as during mating.

This species of octopus is also the first to have its genome completely sequenced, and researchers say they are now in the process of sequencing two others that are closely related but display different types of behaviors. Comparing the genomes will hopefully help them further understand how social behaviors evolved.