If you've ever wondered what would happen if you gave an octopus a strong dose of ecstasy then wonder no more. A couple of intrepid researchers have recently revealed the results of a compelling set of experiments finding that social behavior can be triggered in a particularly asocial species of octopus through exposure to MDMA.

Octopus bimaculoides, also known as the California two-spot octopus, is an incredibly intelligent invertebrate. Over 500 million years ago human and octopus lineages diverged, resulting in highly unique differences in brain organization.

Recent sequencing of the octopus genome revealed a fascinating similarity to humans in certain regions that signal the binding of the neurotransmitter serotonin. This observation proved interesting to researchers Gui Dölen and Eric Edsinger, as serotonin is an important mood-regulating compound, as well as being implicated in the regulation of social behavior.

Octopuses, on the other hand, are infamously solitary, generally only interacting socially during mating periods. This led the research duo to wonder whether the drug MDMA, known to trigger an increase in the neurotransmitter serotonin, would affect the social behavior of octopuses.

The first step in the research was to figure out a way to experimentally quantify the social behavior of an octopus. To do this the researchers created a three-chamber aquarium. On one side a novel object was placed in a cage, and on the other side was a female or male caged octopus. The idea was that when an octopus was placed in the central chamber it could freely roam between either the object or the other octopus, allowing scientists to quantify its social approach behavior. This approach was adapted from a set-up routinely used to study the social behavior of rodents.

At this stage the experiment was already delivering novel results, revealing that both female and male octopuses avoided spending time in the social chamber with another octopus only when that caged octopus was male. This fascinating revelation suggests the species displays a significant preference in social interactions with females versus males.

But what then happens after the octopuses were given MDMA?

To dose the octopuses they were submerged for 10 minutes in an MDMA solution, allowing the animals to absorb the drug through its gills. After a 20-minute rinse with saline the octopuses were returned to the three-chamber set-up.

The MDMA-dosed octopuses displayed significantly different behaviors, with a notable increase in the time spent inside the chamber with the other octopus. Most stark was the increase in social contact when a male octopus was placed in the social chamber. Previously, the test octopus would avoid the social chamber particularly if a male was inside, but after MDMA the animals spent a great deal more time interacting with one another.

"It's not just quantitatively more time, but qualitative," says Dölen. "They tended to hug the cage and put their mouth parts on the cage. This is very similar to how humans react to MDMA; they touch each other frequently."

The implications of this small yet exciting study suggest that, despite octopuses evolving incredibly unique brains and behaviors, they still may be fundamentally socially regulated by the same neurotransmitters as humans.

"What our studies suggest is that certain brain chemicals, or neurotransmitters, that send signals between neurons required for these social behaviors are evolutionarily conserved," says Dölen.

It's an incredibly intriguing hypothesis, that serotonergic signaling is an ancient social modulator present in the brains of animals that are significantly different from us. Not everyone is convinced though. Speaking to the Atlantic, Jennifer Mather from the University of Lethbridge suggests the observations noted in this study don't explicitly connect MDMA with increased sociability in the animals. Instead, Mather points out the chemical intervention may simply be disrupting the animal's general ability to sense others, resulting in more tactile attempts to understand its surroundings.

And to be honest, it is tempting to interpret these observations from an anthropomorphic perspective. As the social behavior of octopuses is still incredibly understudied it is tempting to conclude similarities in behavior with humans on MDMA. Speaking to Gizmodo, Dölen does anecdotally describe the animals as acting like they consumed ecstasy, swimming around "doing water ballet."

Dölen does readily admit this is not scientific observation, but it raises some provocative questions. Despite hundreds of millions of years of independent evolution, it is exciting to think that the structure of an intelligent brain still relies on similar neurotransmitter activity to modulate social activity.

The new study was published in the journal Current Biology.