Octopuses on MDMA could provide clues to evolution of human social behaviour

21 Sep 2018

Octopus bimaculoides. Image: Tom Kleindinst/Johns Hopkins University

Scientists at Johns Hopkins University School of Medicine say they have discovered new insights into social behaviour by giving MDMA to octopuses.

Researchers claim to have found preliminary evidence of an evolutionary link between the social behaviours of octopuses and humans.

The research, published in the journal Current Biology, could lead to opportunities for the study of psychiatric drug therapies’ impact on many animals distantly related to humans. Due to how fast brains decay, we have little physical evidence to show how the human brain has evolved over time.

Examining the brain chemistry of octopuses

Neuroscientist Gul Dölen led the research, along with her colleague, Eric Edsinger. They wanted to examine whether the chemistry behind human social behaviours also exists in octopuses – creatures that are socially very different to humans.

Octopuses are intelligent animals but, unlike us, they do not have a localised brain with a cortex. Instead, they have a decentralised nervous system, which includes control centres for each tentacle. While humans are naturally social creatures, octopuses prefer a solitary existence and rarely socialise, with the exception of mating.

When humans take the drug MDMA, they become much more extroverted and are more interested in physical touch than usual. The scientists wondered if the drug would have a similar effect on octopuses, an animal that displays few commonalities with us.

They analysed the genome of the octopus and found that the animals also seem to have genes that code for serotonin transporters, which are proteins that move serotonin molecules into brain cells. MDMA changes how serotonin travels between brain cells, hence the feelings of affection and warmth experienced by those who take the drug.

A tank spiked with MDMA

The researchers then gave MDMA to seven Octopus bimaculoides creatures inside laboratory tanks. After this, the animals moved to a tank with three rooms to choose from: a central room, a room with a male octopus and a room with a toy.

Before the MDMA, octopuses avoided the male octopus, but spent much more time with the other creature after they had taken the drug. The octopuses also touched the male octopus in a manner that suggested gentle exploration, rather than aggression.

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

Dölen noted that the study does have limitations – seven animals is not a large enough sample size to accurately show how male and female octopuses react to MDMA. She plans to further test the changes she saw, including potentially blocking the serotonin transmitter before giving the drug. This would provide more validation that the effect of MDMA on serotonin transporters in the creatures was causing the changes in behaviour.

Ellen Tannam was a journalist with Silicon Republic, covering all manner of business and tech subjects