Octopuses on ecstasy became more friendly in a new study

It may seem like octopus and humans have nothing in common.

After all, almost 500 million years ago, octopus separated from humans on the evolutionary family tree and, with their eight arms, three hearts and sharp bill, they did not look much like primates. The venomous cephalopods possess an extraordinarily large brain, whose neurons, unlike humans, are distributed mainly in their arms, comprising a unique complex nervous system. Octopuses also possess strange and extraterrestrial abilities: they can taste what they're touching, paralyze their prey with saliva, change skin color to use blind enemies and camouflaged with jets of water. ink.

But the common point between octopus and humans is intelligence.

Thinking of being among the first intelligent creatures on the planet, it was observed that octopuses were playing, navigating in labyrinths and even collecting coconut shells to build a shelter, an example of the use of tools. They also display an incredible ability to escape human captivity. In 2016, a young octopus from the National Aquarium of New Zealand was able to sneak into a tiny hole at the top of its tank, fall to the ground, descend a long escape hose and dive into the ocean, never seen by the staff of the aquarium. again.

A crucial difference

Despite this, many scientists have long believed that octopuses and other invertebrates do not have the neural requirements to feel emotions or social behaviors, as do mammals.

However, a new study published in the journal Current Biology challenges this long-standing presumption by showing that the administration of MDMA to octopus seems to elicit from them a social behavior, suggesting that the architecture to experience such phenomena goes back further in the history of evolution than previously thought.

The three-zone tank used in the experiment. Cage with toy on the left, octopus cage on the right.

For the study, the researchers developed an experiment in which they placed a two-point California octopus in a tank containing three pieces separated by two walls with slots. The middle piece was empty, but the two pieces on each side contained either a "new toy object" (a Stormtroopers figure) in a cage or another octopus in a cage, and the uncredged octopus was free to spend time in the room it rained.

The five octopuses that completed this part of the experiment spent much more time in the room with the toy, although the male and female octopuses tentatively explore the other room when there was a female in the cage.

The researchers then conducted this experiment again, but this time each octopus was bathed in water containing MDMA before entering the three-zone reservoir. Contrary to what happened before, the octopus of MDMA seemed much more interested in the octopus piece, sometimes touching it in an exploratory way, instead of the piece containing a toy without a case.

An "eight-armed" hug

Gül Dölen, Ph.D., assistant professor of neuroscience at Johns Hopkins University and co-author of the study, said: reverse it was like watching an "eight-armed hug".

"They were very cowardly," says Dölen. "They just kissed with multiple arms."

It is impossible to know what octopus lived, but Dölen offered his own personal observation (as anecdotal, unscientific GizmodoOctopuses have acted like humans when they are ecstatic.

In high doses, the octopuses exhaled intensely and became white. But at a lower dose, the octopus seemed to be more typical of a psychedelic: there was a lot of interest in minor sounds and odors, another spent time flipping and an octopus "looked like a ballet" . swim with his arms extended.

In humans, MDMA acts primarily on the brain by stimulating the activity of the neurotransmitter serotonin. California's two-point octopus also has a serotonin transporter to which MDMA can bind. However, researchers did not know if this ancient feature was active in octopus.

"We had to check the genome to make sure that the genes encoding the serotonin transporter, the protein to which MDMA binds, remained a binding site in the octopus, even though the evolution time was over." said Dölen. reverse.

"We did a phylogenetic mapping of the trees and found that even though their serotonin transporter gene is 50-60% similar to that of humans, the gene was still conserved, so MDMA would have a place in the brain. could encode sociality as in the human brain. "

Familiar behavior in strange brain structures

The idea that octopus behavior could be regulated by serotonin, which largely controls human emotions, is particularly interesting because of the difference between creatures and humans.

"It was such an amazing article, with a completely unexpected and almost unbelievable result," said Judit Pungor, a postdoctoral researcher at the University of Oregon not involved in this study. Gizmodo. "To think that an animal whose brain has evolved completely independently of ours reacts behaviorally in the same way as we do with a drug is absolutely incredible."

Admittedly, it is unclear why octopuses are "open" on MDMA. In addition to the fact that the study is limited by the size of the sample, it is possible that the octopus is more likely to touch the other octopus because the drug makes them more interested in touching themselves in general, not necessarily to touch others.

However, Dölen said the results suggest that molecular and cellular genetic information, not necessarily anatomical data, determines whether animals develop social behavior.

"Octopuses do not have the same parts of the brain that we think are important for social behavior, a region called the nucleus accumbens," Dölen said. reverse. "We argue that brain regions do not matter – what matters is that they own the molecules, neurotransmitters, and certain neuron configurations." They have the carrier of serotonin and that's enough. "