Octopuses given ecstasy reveal link to evolution of human behaviours

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Notoriously antisocial octopuses have been made to mingle after scientists fed them small doses of ecstasy.

Researchers found that the mood altering substance favoured by ravers changed their behaviour in a similar way to human partygoers.

The experiment, which left the creatures hugging their cages, could open a window into treatments for depression and other mental disorders, experts say.

It also suggests an evolutionary link between the social behaviours of the sea creatures and humans – despite the species being estranged by more than 500 million years apart on the ‘tree of life’.

The finding is remarkable since the last common ancestor shared by human beings and octopuses would have been a wormlike marine creature, experts say.

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Notoriously antisocial octopuses have been made to mingle after scientists fed them the party drug ecstasy. Researchers found that the mood altering substance favoured by ravers changed their behaviour in a similar way to partygoers  

Notoriously antisocial octopuses have been made to mingle after scientists fed them the party drug ecstasy. Researchers found that the mood altering substance favoured by ravers changed their behaviour in a similar way to partygoers  

WHAT DID THE TEST INVOLVE? 

Experts designed an experiment in which four male and female octopuses were put in a tank with three equal-sized chambers

In one was a plastic action figure, another a second octopus and the last was left empty.

The animals were monitored for 30 minutes and the two males focused their attentions only on the females – while shunning other males.

Then, after waiting several hours, they soaked the four male and female octopuses in an ecstasy bath for 10 minutes which they absorbed through their gills, before returning them to the partitioned tank.

This time, there was a clear difference. The octopuses were ‘high’, spending much more time with other octopuses, of both sexes, than before.

All four tended to spend more time in the chamber where a male octopus was caged than the other two chambers.

This is markedly unusual behaviour for the creatures, who normally stick to themselves.

Neuroscientists at Johns Hopkins University, Baltimore, Maryland, say it is fascinating to see ecstasy, the nickname for psychoactive drug MDMA works on octopuses exactly the same way it does on people.

The gelatinous invertebrates also have a well earned reputation for escaping from their tank, eating other animals’ food, eluding caretakers and sneaking around.

But most are anti social and avoid interactions, including with other octopuses. 

Despite this, experts suspected there may be a link between the genetics that guide social behaviour in them and humans.

Study lead Professor Gul Dolen said: ‘The brains of octopuses are more similar to those of snails than humans.

‘But our studies add to evidence they can exhibit some of the same behaviours we can.

‘What our studies suggest is certain brain chemicals, or neurotransmitters, that send signals between neurons required for these social behaviours are evolutionarily conserved.’

The experiments analysed the genome of a type of octopus particularly unfriendly towards its peers, then tested its reactions after being given the drug. 

Professor Dolen said octopuses are well known for their intelligence. They can trick prey to come into their clutches, and it is believed they also learn by observation.

Like humans, they are thought to have episodic memory which is very rare in the animal kingdom. This is the recollection of autobiographical events, past personal experiences that occurred at a particular time and place.

One place to look was in the genomics that guide neurotransmitters, the signals brain cells pass between each other to communicate.

So he teamed up with Dr Eric Edsinger at the Marine Biological Laboratory in Woods Hole, Massachusetts, who recently mapped the full DNA of the California two spot octopus, or Octopus bimaculoides.

Like most octopuses, this colour changing cephalopod likes to be alone most of the time, unless it is trying to mate.

But when given ecstasy, known for boosting emotional empathy and prosocial behaviour in human, these octopuses seemed to want to hang out with each other – even if they weren’t trying to find a mate.

The experiment, which left the creatures hugging their cages, could open a window into treatments for depression and other mental disorders, experts say.  Ecstasy (pictured), known chemically as MDMA, has been used by clubbers for decades (stock images)

The experiment, which left the creatures hugging their cages, could open a window into treatments for depression and other mental disorders, experts say.  Ecstasy (pictured), known chemically as MDMA, has been used by clubbers for decades (stock images)

WHAT IS MDMA?

Ecstasy, known chemically as MDMA or molly, has been used by clubbers for decades due to its effects in helping keep people awake.

It can come in the form of various pills and often takes about 30 minutes for its long-lasting effects to kick in, which can include feelings of love.

In the UK, possession of any form of ecstasy – considered a Class A drug – comes with a potential jail term of up to seven years. In the US, the jail term can be as severe as 40 years in some states.

Drug campaigners warn the biggest of taking MDMA revolves around the fact that many users are unaware of what is in the substance they are taking.

It can include other drugs, such as PMA, which can be fatal in lower doses than MDMA itself.

The Office for National Statistics recorded an eight fold increase in ecstasy deaths last year compared to 5 years ago.

The statistics showed that 63 people died from taking MDMA in 2016 – significantly higher than that of the record low in 2010 of eight deaths.

Specifically, the researchers found octopuses and humans had nearly identical systems for carrying the feelgood chemical serotonin through the brain.

Serotonin is a well-known regulator of mood and closely linked to certain kinds of depression.

Ecstasy boosts mood by binding to this pathway so they decided to see how octopuses react to the drug – which makes humans, mice and other vertebrates more sociable.

Professor Dolen designed an experiment in which four male and female octopuses were put in a tank with three equal-sized chambers

In one was a plastic action figure, another a second octopus and the last was left empty.

The animals were monitored for 30 minutes and the two males focused their attentions only on the females – while shunning other males.

Then, after waiting several hours, they soaked the four male and female octopuses in an ecstasy bath for 10 minutes which they absorbed through their gills, before returning them to the partitioned tank.

This time, there was a clear difference. The octopuses were ‘high’, spending much more time with other octopuses, of both sexes, than before.

All four tended to spend more time in the chamber where a male octopus was caged than the other two chambers.

This is markedly unusual behaviour for the creatures, who normally stick to themselves. Social behaviour that is normally suppressed was being expressed. 

Professor Dolen said: ‘It’s not just quantitatively more time, but qualitative. They tended to hug the cage and put their mouth parts on the cage.

The findings suggests an evolutionary link between the social behaviours of the sea creatures and humans - despite the species being 500 million years apart on the 'tree of life'. Ravers favour ecstasy thanks to its feelings of euphoria and energy (stock image)

The findings suggests an evolutionary link between the social behaviours of the sea creatures and humans – despite the species being 500 million years apart on the ‘tree of life’. Ravers favour ecstasy thanks to its feelings of euphoria and energy (stock image)

‘This is very similar to how humans react to MDMA – they touch each other frequently.’

Under normal conditions, without MDMA, five male and female octopuses avoided only male, caged octopuses.

Professor Dolen said the experiments suggest the brain circuits guiding social behaviour in are present in normal conditions, but may be suppressed by natural or other circumstances.

He added the results are preliminary but if replicated in further studies octopuses may be used as models for brain research.

When people take ecstasy, a rush of serotonin and other chemicals linked to mood including dopamine and oxytocin produce feelings of emotional closeness and euphoria.

This makes them more interested than they would normally be in connecting and sharing with others.

Professor Dolen said: ‘Despite anatomical differences between octopus and human brain, we’ve shown that there are molecular similarities in the serotonin transporter gene,’

‘These molecular similarities are sufficient to enable MDMA to induce prosocial behaviours in octopuses.’

The researchers are now in the process of sequencing the genomes of two other species of octopus, which are closely related but differ in their behaviours.

By comparing them, they hope to gain more insight into the evolution of social behaviour. 

The research may open the door to accurately studying the impact of psychiatric drug therapies in many animals distantly related to people. 

The full findings were published in the journal published in Current Biology.



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