What do human and octopus brains have in common?

The octopus never ceases to amaze scientists. This smartest invertebrate on the planet. He solves problems, learns from his mistakes, develops complex hunting strategies, has an outstanding memory and a very high learning capacity, senses complex emotional pain, is very curious.Recognizes people, shows playfulness, stable personality traits, and self-awareness. Y sounds.

All these “talents”, which for centuries were thought to belong only to humans, extremely complex nervous systemled to the octopus case. eight arms are capable of ‘thinking’ able to decide independently and nine brains, one primarily and eight secondary brains, one in each tentacle.

Scientists have long wondered why, among animals without a backbone, only these mollusks are able to develop such a complex nervous system. Researchers at Max Delbrück and Dartmouth College in the United States believe they have found why.

A team from the Max Delbrück Center for Molecular Medicine led by Nikolaus Rajewsky has shown that the evolution of octopus brains (and cephalopods in general) is linked to the expansion of their brain repertoire. microRNAThey are single-stranded RNAs of 21 to 25 nucleotides.

extraordinary intelligence

In an article published in the journal ‘Science Advances’, an international research team explains: Octopuses have a greatly expanded repertoire of microRNAs in their nervous tissues.reflecting developments similar to those occurring in vertebrates.

“This is what connects us to the octopus,” says Professor Nikolaus Rajewsky, Scientific Director of the Max Delbrück Center’s Institute for Medical Systems Biology in Berlin and author of the paper. I think finding probably means microRNAs play a fundamental role in the development of complex brains. Maybe in humans too.

Rajewsky’s interest in solving the mystery of the extraordinary intelligence of octopuses surfaced in 2019 when he read a publication on genetic analysis of these animals.

Scientists have discovered that a large amount of RNA editing occurs in these cephalopods – a process that occurs regularly in human cells, where one base in an RNA molecule is substituted for another, altered its sequence and sometimes its function). They make extensive use of certain enzymes that can recode their RNA.

“This made me think that octopuses might have other features. RNA ‘cheats’ arm“, says Rajewsky. Thus began a collaboration with the marine research station Stazione Zoologica Anton Dohrn in Naples, which sent him 18 different tissue samples from dead octopuses.

The results of the analyzes were surprising: “There’s actually been a lot of RNA editing, but not in the areas we thought we were interested in,” says Rajewsky. In fact, the most exciting discovery was the extraordinary expansion of a well-known set of RNA genes, microRNAs.

“If you want to meet an alien, befriend an octopus”

Rajewsky and team found in octopus 42 new families of microRNAs specifically in neural tissue and primarily in the brain. Because these genes were conserved during the evolution of cephalopods, the team concludes that they are “clearly beneficial to animals” and therefore “functionally important.”

Rajewsky has been researching microRNAs for over 20 years. found in octopuses”The third largest microRNA family in the animal world and the largest expansion outside of vertebrates“, underlines the lead author of the study, Grygoriy Zolotarov.

“For an idea of ​​scale, oysters, which are also mollusks, have acquired only five new microRNA families since their last common ancestor with octopuses, while octopuses have acquired ninety. And the intelligence of oysters is not fully known,” adds Zolotarov.

From an evolutionary point of view, octopuses are unique among invertebrates. They have a central brain and peripheral nervous systems that can act independently.. For example, if an octopus loses its tentacles, it remains sensitive to touch and can still move.

“they say If you want to meet an alien, go scuba diving and befriend an octopus‘ says Rajewsky, who now plans to join forces with other octopus researchers to create a European network that will enable more exchanges.

Although the community is still small, Rajewsky emphasizes: Interest in octopuses is growing worldwide, including by behavioral researchers. He finds it “fascinating” to analyze a form of intelligence that develops completely independently of humans.

Reference work: https://www.science.org/doi/10.1126/sciadv.add9938

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