They discover that microRNAs play a fundamental role in the development of intelligence
So different, so similar… The last known common ancestor of humans and octopuses is a primitive, worm-like animal with minimal intelligence. From there, vertebrates and invertebrates evolved radically differently. While the former, in particular primates and other mammals developed large, complex brains with multiple cognitive abilities, the latter did not. With one exception: cephalopods.
The octopus never ceases to amaze scientists. It is the smartest invertebrate on the planet. He solves problems, learns from his mistakes, elaborates complex hunting strategies, has an extraordinary memory and a very high learning capacity, feels complex emotional pain, is very curious, recognizes people, shows playfulness, stable personality traits and self-awareness. Y sounds.
All these ‘talents’, for many centuries considered exclusively human, have to do with a highly complex nervous systemwhich has led to the case of the octopus in eight arms are capable of ‘thinking’ and to make decisions independently, and nine brains, one main in the head and eight secondary ones, one in each tentacle.
Scientists have long wondered why among animals lacking a backbone, only these mollusks could develop such a complex nervous system. Researchers at Max Delbrück and Dartmouth College in the United States believe they have found the reason.
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 an expansion of their repertoire of microRNAwhich are single-stranded RNAs with between 21 and 25 nucleotides.
prodigious intelligence
In an article published in ‘Science Advances’, an international team of researchers explains that octopuses possess a greatly expanded repertoire of microRNAs in their neural tissuewhich reflects developments similar to those that occurred in vertebrates.
“This is what connects us to the octopus,” comments Professor Nikolaus Rajewsky, Scientific Director of the Berlin Institute for Medical Systems Biology of the Max Delbrück Center and author of the paper. He ventures that the find probably means that microRNAs play a fundamental role in the development of complex brains. Perhaps also in that of humans.
Rajewsky’s interest in unraveling the mystery of the prodigious intelligence of octopuses arose in 2019, when he read a publication about genetic analyzes carried out on these animals.
Scientists had discovered that a large amount of RNA editing occurs in these cephalopods—a process that occurs regularly in human cells, which occurs when one base is substituted for another in an RNA molecule, changing its sequence and sometimes their function), which means they make extensive use of certain enzymes that can recode their RNA.
“This made me think that octopuses might have other RNA ‘tricks’ up his sleeve“, notes Rajewsky. Thus began a collaboration with the marine research station Stazione Zoologica Anton Dohrn in Naples, which sent him samples of 18 different types of tissue from dead octopuses.
The results of the analyzes were surprising: “Indeed, there was a lot of RNA editing, but not in areas that we think are of interest,” says Rajewsky. The most exciting discovery was, in fact, the spectacular expansion of a well-known group of RNA genes, the microRNAs.
“If you want to meet an alien, befriend an octopus”
Rajewsky and his team found in the octopus 42 new microRNA families, specifically in neural tissue and mainly in the brain. Since these genes were conserved during cephalopod evolution, the team concludes that they were “clearly beneficial to animals” and therefore “functionally important.”
Rajewsky has researched microRNAs for more than 20 years. The one found in octopuses is “the third largest expansion of microRNA families in the animal world and the largest outside of vertebrates“, highlights the study’s lead author, Grygoriy Zolotarov.
“To give an idea of the scale, oysters, which are also molluscs, have acquired only five new microRNA families since the last ancestors they shared with octopuses, while octopuses have acquired ninety. And oysters are not exactly known. for his intelligence,” adds Zolotarov.
From an evolutionary perspective, octopuses are unique among invertebrates. They have a central brain and a peripheral nervous system capable of acting independently. For example, if an octopus loses a tentacle, it remains sensitive to touch and can still move.
“They say that 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 form a European network that will enable further exchange.
Although the community is still small, Rajewsky emphasizes that interest in octopuses is growing worldwide, including among behavioral researchers. He considers it “fascinating” to analyze a form of intelligence that developed completely independently of humans.
Reference study: https://www.science.org/doi/10.1126/sciadv.add9938
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