Scientists have shown that the evolution of the octopus brain is linked to a spectacular expansion of its microRNA (miRNA) repertoire, a development similar to that of vertebrates, a group to which humans belong, as detailed in a published study. from Science magazine.
The scientific community has long wondered why such a complex nervous system could only develop in these types of marine animals called cephalopods, which include octopuses, squid and cuttlefish. The last known common ancestor between humans and cephalopods was a primitive, worm-like animal with minimal intelligence and simple eyes.
Cephalopods are known to be highly intelligent, have extraordinary memories, camouflage ability, great curiosity, and are even believed to have the ability to experience emotions and dream while sleeping. A recent study showed that female octopuses defended themselves against harassing males.
Ability to recode its RNA
To better understand their capabilities, the scientists looked at the RNA editing ability – extensive use of certain enzymes that can recode their RNA – of these marine animals: ‘This made me think that octopuses are not only good at RNA rolls up its sleeves,” said lead study author Nikolaus Rajewsky.
The results of analyzing 18 different types of tissue from dead octopuses were surprising, he recalled: A total of 42 new miRNA families were found, particularly in neural tissue and especially in the brain, a developmental feature similar to that of octopuses. animals. vertebrates.
“What unites us with octopuses”
“This is what unites us with octopuses,” said Nikolaus Rajewsky, author of the paper, who explains that this finding likely means that miRNAs play a vital role in the development of complex brains.
Instead of being translated into messenger RNA, which gives the instructions for protein production in the cell, these genes encode small pieces of RNA that bind to messenger RNA and thereby affect protein production.
Interest in these animals is growing
From an evolutionary perspective, octopuses are unique among invertebrates. The reason octopuses are the only ones to have developed such complex brain functions may lie in the fact that they use their arms for various purposes, as tools to open shells, for example.
The authors of the research are now planning to join forces with other octopus researchers to form a European network that will allow for more exchange between scientists. Although the community is currently small, interest in these animals is growing worldwide.