Squid are clever creatures with ingenious abilities, and now scientists have uncovered a clue that may partially explain the cephalopod’s remarkable intelligence: Its genes have a genetic quirk also found in humans, a new study finds.
The clues scientists have uncovered are called “jumping genes” or transposons, and they make up 45% of the human genome. Jumping genes are short sequences of DNS with the ability to copy and paste or cut and paste themselves elsewhere in the genome, and have been implicated in the evolution of genomes in several species. Genetic sequencing recently revealed that two species of squid – Octopus vulgaris and Octopus bimaculoides — also have genomes filled with transposons, according to a study published May 18 in the journal BMC biology.
In both humans and squid, most transposons are dormant, either silenced due to mutations or prevented from replicating by cellular defenses, the study authors reported. But one type of transposon in humans known as Long Interspersed Nuclear Elements, or LINE, can still be active. Evidence from previous studies suggests that LINE jump genes are tightly regulated by the Brainbut are still important for learning (opens in new tab) and memory formation in the hippocampus.
As scientists delved deeper into octopus jump genes, which could freely copy and paste the genome, they discovered transposons from the LINE family. This element was active in the vertical lobe of the octopus – a brain section in octopuses that is crucial for learning and functionally analogous to the human hippocampus, Graziano Fiorito, study co-author and biologist at the Zoological Station Anton Dohrn (SZAD) in Naples , Italy , said Live Science.
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In the new study, the researchers measured the transcription of an octopus transposon RNA and translation too protein, and they found significant activity in areas of the brain related to behavioral plasticity — how organisms change their behavior in response to different stimuli. “We were very happy because this is a kind of proof,” said Giovanna Ponte, co-author of the study, a researcher in SZAD’s Department of Biology and Evolution of Marine Organisms.
Although squid are not closely related to backbone animals, they still exhibit behavioral and neuronal plasticity similar to that of vertebrates, Fiorito added. “These animals, like mammals, have the ability to continuously adapt and problem-solve,” and this evidence suggests the similarity might arise at the genetic level, he said.
Not only do these results link jumping genes to octopus intelligence, they also suggest that LINE transposons can do more than just jump around. Rather, they play some role in cognitive processing, the authors suggested in a expression. Because jumping genes are shared by humans and squid, they could be good candidates for future research on intelligence and its evolution and variation between individuals within a species, according to the study.
However, since octopuses are fairly distant from humans on the tree of life, it’s possible that active LINE transposons in the two groups are an example of this convergent evolution. This means their contribution to intelligence evolved separately in the two lineages and did not come from a common ancestor, the scientists reported.
Originally published on Live Science.