Octopuses and their relatives owe part of their remarkable intelligence to an ancient reshuffling of their DNA, according to a new study from the University of Vienna published in Nature Communications. The researchers reconstructed the three-dimensional folding of the genome in octopuses, squid, and cuttlefish and compared it with gene activity. They found that hundreds of millions of years ago, large sections of genetic material were rearranged, bringing previously separated regions into contact and creating new opportunities for genes to influence one another.
Lead author Dr. Thea Rogers said the genome is not just a sequence of genes but a folded three-dimensional structure, and understanding how that structure evolves is key to understanding biological complexity. The team describes the gradual buildup of interconnected regulatory interactions as 'regulatory entanglement.' This process may allow new traits to emerge without disrupting essential functions.
The study also found that large chromatin domains stayed stable over evolutionary time, while smaller chromatin loops varied between species, tissues, and developmental stages. Many of these flexible loops appeared near genes involved in nervous system development, suggesting they may have helped drive the evolution of cephalopod intelligence. The authors caution that the results do not prove these DNA changes caused the nervous system evolution, but they point to genome architecture as an active player in evolution.