Scientific American An Octopus Could Be the Next Model Organism Big-brained cephalopods could shine light on the evolution and neurobiology of intelligence, complexity, and more—and inspire medical and technological breakthroughs species pictured here). Credit: Joel Sartore Advertisement Humans are more closely related to dinosaurs than they are to octopuses. Our lineage split from that of cephalopods—the spineless class that includes octopuses, squids and cuttlefish—half a billion years ago. Octopus brains lack any of the major anatomical features of vertebrate brains, and most of the animals' neurons are distributed across their arms rather than in their head. Yet octopuses are extremely intelligent, with a larger brain for their body size than all animals except birds and mammals. They are capable of high-order cognitive behaviors, including tool use and problem-solving, even figuring out how to unscrew jar lids to access food. Increasingly, some researchers are suggesting octopuses' combination of smarts and sheer difference from humans could make them an ideal model for inferring common rules governing complex brain function, in addition to revealing novel neurological workarounds cephalopods have evolved.