Last common ancestor between cephalopods and Homo sapiens. Studies highlighted and conducted by Peter Godfrey Smith point to a complex intelligence in the modern octopus, and likely even self-awareness. This poses a dilemma: either self-awareness evolved independently at least two or three times (us, octopuses, crabs, etc.), or it evolved only once, but long ago, before the emergence of cephalopods. The last common ancestor between cephalopods and Homo sapiens dates back 600 million years. The octopus’s nervous system is very different from ours, essentially having a central brain (with two hemispheres and no corpus callosum connecting them above) and eight large groups of neurons distributed across each tentacle. It’s unknown how the interaction between these 8+1 “brains” works, but one hypothesis is that there are different circumstances where different modalities are used (independence of the tentacles or central control of the brain in the octopus’s “head”). Octopuses also possess some characteristics found in other species (including Homo sapiens), such as REM sleep.
