Scientists speculate whether octopuses are able to dream like us
Scientists have discovered that octopuses and other cephalopods have alternating sleep states – and perhaps even dream – like us.
It’s hard not to wonder whether a twitching, colour-changing sleeping octopus is dreaming.
It’s difficult enough to know what’s going on inside the head of a fellow human, let alone a member of a different species – especially one that doesn’t even have a backbone. But new research on the brain function of sleeping octopuses reveals striking similarities with ourselves and raises the tantalising possibility that they dream like we do, too.
It’s no secret that cephalopods – octopus, cuttlefish and squid – are remarkably intelligent by molluscan standards and are a match even for many a vertebrate.
“They have quite special learning abilities, including spatial and social learning, as well as problem-solving capabilities,” says Sidarta Ribeiro, who led the research at Brazil’s Federal University of Rio Grande do Norte. And it turns out that those very learning abilities may be linked to a mode of sleeping that is uncannily similar to our own. Ribeiro’s team have found that octopuses, just like us, exhibit two phases of sleep – one ‘quiet’ and one ‘active’. During the active phases, which occur in bursts of about 40 seconds, they twitch their muscles, move their eyes and change the texture and colour of their skin (see video link below).
Ribeiro says it’s well established that, in mammals, alternation between quiet and active sleep enables the consolidation of memories.
“It is tempting to speculate that similar mechanisms are at play in the octopus,” he says. Quiet and active sleep “may reflect the evolutionary pressure to process a heavy load of newly acquired memories in need of integration across distant brain regions”.
It’s hard not to wonder whether a twitching, colourchanging, sleeping octopus is experiencing something akin to a dream.
“It is not possible to affirm that,” says Ribeiro, “but our results suggest that during active sleep, the octopus experiences a state analogous to REM [Rapid Eye Movement] sleep, which is the state when humans dream the most.” An octopus generally changes colour for camouflage, but when sleeping it bears little relationship to the surroundings, says Ribeiro: “We can infer that the colour changes result from brain activity that is independent of the external stimuli.”