This Single-Celled Creature Is Weirdly Smart

Stentor roeseli composite image. This work has been released into the public domain by its author, Protist Image Database

Scientists say they’ve observed what they’re calling signs of complex decisionmaking in a single-celled organism, breathing new life into a theory that was laughed off over a century ago.

Dan Robitzski |

The aquatic creature, Stentor roeseli, responds differently over time to the same stimulus, which ScienceAlert reports is evidence that the critter can make decisions — or at least do whatever the single-celled equivalent of changing one’s mind might be. It’s not quite accurate to say a creature without any sort of nervous system is actively thinking, but the discovery challenges many of scientists’ assumptions about animal intelligence.

Poke Test

Similar single-celled organisms will gradually respond less and less to repeated stimuli. Stentor roeseli, however, will first bend away from the source of the stimulus — but later change tactics and flap its cilia in defense, contract, or float away, according to research published Thursday in Current Biology.

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