What is the simplest organism that was observed to learn: change its behavior permanently in response to some event/stimuli in a way that this change persists even if the event does not happen again?

  • 3
    $\begingroup$ the real problem is defining and testing learning. $\endgroup$ – John Jan 21 '17 at 1:44
  • $\begingroup$ Judging from the first source brought by Bryan Krause, the definition I had in mind was associative learning. $\endgroup$ – liori Jan 21 '17 at 18:28
  • $\begingroup$ which may be possible for even a single celled organism. Bryan Krause provided a good link to possible associative learning in amoebae. $\endgroup$ – John Jan 21 '17 at 20:31

I don't know if it is definitively the simplest, but the simplest organism with a nervous system that has been studied extensively is probably C. elegans, which is definitely able to learn.

Some basic learning abilities have also been shown in amoebae.


  • Ardiel, E. L., & Rankin, C. H. (2010). An elegant mind: learning and memory in Caenorhabditis elegans. Learning & Memory, 17(4), 191-201.

  • Saigusa, T., Tero, A., Nakagaki, T., & Kuramoto, Y. (2008). Amoebae
    anticipate periodic events. Physical review letters, 100(1), 018101.


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