More than 100 years ago, a zoologist by the name of Herbert Spencer Jennings described surprisingly complex and varied avoidance behaviors in a single-celled freshwater protist known as Stentor ...

There are three domains of life: bacteria, archaea, and eukarya. Eukaryotic cells are more complex than bacteria, but there are single-celled eukaryotes, and those that don't fit into any other ...

A trumpet-shaped, single-celled organism seems able to predict one thing will follow another, hinting that such associative learning emerged long before multicellular nervous systems ...

Much more difficult is learning to connect different types of stimuli or events, and predicting that one is linked to another. Such associative learning was most famously demonstrated when Ivan Pavlov ...