Barely-alive creatures, such as the slime mold at right, are able to produce “memories” — they just store them in their physical surroundings rather than a brain, Ars Technica has the latest news on the secret lives of simple beings:
Is it possible to know where you’ve been when you don’t have a brain? Depending on your definition of “know,” the answer may be yes. Researchers have shown that the slime mold, an organism without anything that resembles a nervous system (or, for that matter, individual cells), is capable of impressive feats of navigation. It can even link food sources in optimally spaced networks. Now, researchers have shown it’s capable of filling its environment with indications of where it has already searched for food, allowing it to “remember” its past efforts and focus its attention on routes it hasn’t explored.
In the course of studying the slime mold, some researchers noticed that the slime mold would avoid any areas covered in slime. Based on this finding, the authors hypothesized that the mold “uses its [the slime's] presence as an externalized spatial memory system to recognize and avoid areas it has already explored.” So, they came up with a test that, in their words, “challenged our slime mold.”