Study
Maze-solving by an amoeboid organism
Nakagaki, Toshiyuki; Yamada, Hiroyasu; Tóth, Ágota
Nature, 2000
A plasmodium of Physarum polycephalum was spread through an agar maze so that it occupied every corridor, then food was placed at two exits. The organism’s subsequent distribution of tubes was recorded.
- Studied in
- Physarum polycephalum
- Sample size
- repeated maze trials with a single plasmodium per trial
The plasmodium withdrew from dead ends and retained a thick connecting tube along the shortest path between the two food sources, within a few hours.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
The organism displays a primitive form of intelligence: it finds the minimum-length solution connecting the food sources.
How NatureHQ reads it
The result is real and the word "intelligence" in the paper is doing a lot of work. The mechanism is local: tubes carrying more flow thicken and tubes carrying less are reabsorbed, which converges on short paths without anything representing the maze or choosing a route. That is a more interesting finding than intelligence would be, because it shows how little machinery a good solution needs — and it is precisely the part that popular retellings drop.
- A single species in a two-exit maze on agar; not a general problem-solving assay.
- The organism starts occupying the entire maze, so it does not search — it prunes.
- No comparison with the many physical systems that also find short paths by flow reinforcement.
A single cell in a maze
Can an organism with no nervous system find the shortest path between two points?
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Published by: Nature PortfolioPublished in a Nature Portfolio journal.
This reference was resolved automatically against Crossref on 2026-08-11.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-10.