The Guardian (Long Read) ·For the curious
‘This is Dangerous’: Slime Moulds and the Bitter Debate Over the Nature of Intelligence
by Samanth Subramanian
Published 2026-09-08 04:00:27+00:00
If a single cell can solve a maze, does a mind really need a brain?
0:00 / 37:42 · Narrator Charon
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Context
A brainless, yellow organism sits at the centre of a bitter scientific fight in this piece from 8 September 2026. A slime mould can solve a maze and map a railway network—all without a single neuron. But the real tension is not about what the organism can do, but what biologists are willing to call it. The resulting debate forces a question that makes purists deeply uncomfortable: what if a single cell can actually think?
Show notes
A report on the scientific dispute over whether brainless organisms like slime moulds possess intelligence. Drawing on experiments that show single cells solving mazes and mapping rail networks, the reporting outlines a growing divide in biology. It contrasts scientists who believe cognition requires a nervous system with a new group of researchers arguing that memory and decision-making are basic properties of all living things.