However, ant colonies are not the only example in nature of decentralized intelligence. Evelyn Fox Keller, an american Physicist, spent much of her life studying the intersection between physics and biology and she was fascinated by the odd behavior of slime mold. The oddity of this system is that generally slime molds exists in the form of distinctive single cells each minding their own business but that in the right conditions they start aggregating forming almost a large organism. This mold cells aggregate, can crawl on the soil consuming dead leaves and branches that finds on its path. The question was: who gives the signal to the cells to start aggregating? For years biologists were looking for “peacemaker” cells, leader cells that tell their “comrades” what to do. This hypothesis fitted nicely in our way of thinking. Someone must tell other cells what to do. So for years we have been looking for these “general” cells in slime mold, the search was in vain. Although we could not find peacemaker cells, we realized that the mold cells respond to a molecule called acrasin (it’s a cyclic form of AMP) and its presence signalled the cells it was time to aggregate (Keller and Segel 1970). Yet, we still had no idea about who was responsible for the secretion of acrasin, because mold cells seemed to be interchangeable. At the end Keller developed an equation that demonstrated that mold cells did not need a leader, but each cell is able to modulate the release of acrasin depending of the conditions of the environment. Cells nearby would simply follow the acrasin trail and form clusters of cells, all releasing more acrasin and thus attracting more cells creating a positive feedback loop.

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