In the film The Wizard of Oz, the scarecrow famously pines for a brain but eventually comes to realize that he already possesses all the smarts he needs. Similarly, acellular slime molds—strange, gelatinous organisms that consist of a single cell with billions of nuclei—lack a brain yet sometimes act like far more sophisticated creatures.
“We can’t say that slime molds have personalities, because people would be very upset,” says Audrey Dussutour, a behavioral biologist at Toulouse University III–Paul Sabatier in France. But “these giant cells have quite complex behaviors and display different ways of making a decision.”
Dussutour and her colleagues were interested in studying how three strains of a particular slime mold species handle trade-offs between speed and accuracy when trying to find food. After presenting strains native to Japan, Australia and the U.S. with food sources of varying quality, the researchers observed which ones the organisms chose to engulf and consume. The Japanese strain acted quickest, randomly selecting whatever food it found. The Australian strain took longest but typically chose the best food. The American slime mold decided more slowly than the Japanese strain but faster than the Australian one and also opted for the highest-quality grub.
The speedy Japanese slime mold would likely have an edge in places where resources are scarce and competition is high, making any food better than no food, the researchers reported in February in the Proceedings of the Royal Society B. The Australian strain might be better suited to resource-rich environments in which slow decision-making would maximize nutritional benefits. The American strain would probably thrive in both environments.
These findings add an ecological spin to the growing body of work on decision-making capabilities in the simplest organisms, says James Marshall, a theoretical and computational biologist at the University of Sheffield in England, who was not involved in the study. “Taking longer over making the right decision can make sense in isolation, but when competing with others, being quick but inaccurate can be better.”