By Susan Milius
Birds, bees and educated fleas actually don’t do it. But a social amoeba turns out to practice a simple form of agriculture in the form of bacterial husbandry.
Dictyostelium discoideum, aka the slime mold, is the latest member in a small club of species known to practice farming. It’s not fancy. But 13 out of 35 wild strains of the tiny soil-dwelling creature routinely stop grazing on their bacterial food while there’s still some left, reports Debra A. Brock of Rice University in Houston. The social amoebas then mix uneaten bacteria into reproductive structures that release spores complete with starter kits for planting a new food patch, Brock and her colleagues report in the Jan. 20 Nature.
There’s no evidence so far that the social amoebas tend a bacterial crop once it starts growing, notes evolutionary geneticist Duur Aanen of Wageningen University in the Netherlands, who wasn’t part of the research. Yet, he says, “the example described in this paper really fulfills the definition of farming: carrying, seeding and prudent harvesting of food.”