by Elio The practice of agriculture is not limited to humans: ants, termites, and snails all grow fungi, and who knows who else do something similar. But not many have claimed that such activities are to be found among simpler organisms. Now we have a report that slime molds have also gone down the road to agriculture. Dictyostelium discoideum, the best studied of the cellular slime molds, is a social amoeba that thrives by grazing on bacteria. Given ample bacterial food, these organisms grow as single cells. When food becomes scarce, they aggregate into pretty, differentiated fruiting bodies (called sorus, plural sori) consisting of a round mass of spores held up by a stalk. The spores eventually become dispersed, to repeat the cycle at a new site. The entire epic can be viewed in a dramatic documentary available here. (This movie is narrated in German, giving you the opportunity to hone your skills in that language.) What is new here is that about one third of 35 clones of this species collected in the wild do something extra, namely they carry bacteria with them as they differentiate. They even include them within their sori. Once released, the spores have the ready opportunity to enjoy the source of food providently supplied for them. But non-farmers eat up all the available food before differentiating, whereas the farmers leave about half of the bacteria uneaten. It’s a little bit like humans not eating a whole grain harvest, but carrying some along when migrating to provide seeds for future sowing.