Tony Soprano and social amoebae have one thing in common: They only trust family. When things get tough, the single-celled organisms gang up with their closest relatives like any cutthroat mobster would, a strategy that may protect them from swindlers, new research shows. Scientists say the slimy cooperation may shed light on how some of the earliest social behavior first evolved.
The social amoeba Dictyostelium discoideum usually lives alone, dining on bacteria in the forest soil. When food becomes scarce, tens of thousands of neighboring amoebae meld into a blob–about a third the length of an eyelash–that slithers much farther than any amoeba could on its own. When the slug reaches a warm, sunlit locale, the aggregate transforms into a fruiting body: About 20% of amoebae sacrifice themselves to form a rigid stalk, hoisting their comrades upward as a ball of spores. These lucky amoebae hitch rides on the fur of passing mammals to reach greener pastures. The martyrs of the stalk wither and die.
The strategy seems ripe for cheaters. After all, amoebae that shirk their stalk duty have a better chance of survival–and are more likely to pass their deceitful ways on to the next generation. Yet cheaters haven't overtaken the species, so something must be keeping them honest. A team led by biologists Elizabeth Ostrowski of Rice University and Mariko Katoh of Baylor College of Medicine, both in Houston, Texas, wondered whether that something might be nepotism. In certain insect species, for example, workers “sacrifice” themselves for the good of their relatives so that some of their shared genes are passed on.
More here. (Do watch the fascinating video on this linkalso.)