Dictyostelium discoideum amoebae are normally independent creatures, but hunger makes them social. Starvation can trigger tens of thousands of the amoebae to aggregate into a mobile slug that eventually differentiates into a fruiting body (seen in the picture above) that holds living spores aloft on stalks made of dead amoebae.
About 20 percent of the amoebae sacrifice themselves to form the stalk that lifts living spores up and helps them disperse, carried off by insects.
This clear separation into altruists (dead stalk cells) and beneficiaries (living spore cells) is reminiscent of an ant colony where the sterile workers assist their queen in reproducing.
