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""Experiments with amoebae that usually live as individuals but must also join with others to form multicellular bodies to complete their life cycles showed that cooperation depends on kinship. If amoebae occur in well-mixed cosmopolitan groups, then cheaters will always be able to thrive by freeloading on their cooperative neighbors. But if groups derive from a single cell, cheaters will usually occur in all-cheater groups and will have no cooperators to exploit. A multicellular body like the human body is an incredibly cooperative thing," Queller says, "and sociobiologists have learned that really cooperative things are hard to evolve because of the potential for cheating. "It's the single-cell bottleneck that generates high relatedness among the cells that, in turn, allows them to cooperate, " he says."

"Oxygen may not be the staple of modern complex life that scientists once thought. Until now, the only life forms known to live exclusively in anoxic conditions were viruses, bacteria and Archaea. But in a new study, scientists have discovered three new multicellular marine species that appear to have never lived in aerobic conditions, and never metabolized oxygen. "