IT鈥橲 not just human societies that deem some of their members to be
鈥渦ntouchable鈥�. Colonies of Atta cephalotes ants contain a group of
shunned workers that toil in the colony鈥檚 rubbish dump, researchers at the
University of Sheffield have found.
The dumps are riddled with disease-causing mites and nematodes, so many of
the garbage workers survive only half as long as their clean-living siblings.
But any ants trying to leave the dump are hustled back by the workers in the
tunnel outside.
鈥淭he aggressive behaviour is extreme. Workers contaminated with garbage may
be ripped to pieces, with legs and heads severed,鈥� says graduate student Adam
Hart. The study will appear in the journal Behavioral Ecology and
Sociobiology.
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