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BOB HIRSHON (host):
How ants prove they\’re alive. I\’m Bob Hirshon and this is Science Update.
Like many social insects, Argentinian ants operate a sort of morgue: they pile their dead outside the nest, to reduce the spread of disease. Now, scientists have figured out how they tell truly dead nest-mates from merely sluggish ones. Dong-Hwan Choe and his colleagues at the University of California, Riverside, found that when ants that had died just a few minutes ago were dropped in a nest, the other ants left them alone.
DONG-HWAN CHOE (University of California, Riverside):
But if I put one-hour-dead ants into the nest, they promptly carried them away.
Further tests showed that the ants identified their dead by chemicals called triglycerides. They\’re actually found on both living and dead ants, but living ones produce other chemicals that mask them. Choe\’s team showed that those masking chemicals dissipate within an hour postmortem. I\’m Bob Hirshon for AAAS, the Science Society.