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第38篇 Night1 of the Living Ants When an ant dies, other ants move the dead insect out of the nest. This behavior is interesting to scientists, who wonder how ants know for sureand so soon-that another ant is dead. Dong-Hwan Choe, a scientist at the University of California2 found that Argentine3 ants have a chemical on the outside of their bodies that signals to other ants, Im dead - take me away. But theres a twist to Choes discovery4. These ants are a little bit like zombies. Choe says that the living ants - not just the dead ones - have this death chemical. In other words, while an ant crawls around, perhaps in a picnic or home, its telling other ants that its dead5. What keeps ants from hauling away the living dead? Choe found that Argentine ants have two additional chemicals on their bodies, and these tell nearby ants something like, wait -Im not dead yet. So Choes research turned up6 two sets of chemical signals in ants: one says, Im dead, the other set says, Im not dead yet. Other scientists have tried to figure out how ants know when another ant is dead. If an ant is knocked unconscious, other ants leave it alone until it wakes up. That means ants know that unmoving ants can still be alive. Choe suspects that when an Argentine ant dies, the chemical that says Wait- Im not dead yet quickly goes away. Once that chemical is gone, only the one that says Im dead is left. Its because the dead ant no longer smells like a living ant that it gets carded to the graveyard, not because its body releases new unique chemicals after death, said Choe. When other ants detect the dead chemical without the not dead yet chemical, they haul away the body. This was Choes hypothesis. | 
