The signals of life - ants use chemical messages to avoid getting trashed

We recognise dead people by the absence of signals that indicate life - movement, responsiveness, pulses, brain activity, and so on. The Argentine ant does the same, but its signal is a chemical one. Throughout its life, an ant uses chemicals in its skin to automatically send out a message to its nest-mates, saying "I'm alive. Don't throw me out." When it dies, these "chemicals of life" fade away, and their bodies are evicted.