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.
Social insects like ants and honeybees are fastidious about
their colony’s tidiness. If any individuals die, they’re quickly
removed and thrown away in one of the nest’s refuse tips. This
behaviour is known as necrophoresis (literally “moving the
dead”) and it protects the remaining colony from any parasites
or diseases that may have killed their former colleague.
Scientists have long believed that ants and bees recognise dead
individuals by smelling chemicals like fatty acids that are
given off by their decaying corpses. But there’s a fatal flaw to
that theory – ants dispose of their p