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  • how do ants know when another ant is dead?

    when ed wilson was a young assistant professor at harvard in the 1950s, he observed that when ants die — and if they're not crushed and torn apart — they just lie there, sometimes upside down, feet in the air, while their sister ants (almost all ants in a colony are ladies) walk right by without a glance. that is until about two days after an ant's passing, ed discovered, when the corpse appears to emit a chemical signal that changes the living ants' behavior dramatically.

    all of a sudden what was once a pile of gunk on the colony floor becomes a "problem to be solved." once the signal is in the air, any ant that happens by grabs the corpse and carries it through the colony to a refuse pile designated the graveyard and dumps it on a mound of also-dead ants.

    ed, who would revolutionize the study of ants by exploring their ability to communicate with smell, decided to figure out what chemicals equal "i am dead" to an ant.

    in his autobiography, naturalist, he wrote: "i thought, maybe with the right chemicals i could create an artificial corpse."

    finally, after much sifting and mixing, ed discovered that oleic acid — just a teeny drop of it — was all the ants had to sniff to think "dead!" and, because he could — ed had a colony parked in his harvard lab so he could watch them endlessly — one day he took a drop of the chemical and gently deposited it on an ant that had the misfortune of walking by.

    ed describes how as soon as he dabbed the ant, the next ant that came near grabbed his ant, slung it on its back, hiked over to the graveyard and though the ant was very much alive — "kicking, you know," says ed — flung it onto the refuse pile.

    dead is what you smell — not what you see — if you are an ant. so, though it tried to clean itself over and over, the minute it returned to the colony, it was grabbed, carried and slung back on the pile.