Wild birds lead people to honey if they make the right sound

Over the centuries, through genetic and cultural adaptation, humans and a wild bird species have learned to work together with a simple sound: "Brrr-hm."

When human honey-hunters make that call, the bird called the honeyguide does its namesake job with incredible accuracy, leading people to hidden bees' nests.

When biologists compared the "brrr-hm" sound to other sounds, the traditional sound sent the honeyguides to hidden bees nest three times more often than the control sounds, according to a study in the journal Science Thursday.

The people of the region, who make a living on the honey, have axes and other tools that can get at those nests and they use smoke to chase the bees away, reducing the stinging problem.

Richard Wrangham, a Harvard University evolutionary biologist who wasn't part of the study, said this is the most advanced bird-mammal relationship in the world.

The honeyguides are ruthless parasites , depositing their eggs in other species' nests and then, when the baby honeyguide hatches, it kills its foster siblings with a beak that has a hook at the end.