A wild African bird that will famously lead people to trees filled with honeycomb seems to somehow learn the distinct whistles and calls of the human foragers who live near them.
Scientists have long puzzled over this unusual cooperative relationship between humans and a wild animal. This bird species, the Greater Honeyguide, is not domesticated at all, and no one trains them.
Yet in Tanzania, Hadza foragers can use a special whistle to attract this bird, which will then flutter down and start chattering away to lead them to honey.
In Mozambique, meanwhile, honey hunters with the Yao community will attract these birds with a trilling sound followed by a low grunt, which sounds like brrr-humph.