As any young kid can tell you, the best way to win over a crush is through a series of pinches, pokes and pony-tail pulls. But as it turns out, children aren't the only masters of this not-so-subtle romance.
Researchers studying bearded capuchins in Brazil recently observed female monkeys engaged in a novel form of flirtation, with rocks. Because they lack physical indicators of their amorous intent found in other primates, interested females have resorted to vying for the attention of their would-be mates by pelting them with stones.
The female capuchins were also seen whining and making odd expressions, one of which was described by researchers as a "duck face", in their bid for affection.
According to Camila Galheigo Coelho, who studied this behavior, the males apparently have little problem with the indelicate courtship, understanding that the desperate attention-seeking means it's time for baby-making business.
"Similar to the other primates where the male might wait until the swelling has reached its peak in size or redness, capuchin males will wait for the female to display full blown proceptive behaviour in order to guarantee copulation at the most fertile stage," Coelho tells the BBC.