Gibbons adapt their vocalizations when singing duets

ALTHOUGH white-handed gibbons, or lar gibbons, are shy by nature, they are nonetheless very vocal. European researchers have been studying the richness of their vocalizations. They discovered that these little monkeys don't sing in quite the same way when performing solo or with a partner.

A team of researchers from the University of Turin recorded and studied the vocalizations of white-handed gibbons living in a nature reserve in Thailand and in a zoo in Italy, with the help of two colleagues from other European universities. In detail, they analyzed 215 recordings of songs emitted by 12 gibbons.

In particular, the scientists recorded the notes, allowing them to discern sound patterns, and measured the intervals and interleaving of notes during duets between the primates.

Indeed, white-handed gibbons often partake in duets in which males and females alternate their vocalizations, like most other primates belonging to the hominoid superfamily.

These collaborations fulfill different functions, such as meeting partners or the cooperative defense of a common territory.

However, Teresa Raimondi and her colleagues found that white-handed gibbons do not sing in the same way depending on their sex or that of their partner. Males tend to put more rhythm into their vocalizations when accompanied by a female. They also sing more than their partner during duets.

The researchers see this as evidence that rhythm plays a social role in white-handed gibbon groups. This hypothesis could explain why females are much more rhythmically flexible than their male counterparts. But in any case, male and female gibbons alternate their vocalizations when singing in pairs.

"The timing of phonation of each individual in a duet is predicted by the timing of the co-singer's vocalizations, suggesting a potential rhythmic interaction," write the researchers in their findings, recently published in the journal, Proceedings of the Royal Society B: Biological Sciences.

Deciphering the songs of white-handed gibbons is crucial to determining the origin of human language, and its specificities.

Researchers at the German Primate Center in Göttingen have discovered that some gibbon species communicate with each other using language specific to the region in which they live.

They share a dialect but use different "accents," as reports one study published in 2011 in the journal BMC Evolutionary Biology. All of which serves to prove that primates share many similarities with their human cousins.