Singing apes on helium teach evolution of human voice

• Scientists use helium gas to improve frequency of primate’s song

• Gibbon’s calls shatter beliefs of how human voice evolved

A singing gibbon employs the same vocal techniques as professional soprano singers, which shows that gibbons use the same process for producing speech as humans.

The discovery shocked scientists as was previously thought that human speech had evolved through changes in the voice box which were specific to humans.

• Listen to a gibbon’s normal call

• Listen to a gibbon on helium

However, according to the researchers the new study shows the singing gibbons always, and with minimal effort, adopt the complex vocal techniques which are only mastered in humans by professional soprano singers.

This discovery suggests the development of vocal abilities in humans was not due to unique evolutionary modifications.

Dr Takeshi Nishimura from Kyoto University who lead the study said: “The complexity of human speech is unique among primates as it requires varied soft sounds made by the rapid movements of vocal tracts.”

“Our speech was thought to have evolved through specific modifications in our vocal anatomy. However, we’ve shown how the gibbons’ distinctive song uses the same vocal mechanics as soprano singers, revealing a fundamental similarity with humans.”

The Japanese researchers studied the singing of a white-handed gibbon, which boasts a loud melody which can be heard over two miles away.

To explore the human-gibbon vocal similarities the team conducted the first acoustic investigation on non-human primates using helium gas.

The gas is well-known for making human voices appear high pitched, and is useful for studying animal vocal mechanisms as it increases sound velocity and resonance frequencies.

The research reveals that humans share the biological fundamentals of vocalisation with other primates, but in speech have simply acquired another of its most sophisticated forms.

Dr Nishimura added: “This is the first evidence that gibbons always sing using soprano techniques, a difficult vocalisation ability for humans which is only mastered by professional opera singers.

“This gives us a new appreciation of the evolution of speech in gibbons while revealing that the physiological foundation in human speech is not so unique.”

The team recorded 20 gibbon calls in normal air atmosphere, before recording 37 calls in a helium-enriched atmosphere. The resulting sounds reveal how gibbons can consciously manipulate their vocal cords and tract to make their distinctive sound.