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A picture of an orangutan

The shift from dense forests to open plains in Africa may have caused our ancient ancestors to change their vocal calls, research involving our anthropologists has found.

Researchers studied audible orangutan calls in a South African savannah to measure the different vowel and consonant-based sounds made by the animals and the distance at which they were still audible.

Orangutan calls

As part of the long-term Primate & Predator Project, based at the Anthropology field station in the Soutpansberg Mountains where they played 487 calls from Sumatran and Bornean orangutans and recorded how possible it was to hear them at intervals of 25 metres, up to a distance of 400 metres.

Around 80 per cent of consonant-based calls were audible at 400 metres, while less than 20 per cent of vowel-based calls remained audible at the same distance.

This showed that consonant-based calls remained audible over longer distances compared to vowel-based calls.

Effective consonant-based calls

These findings suggest that consonant-based calls are more effective in open landscapes and were possibly influenced around 5.3 to 16 million years ago, during the middle and late Miocene Era, when Africa's landscapes turned from forests to wide-open grasslands, pushing ancient primates out of the trees and onto the ground.

Since soft tissues don't last in fossils, we can't know for sure how this landscape change affected their voices.

Shaping early human vocal communication

However, great apes make both vowel-like and consonant-like sounds. Orangutans in particular make these in combination, similar to a syllable, and as orangutans spend most of their time in the trees, they are an ideal model to test what changes might have happened when our ancestors  were forced to adapt to their lower ground surroundings.

And as consonants play a significant role in modern human languages, the findings suggest that the transition to open plains might have been pivotal in shaping early human vocal communication.

Find out more

  • Read the full research paper in the journal Scientific Reports.

  • Durham’s role in the research was carried out by Professor Russell Hill in our Department of Anthropology. The research was led by Charlotte Gannon and Dr Adriano Lameira from the University of Warwick.

  • Find out more about the Primate and Predator Project.

  • Our Anthropology Department is one of the largest in the UK and is ranked 23rd in the QS World University Rankings by Subject 2023. Fieldwork is core to our taught programmes, and we offer research-led teaching and hands-on experience to equip our students with the knowledge and skills they need for a successful future. Feeling inspired? Visit our Anthropology webpages for more information on our undergraduate and postgraduate programmes. Durham University is a top 100 world university. In the QS World University Rankings 2024, we were ranked 78th globally.