And that flies in the face of the dominant view of speech evolution. One of the major differences between human and baboon vowel-like sounds was how similar the different baboon vowel sounds were.

The wahoos, yaks and barks of baboons contain evidence of five vowel-like sounds – a sign that the physical capacity for speech may have evolved much earlier than scientists thought.

A schematic comparing the vocal qualities of certain baboon calls (orange ellipses) with selected vowel sounds of American English, where the phonetic symbols / i æ ɑ ɔ u / represent the vowels ...

Baboons make five distinct vowel-like sounds much like humans, according to new research which suggests language began to evolve about 25 million years ago, much earlier than previously thought ...