The ape and the first word: Understanding the origins and evolution of the first linguistic structures in the human clade through comparative research

Language defines being human, but its evolution defies scientific explanation. Progress has been hampered by what great apes (our closest relatives) presumably can and (mostly) cannot do vocally (i.e. how humans predominantly encode language). This idea derives from historical projects in the 1960s that failed to teach apes to talk.

Critically, however, there was no knowledge then about great apes' natural vocal repertoire, their vocal predispositions, preferences or limitations. My work has recently uncovered that great apes exert control over vocal production to a level far beyond what has been hitherto appreciated, and that they produce, in fact, voiced vowel- and voiceless consonant-like calls, which orangutans further meld into syllable-like combinations.

The project will use these combinations as living models for the first proto-linguistic structures to have emerged within the human clade. Doing so, we will be able, for the first time, to reconstruct the conditions gathered in language's "warm little pond" of proto-vowels and -consonants (to paraphrase Darwin) and uncover the forces that catalysed language onset. I will tackle 5 major theory-, technique- and technology-driven objectives.

(1) Did the rise of consonants trigger language evolution? We will compare orangutan consonant-vowel-like combinations with primate vowel-vowel-like combinations to identify exactly what changed in terms of signal dynamics and evolvability once consonant-like calls became available within our lineage as building blocks for generating composed signals.

(2) How did learning affect the first proto-linguistic structures? Using an original paradigm across wild orangutan populations, we will investigate how learning impacted the (2.1) use and displaced reference, (2.2) acoustics and semantic content and (2.3) organization and syntactic content of the first proto-words of human ancestors.

(3) What level of vocal control did proto-syllable production require? We will quantify, via state-of-the-art remote video-based heart rate sensing technology, the level of arousal vs. control that is in fact involved in vowel- and consonant-like production in apes.

(4) How can the study of great ape vocal behaviour be enhanced, accelerated and preserved for future generations? We will build the first global database of great ape vocal data with free open-access worldwide.

(5) What structural rules evolved in the great ape brain to produce and transmit information and meaning by stringing signals together? We will explore which major computer algorithms can generate signal strings most similar to those produced by great apes in the wild.

Together, these objectives will fling open the door to a new generation of new key insights into the age-old question of language evolution and help understand why, in 3.5 billion years of life of Earth, language only evolved in our direct ancestral lineage.