The Origin of Articulate Language Revisited: The Potential of a Semi-Aquatic Past of Human Ancestors to Explain the Origin of Human Musicality and Articulate Language

Key words: swimming, diving, moving in 3 dimensions, mimicking, song, dance, prosody, articulate language, semi-aquatic past. Articulate language depends on very different abilities, such as vocal dexterity, vocal mimicking and the acquirement by children of the very different and arbitrary phonology and grammatical structure of any language. A vast array of experiments confirm that children acquire grammar by the use of prosodic clues, basically intonation and pitch, in combination with, e.g., facial expression and gesture. Prosodic clues, provided by speech, are exaggerated in infant-directed speech (motherese). Moreover, strong overlap between musical and linguistic syntactic abilities in the temporal lobes of the brain has been established. A musical origin of language at the evolutionary level (for the species Homo sapiens) and at the ontogenetic level (for each newborn) is parsimonious and no longer refutable. We then should ask why song, i.e., vocal dexterity and vocal learning, was evolved in our species and why it is largely absent from other 'terrestrial' animals, including other primates, but present in disjoint groups such as cetaceans, seals, bats and three orders of birds? I argue that this enigma, together with a long list of other specifically human characteristics, is best understood by assuming that our recent ancestors (from 3 million years ago onwards) adopted a shallow water diving lifestyle. The swimming and diving adaptations of the upper airway (and vocal) tract led to increased vocal dexterity and song, and to increased fine tuning of motoric and mimicking abilities. These are shared by creatures that can freely move in three dimensions (swimming and flying animals) and that can respond instantaneously to the behavioural changes of other animals. Increased bodily mimicking, together with increased vocal dexterity, both a consequence of a semi-aquatic lifestyle, led to integrated song and dance, which predisposed towards producing and mimicking speech and gesture, and to the ability to use prosodic clues to learn the grammar of whichever language.