Vital to dating a fossil is to be able to carefully evaluate the surrounding stratum in which the fossil is found which possibly could be accurately dated. Embedded within the symptoms of the manic phase of bipolar disorder is the equivalent of such a stratum, which is clearly of strictly Homo sapiens origin.
One of the most central and dramatic behavioral manifestations in mania is the extraordinary hyperactivity in the syntactical (grammatical) functioning of spoken language. I must now confess that there have been occasions in the past when I have been temporarily drawn from my role as physician into stunned fascination by the linguistic virtuosity of a patient who is in the throws of a manic illness. All manner of rhetorical flourishes, beautifully constructed phrases one after another, can pour out in a torrent. Often there is a magnetic quality to this verbal performance the content of which, if one concentrates on it, can consist of a brilliantly creative “flight of ideas.” Beyond the grammar, it is the sheer music of it. In the biography of the mathematical genius, John Nash, A Beautiful Mind (1998), the following description takes place in the McLean Psychiatric Hospital in Boston where Nash was hospitalized for Schizophrenia:
Robert Lowell, the poet walked in, manic as hell. He sees this very pregnant woman. He looks at her and starts quoting the begat sequences in the Bible. Then he started spinning quotes with the word anointed. He decided to lecture us on the meaning of anointed in all the ways it was used in the King James Version of the Bible. In the end I decided that every word in the English language was a personal friend of his.
Linguists are chronically irritated by amateurs like myself impinging on their highly specialized field, particularly when it come to evolution. For that reason, I will restrict my forays into language to being very general and stick to what the experts agree upon. This first generalization is that the syntactical aspect of language, about which much has been learned, is extremely complex and cognitively demanding. Therefore, as Ray Jackendoff puts it in his Foundations of Language (2002 –p.427,) syntax “has the feel of a relatively late innovation.” It is my conviction that the verbal gymnastics that regularly accompany mania fix the disorder as having been part of the suite of adaptations that occurred as part of the evolution of our own species, Homo sapiens.
Then there is a link between vocal language and evidence that strictly human evolution involved sexual selection and display (like the peacock’s tail). In his second magnum opus, The Descent of Man, and Selection in Relation to Sex, Charles Darwin invented the concept of sexual selection & display and then associated it with human evolution particularly with respect to vocal language. Drawing heavily on the example in nature of male bird song, Darwin wrote:
The impassioned orator, bard, or musician, when with his various tones and cadences, he excites the strongest emotions in his hearers, little suspects that he uses the same means by which, at an extremely remote period, his half-human ancestors aroused each other’s passions, during their mutual courtship and rivalry.
In his wonderfully readable and erudite book, The Evolution of Language (2010,) linguist, W. Tecumseh Fitch states that,
The core virtue of the musical protolanguage hypothesis is its logical explanation of the design features shared by song and spoken language, namely the use of the vocal/auditory channel to generate complex, hierarchically structured signals that are learned and shared across generations.
Darwin’s penetrating insight is that the function of the aspect of language that mania reveals we Homo sapiens have brought to the 6 million-year hominin table is tantamount to sexual display, or, more generally, “social display,” traditionally known as vanity.