The concept of "Proto-Human" presupposes monogenesis (evolution from a common ancestor) of all natural languages apart from pidgins, creoles, and sign languages. It does not presuppose a common ancestor of these languages with all extinct lineages, whether human or possible Neanderthal languages.
There is no generally accepted term for this concept. Most treatments of the subject do not include a name for the language under consideration (e.g. Bengtson and Ruhlen 1994). The terms Proto-World and Proto-Human are in occasional use. Merritt Ruhlen has been using the term Proto-Sapiens.
History of the idea
The first serious scientific attempt to establish the reality of monogenesis was that of Alfredo Trombetti, in his book L'unità d'origine del linguaggio, published in 1905 (cf. Ruhlen 1994:263). Trombetti estimated that the common ancestor of existing languages had been spoken between 100,000 and 200,000 years ago (1922:315).
Monogenesis was dismissed by many linguists in the late 19th and early 20th centuries, when the doctrine of the polygenesis of the human races and their languages was widely popular (e.g. Saussure 1986/1916:190).
The best-known supporter of monogenesis in America in the mid-20th century was Morris Swadesh (cf. Ruhlen 1994:215). He pioneered two important methods for investigating deep relationships between languages, lexicostatistics and glottochronology.
In the second half of the 20th century, Joseph Greenberg produced a series of large-scale classifications of the world's languages. These were and are controversial but widely discussed. Although Greenberg did not produce an explicit argument for monogenesis, all of his classification work was geared toward this end. As he stated (1987:337): "The ultimate goal is a comprehensive classification of what is very likely a single language family."
Date and location
The first concrete attempt to estimate the date of the hypothetical ancestor language was that of Alfredo Trombetti (1922:315), who concluded it was spoken between 100,000 and 200,000 years ago. This estimate happens to agree with estimates on the age of Homo sapiens, with the maximum estimate being 300 kya.
While earliest known fossils of anatomically modern humans date from around 195,000 years ago, the matrilinear most recent common ancestor shared by all living humans (the Mitochondrial Eve), is dated to about 120–150 thousand years ago. The divergence of the three main descendant lines within Africa, L1/A in Southern Africa (Khoisan/Capoid peoples), L2/B in Central and West Africa (Niger–Congo- and Nilo-Saharan-speaking peoples, Mbuti pygmies), and L3 (East Africa, Out-of-Africa migration), dates to about 100 to 80 thousand years ago.
It is uncertain or disputed whether the earliest members of Homo sapiens had fully developed language. Some scholars link the emergence of language proper (out of a proto-linguistic stage that may have lasted considerably longer) to the development of behavioral modernity towards the end of the Middle Paleolithic or at the beginning of the Upper Paleolithic, roughly 50,000 years ago. Thus, in the opinion of Richard Klein, the ability to produce complex speech only developed some 50,000 years ago (with the appearance of modern humans or Cro-Magnons).
The fact that Australian Aborigines diverged from other human lineages 70–75,000 years ago suggests that Proto World was spoken just before the spread of humanity out of Africa.
The difficulty in making any statement on particulars of Proto-Human, even whether it existed, lies in the time depth involved, which scientific consensus holds is far beyond what linguists can reconstruct (between five and ten millennia in the cases of Proto-Indo-European and Proto-Afroasiatic). Of the relatively few linguists who have discussed the subject, most suppose that it would have shared the "design features" of modern human languages, such as grammar (in the sense of "fixed or preferred sequences of linguistic elements"), and recursion ("clauses [or phrases] embedded in other clauses [or phrases]"), but that beyond this nothing can be known of it (Campbell and Poser 2008:391).
A few linguists, such as Merritt Ruhlen, claim that this difficulty can be overcome by means of mass comparison and internal reconstruction (cf. Babaev 2008). A number of linguists have attempted to reconstruct the language, while many others reject this as fringe science.
According to research by Murray Gell-Mann and Merritt Ruhlen, the ancestral language had a basic order of Subject (S) - Object (O) - Verb (V) or SOV. Although not applicable to the Romance languages like French and Spanish, the SOV order is still found in today's languages such as Japanese, Korean, Turkish, Basque, Georgian, and many more. 
Ruhlen tentatively traces a number of words back to the ancestral language, based on the occurrence of similar sound-and-meaning forms in languages across the globe. Bengtson and Ruhlen (1994) identify 27 "global etymologies". The following table, adapted from Ruhlen (1994b), lists a selection of these forms:
- Source: Ruhlen 1994b:103. The symbol V stands for "a vowel whose precise character is unknown" (ib. 105).
Based on these correspondences, Ruhlen (1994b:105) lists these roots for the ancestor language:
- ku = 'who'
- ma = 'what'
- pal = 'two'
- akwa = 'water'
- tik = 'finger'
- kanV = 'arm'
- boko = 'arm'
- buŋku = 'knee'
- sum = 'hair'
- putV = 'vulva'
- čuna = 'nose, smell'
In a 2011 paper, Murray Gell-Mann and Merritt Ruhlen argued that the ancestral language had subject–object–verb (SOV) word order. The reason for thinking so is that in the world's natural language families, it is typical for the original language to have an SOV word order, and languages that evolve from it sometimes deviate. Their proposal develops an earlier one made by Talmy Givón (1979:271–309).[how?]
Languages with SOV word order have a strong tendency to have other word orders in common, such as:
- Adjectives precede the nouns they modify.
- Dependent genitives precede the nouns they modify.
- "Prepositions" are really "postpositions", following the nouns they refer to.
For example, instead of saying The man goes to the wide river, as in English, Ruhlen's Proto-Human speakers would have said Man wide river to goes. However, half of all current languages have SOV order, and historically languages cycle between word orders, so finding evidence of this order in the reconstructions of many families may reflect no more than this general tendency, rather than reflecting a common ancestral form.
Many linguists reject the methods used to determine these forms. Several areas of criticism are raised with the methods Ruhlen and Gell-Mann employ. The essential basis of these criticisms is that the words being compared do not show common ancestry; the reasons for this vary. One is onomatopoeia: for example, the suggested root for 'smell' listed above, *čuna, may simply be a result of many languages employing an onomatopoeic word that sounds like sniffing, snuffling, or smelling. Another is the taboo quality of certain words. Lyle Campbell points out that many established proto-languages do not contain an equivalent word for *putV 'vulva' because of how often such taboo words are replaced in the lexicon, and notes that it "strains credibility to imagine" that a proto-World form of such a word would survive in many languages.
Using the criteria that Bengtson and Ruhlen employ to find cognates to their proposed roots, Lyle Campbell finds seven possible matches to their root for woman *kuna in Spanish, including cónyuge 'wife, spouse', chica 'girl', and cana 'old woman (adjective)'. He then goes on to show how what Bengtson and Ruhlen would identify as reflexes of *kuna cannot possibly be related to a proto-World word for woman. Cónyuge, for example, comes from the Latin root for meaning 'to join', so its origin had nothing to do with the word 'woman'; chica is a feminine adjective coming from a Latin noun meaning 'worthless object'; cana comes from the Latin word for 'white', and again shows a history unrelated to the word 'woman' (Campbell and Poser 2008:370–372). Campbell's assertion is that these types of problems are endemic to the methods used by Ruhlen and others.
There are some linguists who question the very possibility of tracing language elements so far back into the past. Campbell notes that given the time elapsed since the origin of human language, every word from that time would have been replaced or changed beyond recognition in all languages today. Campbell harshly criticizes efforts to reconstruct a Proto-human language, saying "the search for global etymologies is at best a hopeless waste of time, at worst an embarrassment to linguistics as a discipline, unfortunately confusing and misleading to those who might look to linguistics for understanding in this area" (Campbell and Poser 2008:393).
- Adamic language
- Borean languages
- Linguistic universals
- List of languages by first written accounts
- List of proto-languages
- Origin of language
- Origin of speech
- Polygenesis (linguistics)
- Recent African origin of modern humans
- Universal grammar
- Used by the Harold Fleming (2003) and John Bengtson (2007).
- CARTA: The Origin of Us -- Christopher Ehret: Relationships of Ancient African Languages. August 1, 2013.
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- Gell-Mann & Ruhlen (2003:3–4)
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