23 April 2013

Too Many to Communicate

Question 1: Was there a time when all humans spoke the same language?
From what we know (or can infer) about  the social life of early humans in the Middle Paleolithic period (300-30 thousand years ago), our hunter-gatherer ancestors lived in small nomadic bands, each consisting of a few dozen (20-50) individuals. Several such bands may have maintained regular contacts and converged into loose ethnic units (“tribes”) totalling a few hundred members, which gathered seasonally for collective purposes such as ritual celebrations, marital exchange, etc. In such conditions a single speech community, capable of maintaining a shared linguistic code (unified by cultural transmission), can hardly grow larger than a tribe. In effect, a cluster of allied bands corresponds to a linguistic unit as well as a cultural one (with a shared system of customs and laws). Such a model is supported by studies of modern societies retaining an archaic type of organisation, such as the Indigenous Australians. At the time of first European contact, the population od Australia was probably about 300-500 thousand (its exact size is a matter of debate, but most estimates range within those limits). It supported about 250 tribal groups, each with its own language (sometimes more than one). Many of those languages were further subdivided into fairly diverse dialects. While some languages could boast one or two thousand speakers, others had just a few hundred (alas, those that have survived till now too often have only a few). It seems reasonable to assume that the speech communities of Paleolithic hunter-gatherers did not normally exceed about 1000 members.
In order for a single language to spread over the whole human population, that population would have had to be sufficiently small and geographically restricted. Population genetics can estimate past population sizes by reconstructing the family trees of a sample of DNA sequences found in the modern population. Roughly speaking, a population bottleneck at some time in the past narrows down genetic variation and reduces the number of ancestral lineages, as if forcing the genealogies of the modern variants of numerous DNA segments to coalesce within the same period. One recent study (Li &Durbin 2011) uses coalescent simulation applied to the complete human genome to show that the so-called effective population size (N) of non-African humans seems to have dropped down to about 1200 at some time 10-60 thousand years ago. The African effective population was also reduced, though less severely, to about 5,700. Does it mean that the global population of humans was less than 10,000?
Humans were here. Many humans.
Source: Wikimedia Commons
Not quite. The term “effective population” refers to an ideal theoretical model and for a variety of reasons may seriously underestimate the actual number of humans living at the time in question (the “census population”), even by an order of magnitude or so. It is not supposed to be a demographic parameter (which lay people, and even science reporters, may not realise). The Middle Paleolithic census population of Homo sapiens was certainly much larger – in all likelihood, many times larger – than the estimated N values during what is supposed to have been the most serious demographic bottleneck in the history of our species. Whether the total number of humans was closer to 30,000 or to 300,000 is open to debate, but in any case they were far too many of them to constitute one speech community, especially if the Out-of-Africa migrants were already a separate sub-population somewhere in the Near East, the Arabian Peninsula, and possibly elsewhere in Eurasia and/or Australia  (depending on the exact date of the bottleneck). It’s hard to imagine that the same language was spoken in Paleolithic Sub-Saharan Africa and South Asia, no matter how strongly the latter was affected by a demographic crash. No single language, then; at any rate not in anatomically modern humans. We have always been multilingual.



  1. In addition to the points made in the linked article, there is the fact that specific languages are acquired rather than inherited traits. Even if the ancestors of the current human population numbered only a few tens of thousands, that says nothing about how many other people without modern descendants were living at the same time -- and some of those may have spoken languages that have living descendants even though the speakers themselves do not.

  2. As regards people without modern descendants, John Hawks takes that into account (and he mentions non-genetic evidence suggesting a rather large census population). There is a relationship between the effective population and the census population, but it depends on factors such as the structure of social networks, probability of inbreeding, generation overlap, population dynamics, and non-randomness of reproduction -- anything that disturbs the Wright-Fisher model. So far I have not discussed the historical coalescence of linguistic lineages, only the size and structure of Paleolithic populations to see if they might, even in theory, have supported a uniform language.

  3. A fascinating question is to conceptualize what was the "Pre-Language" stage of human evolution, before the use of phonetic communication, using words and sentences. Did it become with clicks, growls, whistling sounds? Perhaps we will never know...

  4. We still use clicks, growls and whistling sounds in paralinguistic non-verbal communication, don't we? (Not to mention gestures, facial expressions etc.)

  5. What features would you say mark human language separately from other forms of communication?

    I think the answers lie in the grammaticality; that is, the application of analytical structure or restructuring yielding a difference of meaning, in novel, spontaneous, sporadic and dynamic ways. Concrete nouns come from calls, verbs from gestures, with grammar to establish a general logical relationship... then what?

    Perhaps the distinguishing mark instead is analogy - but isn't that the heart of grammar? X does Y to Z; A does B to C. To be able to say both, one necessarily makes the implicit analogies X:A , Y:B , Z:C . Perhaps my definitions are off, but this is a fundamental part of what I've called grammaticality. But there comes another problem; my "grammaticality" seems to be emergent, from smaller parts.

    So then, what can one expect out of proto-language? Perhaps a dearth of analogies, say, utter lack of conflation of space and time (and thus possibly an utter lack of tense and aspect?), or lack of modality? Perhaps a lack of abstract nouns or metalinguistics?

    But looking at that, we have human languages claimed to lack some of those features. Some languages can be said to lack aspect; others, tense, at least. I'm sure someone has said one lacks both, if the meaning comes across via pragmatics. Phonemes aren't intrinsic. Word order isn't, morphosyntactic alignment isn't, barely anything is. To say "this is language" and "this is protolanguage" seems as arbitrary as to say "this is orange" and "this is red". Because of this, in addition to the answer above, #1 seems fundamentally flawed, essentially unanswerable, based on flawed if common assumptions.

    That isn't to say there isn't a relative "non-language", "pseudo-language", and "true language", indeed. I'm not claiming birds can talk or humans can't. It just seems to assume that there ever was one discrete homologous thing called Language, when that's plainly not the case. 1's a flawed question, requiring an answer of "無".

    One thing caught my eye regarding argument strength though - most paleoanthropologist as far as I know believe that Homo Ergaster/Erectus lacked language capabilities comparable to modern humans. Yet, he too traveled out of Africa to yield the ancestors of Homo heidelbergensis, neanderthalensis, florensis, and pekingensis. So I don't think traveling out of the biological equivalent of an Urheimat is necessarily conclusive as to whether or not humans had language at a given time, difficult as it may have been. It could be the Ergaster possessed language or offshoot thereof, of course, but to give a yea/nay based on this seems inappropriate, unrelated. Again, another arbitrary line would be drawn, a line similar to saying "this is ergaster" and "this is erectus" or "this is orange" and "this is red". Again, not that arbitrary lines don't have uses, but we're talking about emergent clusters of smaller things, not discrete entities.

    1. Also lions, horses, and many of other terrestrial animals migrated between North America and Eurasia, and Eurasia and Africa. Maybe reaching New Guinea and Australia across open ocean was a special feat requiring technological skills and advanced communication.

      The ability to handle complex syntax (employing recursion and a hierarchy of constituents) and a large lexicon containing thousands of arbitrary signs encoded as combinations of a small number of discrete abstract units -- I think these things are mostly what sets our system of comunication apart. It's especially recursion that seems (to some, at any rate) to have no precursor in animals. One might be tempted to regard it as "irreducibly complex" in the sense that it can't have evolved gradually without a miraculous abrupt rewiring of the human brain. I think such a view is wrong, but I intend to discuss it later.

  6. Maybe it was, but other animals have made it across to Australia and New Guinea especially during periods of glacial highs and oceanic lows, where modern humans still to this day occasionally find that we haven't set foot on all lands. Rafts aren't particular to humans (many are formed just from naturally occurring floatsam, of course), although purposefully made rafts may be, sans certain formic defense mechanisms. Not that the Australian natives didn't posses language, but for ergaster's case personally I want more evidence to make a conclusion, informed or not. We're still in the subjunctive, though, so rationally speaking, of course - that's where we are.

    Regarding irreducible complexity, I do too if my argument looked otherwise. That was partially my point; language is such an encompassing term that for a truly universal un-hazy definition it necessitates reducing the standard.

    Thanks a lot for the reply.

    Sunda and Sahul (as opposed to New Guinea, Australia and Tasmania) were separated by a wide strip of deep ocean throughout the Pleistocene glaciations. Some rodents crossed over to Sahul on natural rafts, presumably already in the Pliocene, bats of course flew in more than 50 million years earlier, but no non-flying mammal larger that a rat ever made it either way except for man.

  8. I know I'm a little late to the party here, but what about the evolution of the language apparatus in the human brain? It's my understanding that a particular evolution in brain structure led to the capacity for "modern language". With that said, wouldn't the structure have evolved in one specific geographic location, resulting in one specific language being spoken in that location, and then migrating outwards with the migration of language-capable humans?

    My understanding of genetics and what paved the way for language is a little shaky, but it seems like by necessity humans, or pre humans, would have at one point all spoken the same language.

    1. I think it's extremely naive to imagine that "the language faculty" evolved saltationally as a result of a rare lucky mutation that suddenly enabled our ancestors to speak. Biological evolution simply doesn't work like that. For one thing, even an advantageous mutation will usually be eliminated by random drift if it occurs infrequently and the effective population is small. If there were only one lucky mutant potentially capable of speaking, such a latent ability alone would not confer any real advantage in the absence of other speakers to communicate with. An how would such a mutant have acquired a language anyway? Children need a lot of exposure to the linguistic production of their elders in order to learn to speak. They can't create a language on their own. And even if they could, talking to oneself is hardly a great adaptive asset.

      For such reasons I am convinced that language must have developed gradually from earlier forms of communication, with many small genetic innovations "paving the way" for it by independently spreading in the population (and synergistically reinforcing one another's effects if they met in the same individual). Not a one-time miracle happening overnight, but rather a number of "evolutionary experiments" running in parallel all across the proto-human population.

    2. That makes sense, thanks for the information.

      I've heard arguments in the past about language functionality evolving its way into the brain as a way of encoding abstract thought rather than a real communication method right of the bat. I'm not sure how evolutionarily beneficial a means of encoding abstract thought is though.

      I think your explanation of language being the product of many smaller adaptations makes a lot more sense.