Blute Blog

Blute's blog about evolutionary theory: biological, sociocultural and gene-culture.

Archive for March 2010

Was there a "mother tongue"?

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I was rather cautious in Darwinian Sociocultural Evolution about the possible existence of a “mother tongue” of all human languages (sometimes called “proto-world” or “proto-sapiens”). I would be less inclined to be so today on the basis of the genomic evidence for our “recent out-of-Africa” origin.

About 50,000 years ago one or at most two small groups of anatomically and behaviourally modern humans Homo sapiens sapiens (perhaps only 150 or so individuals and probably speaking a language with many phonemes, many of them “click” sounds of various kinds) migrated out of Africa, stimulated possibly by climate change. By 10,000 years ago or so  i.e. in only 40,000 years, through subsequent repeated migrations, their descendants had spread out to displace earlier migrants, to inhabit the furthest reaches of all continents except Antarctica, and to eventually give rise to the named cultures and languages of the anthropological literature.  That is the story that has emerged from the human genomic evidence gathered and analyzed initially by Luigi Cavalli-Sforza of Stanford University and subsequently by Spencer Wells and associates in The Genographic Project among others (for accessible treatments see Wade 2007, Wells 2007).

Because specific languages (albeit not the capacity for language) is acquired socioculturally, the implication of these findings is that all human languages on earth today have descended with modification socioculturally from one or two common ancestral languages. Since no one thinks it possible that language evolved later than 50,000 years ago and some think much earlier, that is the inescapable conclusion from the genomic evidence – unless one wished to argue that one or more groups stopped talking for some generations and then began anew again which seems most unlikely.

I will add immediately that this conclusion cannot be drawn directly from the linguistic evidence – language does changes rapidly on this time scale of tens of thousands of years and phylogenetic signals eventually get lost. Historical linguists therefore tend to argue that while this story may be true, we will never know for sure. Others however think it more prudent to say “never say never in science”.  In the meantime, cultural descent with modification including of languages is consistent with what we know on smaller but still large temporal and spatial scales – the some 200 language families within each of which the languages can be shown on linguistic grounds to be historically related by common descent. The large Indo-European family of course was known even in Darwin’s time who used it as an analogy for his biological theory of descent with modification. There are at least some cases in which these language families in turn have been shown to be historically related. And of course there is similar research on other areas of culture such as social organization and material culture (both prehistoric i.e. archaeological and historic).

Written by Marion Blute

March 21, 2010 at 10:56 pm

Sociocultural Phylogenetics

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The text of Darwinian Sociocultural Evolution: Solutions to Dilemmas in Cultural and Social Theory went in at the end of March 2009, so it was almost a year before it was published. I would not change the thesis of the whole nor of each chapter today, but new material continues to come out which I would like to comment on in an informal context, while also posting about more general evolutionary issues.

For example, remarkable empirical results in sociocultural phylogenetics continued to be produced in 2009. Gray Drummond and Greenhill, extending an earlier analysis, applied Bayesian phylogenetic methods [gated] to 210 lexical items of 120 languages to shed light on the peopling of the Pacific. Their analysis concluded that the evolution of Austronesian languages was closely coupled with the geographic expansion of people and proceeded in a series of pulses interrupted by pauses originating in modern day Taiwan around 5,230 years ago and ending eventually in New Zealand between 1200 and 1800 years ago. They hypothesize that the pulses were the result of technological inventions, originally the outrigger canoe.

In related work, Jordan, Grey, Greenhill and Mace matched ethnographic data for 135 of these societies and with the same 210 lexical items and were able to infer that matrilocal rather than patrilocal or ambilocal post-marital residence was the original ancestral state of these societies. Finally, Rogers, Feldman and Ehrlich developed a method for identifying historical sequences in cultural data even in the presence of horizontal exchange and applying it to a set of data on Polynesian canoe design traits, they were able to infer Fiji as the ancestral homeland of these traits, that cultural distance increased with geographic distance, and that there was a serial founder effect of declining diversity with distance culturally just as there normally is genetically.

It is remarkable that these three studies show that applications of methods originating in biology can be used to reconstruct ancestral states and infer details of human cultural history across 5,000 years – linguistic in the first case, social organizational in the second and technological in the third. Knowledge across five thousand years may not seems like much to a paleontologist, a paleoanthropologist or even an archaeologist but to cultural anthropologists and sociologists it is remarkable.

Written by Marion Blute

March 4, 2010 at 2:31 am