The father tongue and mother tongue hypotheses in Indo-European populations

New paper (behind paywall) Reconciling the father tongue and mother tongue hypotheses in Indo-European populations, by Zhang et al. National Science Review (2018) nwy083.

Interesting excerpts:

Here, we reassessed the correlation between genetic and linguistic characteristics in 34 modern IE populations (Fig. 1a), for which all four types of datasets (lexicon, phonemes, Y-chromosomal composition, and mitochondrial DNA (mtDNA) composition) are available. We assembled compositions of the Y-chromosomal and mtDNA haplogroups or paragroups from the corresponding IE populations, which reflect paternal and maternal lines, respectively (…)

Neighbour-Nets were constructed to delineate the differences between 34 IE population groups clustering at the genetic and linguistic levels (Fig. 2). The reticulations within each net reflect conflicting signals against tree-like structures and support incompatible groupings [21]. These structures are likely produced by potential horizontal transmissions between populations or languages such as admixture, and potential parallel evolution in linguistics as well [22]. The Neighbour-Net for Y-chromosomes with substantial reticulations shows complicated relationships among IE populations (Fig. 2a), indicating a substantial historical population contact and admixture among the males. In contrast, the Neighbour-Net for mtDNA in Fig. 2b clearly illustrates an East-West geographic polarization, indicating two major IE populations in matrilineages: Indo-Iranian and European. (…)

y-dna-mtdna-phoneme-lexicon
Neighbour-Nets of 34 Indo-European populations calculated from the Euclidean distance matrices using (a) Y-chromosomal haplogroups and (b) mtDNA haplogroups; Neighbour-Nets of IE languages calculated from the Hamming distance matrices using (c) lexicon and (d) phonemes. The colours in the legend correspond to the language groups.

The language learning by local women could constitute the reason for unbalanced correlation of mtDNA to lexicon and phonemes. Due to the social prestige of male immigrants, their local spouses have to adopt the language of their husbands and pass it to future generations [6, 10, 15]. This process is second language acquisition and easily develops language fossilization [31]. The language fossilization is a linguistic mechanism that a learner of a second language tends to preserve some linguistic features of the first language, and develops a form of inter-language [31]. Under this circumstance, women can easily replace the lexicon from another [21], but attempt to retain local accents influenced by their native language [32]. In other words, women change to adopt the same word usage as their husbands in daily life but still speak using their own pronunciation. In mixed-language marriages with these male immigrants, women prefer to pass down their inter-languages to offspring [10, 33]. As a result, it yields the correlation between mtDNA and phonemes we observed. Hence, we courageously proposed a hypothetical scenario in Indo-European populations that lexical system of language dominated by their father, while the phonemic system of language determined by their mother.

I am not a fan of this kind of statistical studies for Comparative Grammar, and there are many pitfalls just by looking at this paper superficially: use of modern languages and modern haplogroup distributions, improper classification of phonemes – as is usual in glottochronological studies – , etc… Which render their results ipso facto unacceptable.

But just yesterday I was discussing where the Copenhagen group and their fans were going to end up when Yamna samples turn out not to be the origin of haplogroup R1a-Z645 expansion, and Anthony’s proposal of a patron-client relationship came up. Since the Danish workgroup is always one step behind, such a reactionary view seems like a reasonable assumption for the future.

This mother tongue vs. father tongue theory is another good possibility for what we are going to see, then, when they use e.g. the exogamy of eastern Corded Ware groups with Yamna to explain the adoption of the language. Maybe that’s what Kristiansen’s invented Yamna → Corded Ware arrows mean… Anything to prove that Corded Ware peoples were Indo-European speakers.

Related

Polygyny as a potential reason for Y-DNA bottlenecks among agropastoralists

polygyny-estimates

Open access Greater wealth inequality, less polygyny: rethinking the polygyny threshold model by Ross et al. Journal of the Royal Society Interface (2018).

Interesting excerpts, from the discussion (emphasis mine):

We use cross-cultural data and a new mutual mate choice model to propose a resolution to the polygyny paradox. Following Oh et al. [17], we extend the standard polygyny threshold model to a mutual mate choice model that accounts for both female supply to, and male demand for, polygynous matchings, in the light of the importance of, and inequality in, rival and non-rival forms of wealth. The empirical results presented in figures 5 and 6 demonstrate two phenomena that are jointly sufficient to generate a transition to more frequent monogamy among populations with a co-occurring transition to a more unequal, highly stratified, class-based social structure. In such populations, fewer men can cross the wealth threshold required to obtain a second wife, and those who do may be fabulously wealthy, but—because of diminishing marginal fitness returns to increasing number of marriages—do not acquire wives in full proportion to their capacity to support them with rival wealth. Together, these effects reduce the population-level fraction of wives in polygynous marriages.

Our model demonstrates that a low population-level frequency of polygyny will be an equilibrium outcome among fitness maximizing males and females in a society characterized by a large class of wealth-poor peasants and a small class of exceptionally wealthy elite. Our mutual mate choice model thus provides an empirically plausible resolution to the polygyny paradox and the transition to monogamy which co-occurred with the rise of highly unequal agricultural populations.

polygyny-pastoralists
(a) Mean frequency of married women who are married polygynously by production system (+2 s.e.) using the Standard Cross-Cultural Sample [30]. Rates of polygyny are measured with variable ]872, per cent of wives with co-wives. (b) Rates of monogamy and polygyny by production system are measured with variable ]861, the standard polygamy code. Data on subsistence come from variable ]858, categorized subsistence. In general, agricultural populations show reduced rates of polygyny and increased rates of monogamy relative to other subsistence systems. See electronic supplementary material for more information. (c) Gini of wealth by production system in our sample.

The reasons for this decrease in marginal fitness returns are explained as either a) a potential missing of important rival forms of wealth in the statistical model, or b) one or more of the following reasons:

  • [A] male’s time and attention are rival inputs to his own fitness (…) A single rich man will have to defend his 10 wives from nine unmarried men on average.”As the wealth ratio grows even more skewed, this situation could become increasingly difficult to manage (e.g. requiring the use of eunochs to defend harems [74]).
  • A related possibility is that a growing number of unmarried men could socially censure wealthy polygynous males, imposing costs on them that reduce male demand for and/or female supply to polygynous marriage [23,24]. (…)
  • A third possibility is that sexually transmitted infection (STI) burden [22,75] could diminish returns to polygyny, if polygyny enhances infection rates [76,77]. (…)
  • Finally, impediments to cooperation or even outright conflict among co-wives can be greater as the number of wives increases. Interference competition among co-wives could impose significant fitness costs in settings where effective child rearing benefits from cooperation [79,80].(…)
polygyny-agropastoralists
between the Gini coefficient on completed rival wealth and per cent completed female polygyny.

I have previously argued against some reasons traditionally given to explain the replacement of native male populations after migrations (i.e. polygyny, slavery, targeted male extermination, etc.), because I believe that a gradual successful expansion of patrilineal clans over some generations based on wealth alone is enough to explain the obvious Y-DNA bottlenecks that happened in many different prehistoric and historic cultures (especially among steppe pastoralists, including Indo-Europeans).

I realize that I haven’t really used any study to support my opinion, though, and data from modern and ancient pastoralists from different regions seem to contradict it, so maybe ancient DNA can show that Indo-Europeans had often children with more than one woman at the same time. I don’t remember seeing that kind of information in supplementary materials to date. From memory I can think of maybe two or three examples of agnate siblings published, but I doubt the archaeological age estimation (based on simple observation of skeletal remains) combined with radiocarbon age (usually given with broad CI) could be enough to prove a similar age of conception. Maybe a case of many siblings clearly of the same age and from many different mothers in the same burial could be a strong proof of this…

I recently read that theoretical models are actually trusted by no one except for the researchers who propose them, and experimental data are trusted by everyone except for the researchers who worked with them. I cannot agree more. However, we lack information about this question (as far as I know), so we may have to rely on indirect estimations, like the kind of models presented in the paper (or the one proposed for Post-Neolithic Y-chromosome bottlenecks).

The Late Proto-Indo-European word for bride comes from a root meaning ‘drive, lead’, hence literally ‘deportation’, so the bride was transferred from her father’s family to her husband’s house. Marriage was certainly an asymmetrical contract for its members, and the reconstructible word for ‘dowry’ further supports the weaker position of the wife in it. Also, ancient marriage could differ from a family agreement, because marriage by elopement, bride kidnapping or hostage was probably common (more or less socially regulated) for people belonging the same culture. Apart from this, I don’t know about reconstructed linguistic data pointing to polygyny, and I doubt archaeological data alone – without genetics – can help.

Related

Modern Hungarian mtDNA more similar to ancient Europeans than to Hungarian conquerors

middle-ages-europe

New preprint at BioRxiv, MITOMIX, an Algorithm to Reconstruct Population Admixture Histories Indicates Ancient European Ancestry of Modern Hungarians, by Maroti et al. (2018).

hungarian-shared-mtDNA
The estimated age distribution of the shared mt Hgs between Hungarians (Hun), the best hypothetical admix (mixFreq) and the populations contributing to this admix: Belgian/Dutch (BeN), Danish (Dan), Basque (Bsq), Croatian/Serbian (CrS), Baltic Late Bronze Age culture (BalBA), Bell Beaker culture (BellB), Slovakian (Slo). The numbers in parentheses indicate the contributions to the best hypothetical admix.

Abstract (emphasis mine)

By making use of the increasing number of available mitogenomes we propose a novel population genetic distance metric, named Shared Haplogroup Distance (SHD). Unlike FST, SHD is a true mathematical distance that complies with all metric axioms, which enables our new algorithm (MITOMIX) to detect population-level admixture based on SHD minimum optimization. In order to demonstrate the effectiveness of our methodology we analyzed the relation of 62 modern and 25 ancient Eurasian human populations, and compared our results with the most widely used FST calculation. We also sequenced and performed an in-depth analysis of 272 modern Hungarian mtDNA genomes to shed light on the genetic composition of modern Hungarians. MITOMIX analysis showed that in general admixture occurred between neighboring populations, but in some cases it also indicated admixture with migrating populations. SHD and MITOMIX analysis comply with known genetic data and shows that in case of closely related and/or admixing populations, SHD gives more realistic results and provides better resolution than FST. Our results suggest that the majority of modern Hungarian maternal lineages have Late Neolith/Bronze Age European origins (partially shared also with modern Danish, Belgian/Dutch and Basque populations), and a smaller fraction originates from surrounding (Serbian, Croatian, Slovakian, Romanian) populations. However only a minor genetic contribution (<3%) was identified from the IXth Hungarian Conquerors whom are deemed to have brought Hungarians to the Carpathian Basin. Our analysis shows that SHD and MITOMIX can augment previous methods by providing novel insights into past population processes.

hungarian-hierarchic-cluster
Unrooted hierarchic cluster of modern and archaic populations based on the SHD matrix.

It is interesting to keep receiving data as to how language does not correlate well with Genomics, whether admixture or haplogroups, even though it is already known to happen in regions such as Anatolia, the Baltic, South-Eastern or Northern Europe.

Thorough anthropological models of migration or cultural diffusion are necessary for a proper interpretation of genetic data. There is no shortcut to that.

hungarian-mtdna
Co-occurrence of Hungarian Bronze Age mt Hgs Distribution of mt Hgs found in Hungarian Bronze Age archaic samples in the analyzed populations. The fixation dates are based on Behar et al [6].

Images made available under a CC-BY-NC-ND 4.0 International license.
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