Correlation of Y-haplogroups J2 and J1 with Neolithic agro-pastoral economies

Roy King and Peter Underhill had previously published on the Congruent distribution of Neolithic painted pottery and ceramic figurines with Y-chromosome lineages, in which they found that:

Only the Eu9 [Dienekes: J2-M172] haplogroup successfully predicted the distribution of both Neolithic figurines (88% accuracy) and painted pottery (80% accuracy).

From the paper:

Lifestyle differences exist between agriculturalists and pastoralists (Khazanov 1984). Sedentary agriculturalists and semi-nomadic herders often occupy different ecological niches (Cauvin 2000; Zarins 1990). Dry farming without irrigation is confined to regions of
250-400mm of annual precipitation (Bar-Yosef 1998; Buccellati 1992), while pastoral nomadism is an adaptation to regional semi-aridity (Bellwood 2005; Zarins 1990). It has been shown that the spatial variation of rainfall is important in dictating the structure of endemic flora (Kadmon & Danin 1999). Since the focus of our study is the Neolithic transition, we restrict our analysis of Y-chromosomes and rainfall to the approximate Fertile Crescent ‘homeland’ region implicated in the shift to an agro-pastoralist economy.

...

As predicted, both haplogroups J1 and J2a correlated significantly with annual precipitation. The Spearman correlation tests gave the following results for each haplogroup: J1 r= −0.45, p<0.05; J2a r=0.56, p<0.01; and J2b r=0.00, p (not significant) ... As shown, haplogroup J1
frequency increases as precipitation level reduces below the 400mm per year threshold, typical of semi-arid climates. In contrast, haplogroup J2a frequency reaches a maximum at 700mm per year within the Mediterranean woodland and open parkland zone (Bar-Yosef 1998).

I wonder how these results would change if populations from the Caucasus were included where there are some very significant J1 concentrations that seem to exceed even those of Semitic speaking groups except the Arabians. It's not clear how related the J1 found in places like Daghestan is to that of the Arabian peninsula, or if it resembles the J1 with the short DYS388 alleles found in northeastern Anatolia (where there is high precipitation). Perhaps just as J2a (but not J2b) correlates with high precipitation, a yet-to-be-discovered subclade of J1 is a stronger signal linked to arid climates.

I have been thinking about J1/J2 distribution in West Asia recently; the early surveys of its variation suggested a north/south Fertile crescent dichotomy between the two, but now its distribution looks more like a cross (+) or a T, with a longitudinally constrained J1-rich zone from Arabia to the eastern Caucasus, crossed by a east-west J2-rich zone across the length of the Anatolian peninsula (and indeed into southern Europe) on the west side, and Iran, Pakistan, and India on the east side. What is strange is that both westward and eastward from the central region (the middle point of the +, places like Iraq, eastern Turkey, Syria, northern Iran) the J2/J ratio decreases, approaching ~0.9 in the Balkans, and really 1.0 on the opposite side among the J1-less Hindus.



Antiquity Volume: 82 Number: 316 Page: 281–289

Correlation of annual precipitation with human Y-chromosome diversity and the emergence of Neolithic agricultural and pastoral economies in the Fertile Crescent

Jacques Chiaroni1, Roy J. King and Peter A. Underhill

Examining the beginnings of agriculture in the ‘Fertile Crescent’, this research team has compared the distribution of rainfall with the distribution of Y-chromosome haplogroups. The extended families signalled by J1 and J2 haplogroups seem to have had different destinies in the era of agro-pastoralist experiment: J2 were the agricultural innovators who followed the rainfall, while J1 remained largely with their flocks. Acknowledging the fuzzy edges of such mapping, the authors nevertheless escort us into new realms of the possible for the early history of peoples.

Link