Japan considered from the hypothesis of farmer/language spread

Abstract

Formally, the Farming/Language Dispersal hypothesis as applied to Japan relates to the introduction of agriculture and spread of the Japanese language (between ca. 500 BC-AD 800). We review current data from genetics, archaeology, and linguistics in relation to this hypothesis. However, evidence bases for these disciplines are drawn from different periods. Genetic data have primarily been sampled from present-day Japanese and prehistoric Jōmon peoples (14,000-300 BC), preceding the introduction of rice agriculture. The best archaeological evidence for agriculture comes from western Japan during the Yayoi period (ca. 900 BC-AD 250), but little is known about northeastern Japan, which is a focal point here. And despite considerable hypothesizing about prehistoric language, the spread of historic languages/ dialects through the islands is more accessible but difficult to relate to prehistory. Though the lack of Yayoi skeletal material available for DNA analysis greatly inhibits direct study of how the pre-agricultural Jōmon peoples interacted with rice agriculturalists, our review of Jōmon genetics sets the stage for further research into their relationships. Modern linguistic research plays an unexpected role in bringing Izumo (Shimane Prefecture) and the Japan Sea coast into consideration in the populating of northeastern Honshu by agriculturalists beyond the Kantō region.

Keywords: Japanese language; Jōmon genetics; Mumun–Yayoi migrations; Yayoi agriculture; language/farming hypothesis.

Graphical abstract

Figure 1.

Map of Japan: prefectures, districts, and placenames mentioned in the text, with Japanese archaeological periodizations. Sources: Periodization from Barnes (2015), tables 1.6, 1.8. Map by TheOtherJesse [public domain], via Wikimedia Commons, modified by GLB [https://commons.wikimedia.org/wiki/File:Regions_and_Prefectures_of_Japan.svg]

Figure 2.

F4-tests surveying the relationship of populations with East Asian ancestry (on the x-axis, ‘X’) to the Ikawazu Jōmon, relative to ancient Southeast Asian foragers (Hòabìnhian, HB), an ancient Tibetan (Chokhopani, CH), and an inland ancient northern East Asian (Shamanka_EN, SH) (graphs by Melinda Yang). Numerical values for the data visualized here can be found in Table S3. F4-statistics are tests of symmetry of the form f4(Out, P1; P2, P3), where it is assumed that P2 and P3 form a clade with espect to P1. Our statistics take the form (A) f4(Mbuti, HB; Ikawazu Jōmon, ‘X’ East Asians) or (B, C) f4(Mbuti, Ikawazu Jōmon; CH or SH, ‘X’ East Asians), with the underlying tree structure verified by other genetic analyses. Central African Mbuti were used as the outgroup (Out).

Figure 3.

Regional interfaces of expanding agriculture and Jōmon lifeways through phases I–V of the Yayoi period, set against the Mumun and Iron Age periods of the Korean Peninsula and the Shellmound periods of the Ryūkyū Islands. Source: Fujio (2013), fig. 3, modified by GLB with permission. Key: 1, instances of bronze introduction and then rejection; 2, abandonment of bronze ritual use; 3, use of bronze bells; 4, moated burials but not moated villages.

Figure 4.

Map of the Japanese tone systems. Adapted by EdB from Wurm and Hattori (1981): no page number.

Figure 5.

Map of vowel centralization of /i/ and /u/ and merger of /i/ and /u/ after coronal consonants. Adapted by EdB from Kamei, Kōno, and Chino (1989), p. 1760.