Journey to the east: Diverse routes and variable flowering times for wheat and barley en route to prehistoric China.

Today, farmers in many regions of eastern Asia sow their barley grains in the spring and harvest them in the autumn of the same year (spring barley). However, when it was first domesticated in southwest Asia, barley was grown between the autumn and subsequent spring (winter barley), to complete their life cycles before the summer drought. The question of when the eastern barley shifted from the original winter habit to flexible growing schedules is of significance in terms of understanding its spread. This article investigates when barley cultivation dispersed from southwest Asia to regions of eastern Asia and how the eastern spring barley evolved in this context. We report 70 new radiocarbon measurements obtained directly from barley grains recovered from archaeological sites in eastern Eurasia. Our results indicate that the eastern dispersals of wheat and barley were distinct in both space and time. We infer that barley had been cultivated in a range of markedly contrasting environments by the second millennium BC. In this context, we consider the distribution of known haplotypes of a flowering-time gene in barley, Ppd-H1, and infer that the distributions of those haplotypes may reflect the early dispersal of barley. These patterns of dispersal resonate with the second and first millennia BC textual records documenting sowing and harvesting times for barley in central/eastern China

Correction: Journey to the east: Diverse routes and variable flowering times for wheat and barley en route to prehistoric China.

[This corrects the article DOI: 10.1371/journal.pone.0187405.]

Correction: Journey to the east: Diverse routes and variable flowering times for wheat and barley en route to prehistoric China.

[This corrects the article DOI: 10.1371/journal.pone.0187405.]

References to planting and harvesting time of barley/wheat in ancient Chinese texts from the first millennium BC.

<p>See Table A S1 File for original texts/translations and more information about the chronology of the texts.</p

The implied ‘first appearance dates’ (i.e. ‘Start’ <i>Boundaries</i>) of the fifteen regions derived from the Bayesian statistical model (green).

<p>The contributing radiocarbon data are additionally plotted (with modeled data in darker gray overlying the unmodeled, calibrated data in lighter gray). The horizontal bars below each of the probability density functions reflect the 68.2% and 95.4% highest probability density ranges, respectively.</p

Journey to the east: Diverse routes and variable flowering times for wheat and barley <i>en route</i> to prehistoric China

<div><p>Today, farmers in many regions of eastern Asia sow their barley grains in the spring and harvest them in the autumn of the same year (spring barley). However, when it was first domesticated in southwest Asia, barley was grown between the autumn and subsequent spring (winter barley), to complete their life cycles before the summer drought. The question of when the eastern barley shifted from the original winter habit to flexible growing schedules is of significance in terms of understanding its spread. This article investigates when barley cultivation dispersed from southwest Asia to regions of eastern Asia and how the eastern spring barley evolved in this context. We report 70 new radiocarbon measurements obtained directly from barley grains recovered from archaeological sites in eastern Eurasia. Our results indicate that the eastern dispersals of wheat and barley were distinct in both space and time. We infer that barley had been cultivated in a range of markedly contrasting environments by the second millennium BC. In this context, we consider the distribution of known haplotypes of a flowering-time gene in barley, <i>Ppd-H1</i>, and infer that the distributions of those haplotypes may reflect the early dispersal of barley. These patterns of dispersal resonate with the second and first millennia BC textual records documenting sowing and harvesting times for barley in central/eastern China.</p></div

Direct radiocarbon dates for archaeobotanical barley grains from East, Central and South Asia.

<p>Data include radiocarbon determinations carried out in this study and those that have been previously published. The radiocarbon data have been calibrated using the IntCal13 calibration curve, and are presented at the 95.4% probability range.</p

The ‘first appearance dates’ of barley derived by Bayesian statistical modeling for fifteen regional groupings (further grouped into seven broader regional groupings) of archaeological sites across central, south and east Asia.

<p>(See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0187405#sec010" target="_blank">Supporting Information</a> for full details regarding the model construction). The horizontal bars below each of the probability density functions reflect the 68.2% and 95.4% highest probability density ranges, respectively. These results show a north to south chronological sequence of the first appearance dates of barley within South Asia, and a south to north sequence between South and East Asia.</p