Major population expansion of East Asians began before neolithic time: evidence of mtDNA genomes.

Hong-Xiang Zheng,Yi Wang,Shi Yan,Hui Li,Li Jin,Jing-Ze Tan,Zhen-Dong Qin,Toomas Kivisild

doi:10.1371/journal.pone.0025835

Abstract

It is a major question in archaeology and anthropology whether human populations started to grow primarily after the advent of agriculture, i.e., the Neolithic time, especially in East Asia, which was one of the centers of ancient agricultural civilization. To answer this question requires an accurate estimation of the time of lineage expansion as well as that of population expansion in a population sample without ascertainment bias. In this study, we analyzed all available mtDNA genomes of East Asians ascertained by random sampling, a total of 367 complete mtDNA sequences generated by the 1000 Genome Project, including 249 Chinese (CHB, CHD, and CHS) and 118 Japanese (JPT). We found that major mtDNA lineages underwent expansions, all of which, except for two JPT-specific lineages, including D4, D4b2b, D4a, D4j, D5a2a, A, N9a, F1a1'4, F2, B4, B4a, G2a1 and M7b1'2'4, occurred before 10 kya, i.e., before the Neolithic time (symbolized by Dadiwan Culture at 7.9 kya) in East Asia. Consistent to this observation, the further analysis showed that the population expansion in East Asia started at 13 kya and lasted until 4 kya. The results suggest that the population growth in East Asia constituted a need for the introduction of agriculture and might be one of the driving forces that led to the further development of agriculture.

Highlights

The invention of agriculture was believed to be critical to the expansion of human populations [1,2]
We first estimated the time of lineage expansion using 367 fullgenome mitochondrial DNA (mtDNA) sequences of four available East Asian populations: CHB, CHD, CHS and JPT
After removing the HVS sequences, a median-joining network of mtDNA genomes using Network v4.6 [23] revealed the haplogroup assignments that are consistent with those obtained from Phylotree

Summary

Introduction

The invention of agriculture was believed to be critical to the expansion of human populations [1,2]. The onset of the Neolithic transition in China remains controversial among the archaeologists the earliest appearance of domesticated crops was found in Dadiwan culture at 7.9 kya (thousands of years ago) when broomcorn millet and foxtail millet were cultivated [3,4]. Stronger presence of human activities after Neolithic age suggested recent population expansion after the introduction of agriculture, archeological evidence clearly demonstrated presence of human beings in East Asia throughout the upper Paleolithic period since 40–30 kya [5]. During this period, the last glacial maximum (LGM) occurred at ,20 kya [6]. Upper Paleolithic cultures both before and after the LGM were discovered in China, including Zhoukoudian Upper Cave/ Shandingdong (Beijing, 40 kya), Shiyu (Shanxi, 28.9 kya), Xiaonanhai (Henan, 24.1–18.9 kya), Baiyanjiaodong Cave (Guangxi, 14.6–12.1 kya), Maomaodong (Guizhou, 14.6 kya), Xueguan (Shanxi 13.6 kya), etc. [8] In Japan, the incipient Jomon culture started at ,14 kya [9,10]

Methods

Results

Discussion

Conclusion