Revisiting the Evolutionary History of Pigs via De Novo Mutation Rate Estimation in A Three-generation Pedigree

The mutation rate used in the previous analyses of pig evolution and demographics was cursory and hence invited potential bias in inferring evolutionary history.Herein,we estimated the de novo mutation rate of pigs as 3.6×10-9 per base per generation using high-quality whole-genome sequencing data from nine individuals in a three-generation pedigree through stringent filtering and validation.Using this mutation rate,we re-investigated the evolutionary history of pigs.The estimated divergence time of~10 kiloyears ago(KYA)between European wild and domesticated pigs was consistent with the domestication time of European pigs based on archaeological evidence.However,other divergence events inferred here were not as ancient as previously described.Our estimates suggest that Sus speciation occurred~1.36 million years ago(MYA);European wild pigs split from Asian wild pigs only~219 KYA;and south and north Chinese wild pigs split~25 KYA.Meanwhile,our results showed that the most recent divergence event between Chinese wild and domesticated pigs occurred in the Hetao Plain,northern China,approximately 20 KYA,supporting the possibly independent domestication in northern China along the middle Yellow River.We also found that the maximum effective population size of pigs was~6 times larger than estimated before.An archaic migration from other Sus species originating~2 MYA to European pigs was detected during western colonization of pigs,which may affect the accuracy of previous demographic inference.Our de novo mutation rate estimation and its consequences for demographic history inference reasonably provide a new vision regarding the evolutionary history of pigs.

The Half-industrial and Half-agricultural Working Structure in Rural China

The half-industrial and half-agricultural working structure in rural China is a key phenomenon supporting China's industrialization and urbanization. Based on inter-generational division of labor, the current half-industrial and half-agricultural working structure has given birth to the elderly agriculture and mainstay agriculture, the latter of which has gone out of agricultural involution and to some extent changed the management philosophy of traditional agriculture, becoming a key direction of China's agricultural development. Such a structure has also shaped the "new three-generation family" and facilitated the expansion of middle-income rural groups. While supporting long-term farmers in rural China, it also paves the way for China's urbanization. This structure plays a significant role in the economic, political and social development of rural China. Therefore, this structure is a rural economic structure which concerns farmers' income structure and livelihood patterns. Meanwhile, it is also a rural political structure, village structure and family structure. Through development and refinement, the half-industrial and halfagricultural working structure in rural China has far extended the scope of a descriptive concept. As a dominant variable, the structure, along with its derivatives, through permutation and combination, can establish logical relationships and an interpretation chain among a variety of major economic, political and social phenomena in rural China. Therefore, it can expect to be constructed into an analyticity-oriented mid-level concept.

中国家庭结构的空间分异格局及影响因素——以三代直系家庭为例

Household structure is an important aspect of family change during China’s modernization process.Existing literature has demonstrated significant associations between various factors and household structure,but the spatial variation in these relationships has not been examined.Using the 2010 Chinese population census data and geographically weighted regression(GWR)model,this study explored the spatial patterns of three-generation lineal households,a functionally important household type in China,and its influencing factors.There was significant heterogeneity in the distribution of three-generation lineal households.Socioeconomic,demographic,and cultural factors were all significantly related to the proportion of three-generation lineal households,but the relationships are place-specific in terms of direction and magnitude.These results suggest that the distribution of Chinese household structures cannot be explained by a single framework of family modernization theory but is determined by the interplay of various local characteristics.Especially,population migration plays an equally important role in affecting household structure than socioeconomic development in China.This work contributes to the family literature by highlighting the spatial heterogeneity in the impact of varying factors on household structure.Beyond the classic modernization theory,it sets a contextualized framework for understanding how Chinese household change in response to the rapid social transformation.