Objectives
This study examined the relationship between maternal pelvic and body size in the transition from the Middle‐Final Jomon period (c. 5000–3000 BC) to the Middle Yayoi period (c. 400~200 BC to around AD 1) in Japan.
Methods
Eight measurements, including the left hip bone, articulated pelvis, and femur, were taken from Jomon (females: 37, males: 26) and Yayoi skeletal remains (females: 32, males: 29).
Results
A statistically significant decrease in the anterior diameter of the true pelvic inlet was demonstrated in females from the Jomon to the Yayoi period, but not in males. While significant increases in stature from the Jomon to the Yayoi period were found in both males and females, no significant changes in body mass were seen. The correlation coefficients between true and false pelvic measurements (maximum pelvic height and maximum pelvic breadth) and body size (stature and body mass) suggested few significant relationships between true and false pelvic measurements or body size among the samples, but no significant correlations in small‐bodied Jomon females. Results of principal component analysis using the log‐size and log‐shape variables suggested that the true pelvic size in Jomon and Yayoi females was not correlated with their general pelvic or body size, and there were correlations between sexually dimorphic aspects of true pelvis shape and either the false pelvis or body size in males but not females.
Conclusions
These results suggest that the obstetrical dimensions in small‐bodied Jomon females were maintained for obstetric needs.
The Yangtze River Delta is the best-known homeland of wet-rice agriculture. From the Middle Neolithic, rice farming expanded from the Yangtze region to both the north and the south. However, poor preservation of ancient human skeletal remains in the region has meant that the population history of these expansions has not been fully understood. In order to clarify the ancestry of early wet-rice farmers in East Asia, we conducted a cranial morphometric analysis and comparison of a Middle Neolithic skeletal assemblage excavated from the Guangfulin site, Shanghai. The results of bivariate and multivariate analyses showed that: (1) Neolithic wet-rice farmers from the lower Yangtze retained local morphological characteristics, but were nevertheless morphologically more similar to Neolithic and later populations in northern China, which was home to early millet farmers, than to Neolithic populations in south China; and (2) Neolithic and later agricultural populations in East Asia were morphologically homogeneous compared to pre-Neolithic hunter-gatherer groups even though the area occupied by both was equally vast. These results suggest, respectively, that: (1) Middle Neolithic wet-rice farmers in the Yangtze Delta experienced significant gene flow from regions of northern China such as the Central Plains and Shandong even though there is currently no evidence that millet cultivation itself had yet reached the delta region; and (2) Neolithic populations resulting from interaction between the Yangtze Delta and northern China dispersed widely across much of East Asia including the Japanese archipelago together with the spread of wet-rice agricultural technologies. These two proposals are paralleled by recent stable isotope analyses using tooth enamel and bone collagen, as well as archaeological evidence from Shandong. Finally, a facial approximation was conducted using a cranium (M252) excavated from Guangfulin for the purpose of visually expressing the results of this study.
This study examined the temporal changes of the bony-birth canal from Jomon to modern Japanese in order to test the hypothesis that the bony birth-canal form of the mother is one of the decision factors of the cranial shape. The outcomes are as follows, Jomon population had the biggest bony-birth canal. In Yayoi and the
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