Does obstetric protection apply to small‐bodied females?: A comparison between small‐bodied Jomon foragers and large‐bodied Yayoi agriculturalists in the prehistoric Japanese archipelago

Abstract

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.

Obstetric dimensions of the female pelvis are less integrated than locomotor dimensions and show protective scaling patterns: Implications for the obstetrical dilemma

“…At an individual level, most obstetric evidence suggests that shorter women experience a higher frequency of cephalopelvic disproportion (Liselele, Boulvain, Tshibangu, & Meuris, 2000; Mahmood, Campbell, & Wilson, 1988; Tsu, 1992) and caesarean section (Mahmood et al, 1988; Sheiner, Levy, Katz, & Mazor, 2005; Toh‐Adam, Srisupundit, & Tongsong, 2012; Wells, 2017), even if secular trends of increasing height are associated with greater frequency of caesarean section worldwide (Zaffarini & Mitteroecker, 2019). Since height factors into obstetric ease, allometric patterns, too, should account for height, especially among populations with small‐statured mothers (Takamuku, 2019).…”

“…Studies that have examined pelvic variation with height in humans and nonhuman primates have presented diverse results in the pelvis. Some studies suggest that pelvic dimensions do not correlate with height (Kurki, 2011a, 2013; Takamuku, 2019; Wood & Chamberlain, 1986), while others found correlations in certain dimensions (Jagesur, Wiid, Pretorius, Bosman, & Oettlé, 2017; Lewton, 2015; Mobb & Wood, 1977; Sharma, Gupta, & Shandilya, 2016; Tague, 2000). Certain pubic measurements did show correlation (Jagesur et al, 2017) and allometric scaling with height (Mobb & Wood, 1977).…”

Cranial morphometric analysis of early wet-rice farmers in the Yangtze River Delta of China

“…As the local expression of the 'two-layer model' in the Japanese archipelago, it has been proposed that the modern Japanese were formed through a process of mixture between 'native' residents, who had arrived in the Late Paleolithic or Jomon period (c. 14000-800 BCE), and immigrants from the continent from the Yayoi period (c. 800 BCE-300 CE) and later (e.g. Yamaguchi, 1982;Hanihara, 1991;Nakahashi, 1993;Matsumura, 1994;Kaifu, 1997;Kawakubo, 2007;Okazaki and Nakahashi, 2011;Takamuku, 2019;cf. Hudson et al, 2020).…”

Phenotypes and pathways: Working toward an integrated skeletal biology in biological anthropology

“…The number of category 2 articles increase modestly, and these articles further explore the relationships underlying the utility of bone markers used to measure phenotypes of interest. Most articles focus on the structural role of the skeleton (Davies & Stock, 2014; DelPrete, 2019; Frelat & Mittereocker, 2011; Frost, 1998; Rühli, Müntener, & Henneberg, 2005; Takamuku, 2019) and the role of the skeletal system in assisting movement (Niinimäki et al, 2017; Rietsch, Eccard, & Scheffler, 2013).…”