Association between sex inequality in animal protein intake and economic development in the Papua New Guinea highlands: The carbon and nitrogen isotopic composition of scalp hair and fingernail

Objectives People in the Papua New Guinea Highlands consume sweet potatoes as their dietary staple; consumption of animal protein is limited. In such societies with marginal protein intake, the intra-household allocation of animal protein in terms of sex or age is of importance. The objective of this study was to investigate how the allocation pattern of protein-rich foods by sex and age is associated with economic development in the Papua New Guinea Highlands. Methods The carbon and nitrogen isotopic compositions of fingernails, collected in 1995 in two areas (Tari and Port Moresby [the national capital where Tari migrants resided]), and of scalp hair, collected in 2007, 2012, and 2013 in three areas of different degree of economic development (Levani, Tari, and Goroka) were analyzed. Results Analysis of fingernail samples showed that δ¹⁵N was lower in rural communities than in the urban migrant community, while a sex difference in δ¹⁵N (higher in males than in females) was found in the former but not in the latter community. Age was not associated with either δ¹⁵N or δ¹³C values. The analysis of scalp hair samples showed that δ¹⁵N values were lowest in Levani, the least developed area. Furthermore, there were statistically significant sex differences in δ¹⁵N values in Levani but not in Tari and Goroka. Age was not associated with either δ¹⁵N or δ¹³C values. Discussion The sex inequality in animal protein consumption seems to have decreased as the communities in the Papua New Guinea Highlands have experienced economic development.