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.
OBJECTIVE
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 δ(15)N was lower in rural communities than in the urban migrant community, while a sex difference in δ(15)N (higher in males than in females) was found in the former but not in the latter community. Age was not associated with either δ(15)N or δ(13)C values. The analysis of scalp hair samples showed that δ(15)N values were lowest in Levani, the least developed area. Furthermore, there were statistically significant sex differences in δ(15)N values in Levani but not in Tari and Goroka. Age was not associated with either δ(15)N or δ(13)C values.


CONCLUSIONS
The sex inequality in animal protein consumption seems to have decreased as the communities in the Papua New Guinea Highlands have experienced economic development.
Department of Human Ecology, Graduate School of Medicine, The University of Tokyo, Hongo, Tokyo, 113-0033, Japan.
Masahiro
M
Umezaki
Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Japan.
Yuichi I
YI
Naito
Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Japan.
Takumi
T
Tsutaya
Faculty of Urban Liberal Arts, Tokyo Metropolitan University, Tokyo, Japan.
Jun
J
Baba
Department of Human Ecology, Graduate School of Medicine, The University of Tokyo, Hongo, Tokyo, 113-0033, Japan.|Faculty of International Resource Sciences, Akita University, Akita, Japan.
Kiyoshi
K
Tadokoro
Faculty of Letters, Chiba University, Chiba, Japan.
Shingo
S
Odani
Department of Human Ecology, Graduate School of Medicine, The University of Tokyo, Hongo, Tokyo, 113-0033, Japan.|Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Ayako
A
Morita
Faculty of Nursing, The Japanese Red Cross Akita College of Nursing, Akita, Japan.
Kazumi
K
Natsuhara
Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea.
Suparat
S
Phuanukoonnon
Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea.
Gwendalyn
G
Vengiau
Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea.
Peter M
PM
Siba
Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Japan.|The University Museum, The University of Tokyo, Japan.
Minoru
M
Yoneda
D000293:Adolescent; D000328:Adult; D002247:Carbon Isotopes / Q000032:analysis*; D002648:Child; D004044:Dietary Proteins; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D006197:Hair / Q000737:chemistry*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009262:Nails / Q000737:chemistry*; D009587:Nitrogen Isotopes / Q000032:analysis*; D010219:Papua New Guinea; D012535:Scalp / Q000502:physiology; D012737:Sex Factors; D055815:Young Adult
D002247:Carbon Isotopes; D004044:Dietary Proteins; D009587:Nitrogen Isotopes
diet; economic development; protein intake; sex inequality; stable isotope analysis