TY - JOUR
T1 - Partible paternity, the secondary sex ratio, and a possible Trivers-Willard effect
AU - Beckerman, Stephen
AU - Lizarralde, Manuel
AU - Peluso, Daniela
AU - Yvinec, Cédric
AU - Harris, Nathan
AU - Parker, Daniel
AU - Walker, Robert
AU - Hill, Kim
N1 - Publisher Copyright:
© 2017 by The Wenner-Gren Foundation for Anthropological Research. All rights reserved.
PY - 2017
Y1 - 2017
N2 - Partible paternity, the belief that a child can have more than one biological father, is widespread in lowland South America. An analysis of demographic data sets from four lowland tribes (Aché, Barí, Ese Eja, and Surui) reveals a systematic variation in the sex ratios of live births with respect to the number of fathers to whom the births are attributed. Births attributed to only one father show a sex ratio that is unexceptional for South America; births with two fathers are highly male biased, while children with three or more fathers are female biased. This pattern may be a manifestation of a phenomenon predicted by the Trivers-Willard hypothesis, which proposes that, in many circumstances, females in good condition might bias their offspring toward males, whereas those in poor condition would produce a preponderance of females. If, as suggested below, a woman with a husband and a single extramarital lover tends to be better cared for before and during a pregnancy than other women, this difference might result in the improved maternal condition required by the Trivers-Willard hypothesis for excess males, whereas women who accept two or more lovers might be preponderantly those who are already in distress, thus tending to produce female-biased offspring.
AB - Partible paternity, the belief that a child can have more than one biological father, is widespread in lowland South America. An analysis of demographic data sets from four lowland tribes (Aché, Barí, Ese Eja, and Surui) reveals a systematic variation in the sex ratios of live births with respect to the number of fathers to whom the births are attributed. Births attributed to only one father show a sex ratio that is unexceptional for South America; births with two fathers are highly male biased, while children with three or more fathers are female biased. This pattern may be a manifestation of a phenomenon predicted by the Trivers-Willard hypothesis, which proposes that, in many circumstances, females in good condition might bias their offspring toward males, whereas those in poor condition would produce a preponderance of females. If, as suggested below, a woman with a husband and a single extramarital lover tends to be better cared for before and during a pregnancy than other women, this difference might result in the improved maternal condition required by the Trivers-Willard hypothesis for excess males, whereas women who accept two or more lovers might be preponderantly those who are already in distress, thus tending to produce female-biased offspring.
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U2 - 10.1086/692984
DO - 10.1086/692984
M3 - Article
AN - SCOPUS:85026913149
SN - 0011-3204
VL - 58
SP - 540
EP - 543
JO - Current anthropology
JF - Current anthropology
IS - 4
ER -