Early sexual maturity among Pumé foragers of Venezuela: Fitness implications of teen motherhood

Abstract

Because humans have slow life histories, discussions of the optimal age at first birth have stressed the benefits of delayed reproduction. However, given the diversity of ecological, fertility, and mortality environments in which humans live, reproductive maturity is expected to be highly variable. This article uses reproductive histories to examine a pattern of early menarche and first birth among the Pume, a group of South American foragers. Age at menarche and first birth are constructed using both retrospective and cross-sectional data for females over the age of 10 (n = 83). The objectives are first to define these patterns and then discuss their reproductive consequences. On average, Pume girls reach menarche at age 12.9, and give birth to their first child at age 15.3-15.5 (retrospective and cross-sectional data, respectively). This populational average falls several years prior to what often is considered the human norm. Two questions are then considered. What are the infant mortality costs across a mother's reproductive career? How does surviving fertility vary with age at first birth? Results indicate that the youngest of first-time mothers (<14) are four times more likely to loose their firstborns than older first-time mothers (> or =17). Given parity-specific mortality rates, the optimal strategy to minimize infant mortality and maximize reproductive span is to initiate childbearing in the midteens. Women gain no additional advantage in surviving fertility by delaying childbearing until their late teens.

Infant growth and the thymus: Data from two South American native societies

“…It is therefore likely that unmeasured variation in maternal condition contributes to differences in thymus size in newborns. Both populations of mothers measured were similar in weight after controlling for pregnancy status, however, Pumé mothers experience profound seasonal fluctuations in nutritional status (Kramer, 2008) that are not observed in Tsimane mothers. In addition to pronounced nutritional fluctuations, Pumé mothers experience greater epidemiologic stress and less access to health care than do Tsimane mothers.…”

“…Fertility is high (cohort fertility rate for women aged >40 5 7.41 for savanna and 7.75 for river women) (Kramer and Greaves, 2007). Most girls marry by 15 years and average age at first birth is 15.5 years (Kramer et al, 2009;Kramer 2008). There is no formal post-partum isolation of mothers and newborns.…”

Anthropological Data Regarding the Adaptiveness of Hebephilia

“…Finally, Kramer's (2008) work on the hunting and gathering savanna Pumé of Venezuela echoes Blanchard's findings on reproductive success and attraction. Kramer compared the number of surviving children born to women who began their reproductive careers early (<14 years), mid (14-16 years), and late (≥17 years).…”

Should I Stay or Should I Go? Hunter-Gatherer Networking Through Bilateral Kin

“…In many groups of hunter-gatherers, parents and other relatives help support young couples, who may not yet be mature food producers (Bogin 1999;Hrdy 2005;Kaplan 1996;Kramer 2008;Kramer and Greaves 2010;Kramer, Greaves and Ellison 2009). Rather than restricting access to kin, bilateral association can make it possible for couples to situationally locate with the kin of either spouse in response to demographic changes in family composition.…”

“…Genealogical data are freely and enthusiastically discussed about both living and dead individuals. Interview methods to determine ages and kin relations are detailed in previous studies (Kramer 2008;Kramer andGreaves 2007, 2010;Kramer, Greaves and Ellison 2009). Indigenous censuses of the Pumé were carried out in 1982, 1986and 1992.…”