"Modernization" increases parental investment and sibling resource competition: evidence from a rural development initiative in Ethiopia
"Modernization" increases parental investment and sibling resource competition: evidence from a rural development initiative in Ethiopia
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DOI：
10.1016/j.evolhumbehav.2010.10.002
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发表时间：
2011-03-01
影响因子：
5.1
通讯作者：
Lawson, David W.
中科院分区：
文献类型：
--
作者：
Gibson, Mhairi A.;Lawson, David W.
亲本投资的进化模型通常假设后代之间竞争的负面影响（即，数量-质量权衡效应）在资源稀缺的条件下最为明显。然而，与“现代化”相关的资源获取的改善可能会降低外部环境风险的水平，从而在父母的投资和后代的成功之间建立更强的联系。在这里，我们提供的证据表明，在埃塞俄比亚的农村发展计划与增加水平的父母投资后代的地位和竞争水平的兄弟姐妹之间的这种投资。与邻近没有水龙头的村庄相比，供水得到改善的村庄儿童死亡率降低，教育投资增加，子女受教育的可能性更多地取决于家庭中的地位。然而，没有证据表明父母对直接与儿童健康有关的基层资源的投资增加（以儿童疫苗接种率表示）。教育投资可能对死亡率的变化更敏感，尽管其成本很高，而且对基本功能来说是“多余的”，因为它有可能为儿童带来最大的经济回报，例如，从新兴的工资劳动力市场的工作岗位上。虽然自来水村目前与较高的出生率有关，但我们预计，随着时间的推移，随着计划生育的改善，生育率将下降，以应对环境风险的变化和提高父母高投资战略的回报。这些村庄可能正处于人口结构向小家庭过渡的初期阶段。(C)2011 Elsevier Inc. All rights reserved.
Evolutionary models of parental investment often assume that negative effects of competition between offspring (i.e., quantity-quality trade-off effects) will be most apparent under conditions of resource scarcity. However, improvements in resource access associated with "modernization" may reduce levels of extrinsic environmental risk, creating a stronger association between parental investment and offspring success. Here we provide evidence that a rural development initiative in Ethiopia is associated with increased levels of parental investment in offspring status and increased levels of competition for this investment between siblings. Villages with access to an improved water supply, which have reduced levels of childhood mortality, are associated with higher investments in education, and the likelihood of offspring education is more determined by position within the family, compared to neighboring villages without access to water taps. However, there is no evidence of higher parental investment of base-level resources directly related to child health (indicated by childhood vaccination rates). Educational investment may be more sensitive to mortality changes, despite being costly and "surplus" to essential functions, because it has the potential to introduce the greatest economic payoffs for children, e.g., from jobs in an emerging wage-labour market. While tap villages are currently associated with a higher birth rate, we anticipate that in time, and with improved access to family planning, fertility will drop in response to shifts in environmental risk and improved pay-offs to strategies of high parental investment. These villages may be experiencing the initial stages of a demographic transition to small family sizes. (C) 2011 Elsevier Inc. All rights reserved.