Doctoral Dissertation Research: Testing theories of mutualism in the context of rapid culture change

世界各地的人类社会都在应对危及生计的不利社会和环境条件，但他们也倾向于发展有助于适应这些条件的传统和制度。例如，在美国西南部，干旱和洪水会威胁到牧场主。作为回应，农场主们发展了一种叫做“邻居”的社会制度，农场主们帮助有需要的邻居。然而，当经济迅速变化时，像邻国这样的机构会发生什么？在世界各地，放牧可能是一种高风险的生计，由于干旱、疾病和某些国家的袭击，畜群规模通常容易突然波动。牧民们通常都有类似的牲畜友谊，或者是牛的借贷和分享网络。一些研究人员认为，家畜友谊可能是一种非正式保险系统的例子，可以防止牲畜损失，而另一些人则声称，随着时间的推移，它们可能有助于积累牲畜财富和家庭之间的政治影响力。亚伦·莱特纳在华盛顿州立大学爱德华·哈根博士的指导下，对坦桑尼亚的马赛族牧民进行了调查，他们几个世纪以来一直以放牛为生。然而，最近，人口增长、干旱和城市化迫使许多马赛牧民转向农业和现金经济，减少对高风险的放牛业务的依赖，这对当地经济来说是一个突然的、根本性的变化。本研究将调查牲畜友好机构如何适应不断变化的经济，收集来自牛、农业和其他来源的家庭收入数据；伴侣偏好和声誉；股票朋友之间过去的活动；以及股票朋友之间的社交网络。社会网络分析将帮助研究人员测试现有的关于人们如何以及为什么参与股票友谊的想法，并了解这些原因在受经济和环境变化影响较大与影响较小的人群中是如何变化的。这项研究提供了一个独特的机会，不仅可以研究种群友谊如何缓冲经济风险，还可以研究种群友谊如何适应影响世界各地牧民的变化。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Human societies everywhere deal with adverse social and environmental conditions that put livelihoods at risk, but they also tend to develop traditions and institutions that help adapt to those conditions. In the American Southwest, for example, droughts and floods can threaten cattle ranchers. In response, ranchers have developed a social institution, called "neighboring," in which ranchers help neighbors in need. What would happen to institutions like neighboring, however, when the economy changes quickly? Around the world, herding can be a high-risk livelihood, with herd sizes routinely prone to sudden fluctuations due to drought, disease, and, in some countries, raids. Herders routinely have similar stock friendships, or networks of cattle lending and sharing. Some researchers suggest that stock friendships might be an example of informal insurance systems to protect against cattle losses, whereas others claim that they might be useful for accumulating cattle wealth and political influence among households over time.Aaron Lightner, under the supervision of Dr. Edward Hagen of Washington State University, investigates Maasai pastoralists in Tanzania, who have made their living by herding cattle for centuries. Recently, however, population growth, drought, and urbanization have forced many Maasai herders to turn to agriculture and cash economies, becoming less dependent on the high-risk business of herding cattle, a sudden, fundamental change to their local economy. This research will investigate how stock friendship institutions have adapted to the changing economy, collecting data on household-level income from cattle, agriculture, and other sources; partner preferences and reputations; past activity among stock friends; and social networks among stock friends. Social network analysis will help the researchers test existing ideas about how and why people are participating in stock friendships, and to understand how these reasons might vary among people who are highly impacted vs. less impacted by economic and environmental changes at the field site. This research provides a unique opportunity to investigate not only how stock friendships buffer economic risks, but also how stock friendships are adapting to changes that are affecting herders around the world.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.