Female-biased parental investment is unusual but not unknown in human societies. Relevant explanatory models include Fisher’s principle, the Trivers-Willard model, local mate and resource competition and enhancement, and economic rational actor models. Possible evidence of female-biased parental investment includes sex ratios, mortality rates, parents’ stated preferences for offspring of one sex, and direct and indirect measurements of actual parental behavior. Possible examples of female-biased parental investment include the Mukogodo of Kenya, the Ifalukese of Micronesia, the Cheyenne of North America, the (...) Herero of southern Africa, the Kanjar of south Asia, the Mundugumor of New Guinea, contemporary North America, and historical Germany, Portugal, and the United States. (shrink)

Rappaport's comment includes several errors. First, he conflates manipulation and deceit. Second, he confuses the rationalism of the evolutionary biological analysis of organisms with the rationalism (or lack thereof) of the motivational and cognitive structures of the organisms under study. Third, his moralistic judgment of my focus on manipulation implies that scientists should not only not explore but should also suppress such unsettling ideas. We will make little progress in understanding morality and in fostering truly moral behavior if we refuse (...) to acknowledge that moralistic statements may sometimes, and perhaps even often, be used in a manipulative way. (shrink)

Intelligent design, though unnecessary in the study of biological evolution, is essential to the study of cultural evolution. However, the intelligent designers in question are not deities or aliens but rather humans going about their lives. The role of intentionality in cultural evolution can be elucidated through the addition of signaling theory to the framework outlined in the target article. (Published Online November 9 2006).

The relationship between parents' stated sex preferences for children and actual parental behaviour towards sons and daughters is examined among the Mukogodo, a group of traditional pastoralists in rural Kenya. Although their cultural values are male-centred and they tend to express a preference for sons, Mukogodo parents actually appear to be more solicitous of daughters, and the Mukogodo have a strongly female-biased childhood sex ratio. Studies of stated sex preferences should therefore be coupled with attempts to assess actual parental investment (...) in sons and daughters. (shrink)

Previous research has shown that the qualities of nuptial gifts among nonhumans and marriage-related property transfers in human societies such as bridewealth and dowry covary with aspects of mate quality. This article explores this issue for another type of marriage-related property transfer: engagement rings. We obtained data on engagement ring costs and other variables through a mail survey sent to recently married individuals living in the American Midwest. This article focuses on survey responses regarding rings that were purchased by men (...) acting alone and using only their own funds who then presented the rings while making surprise proposals of marriage (n = 127). Men marrying younger women spent more on rings, as did men who earned more money and whose fiancées earned more money. These findings suggest that the amounts spent on engagement rings, like bridewealth and dowry payments in other societies, reflect aspects of both male and female mate quality. (shrink)

To better understand risk management and mutual aid among American ranchers, we interviewed and mailed a survey to ranchers in Hidalgo County, New Mexico, and Cochise County, Arizona, focusing on two questions: When do ranchers expect repayment for the help they provide others? What determines ranchers’ degrees of involvement in networks of mutual aid, which they refer to as “neighboring”? When needs arise due to unpredictable events, such as injuries, most ranchers reported not expecting to be paid back for the (...) help they provide. When help is provided for something that follows a known schedule or that can be scheduled, such as branding, most ranchers did expect something in return for the help they provide. This pattern makes sense in light of computational modeling that shows that transfers to those in need without expectations of repayment pool risk more effectively than transfers that create debt. Ranchers reported helping other ranchers more often when they belonged to more religious and civic organizations, when they owned larger ranches, when they relied less on ranch vs. other income, and when they had more relatives in the area. Operators of midsize ranches reported helping other ranchers more frequently than did those on smaller and larger ranches. None of our independent variables predicted how many times ranchers reported receiving help from other ranchers. Although ranch culture in the American West is often characterized by an ethic of individualism and independence, our study suggests that this ethic stands alongside an ethic of mutual aid during times of need. (shrink)

Falk's contribution to a continuity theory of the origins of language would be complemented by an account of the origins of displaced reference, a key characteristic distinguishing human language from animal signaling systems. Because deception is one situation in which nonhumans may use signals in the absence of their referents, deception may have been the starting point for displaced reference.

We suggest that there are two coordination games when it comes to understanding kin terminology. Jones' article focuses on the linguistic coordination inherent in developing meaningful kin terminologies, alluding briefly to the benefits of these kin terminologies for coordination in other domains. We enhance Jones' discussion by tracing the links between the structure of kin terminologies and their functions.

Smaldino argues that evolutionary theories of social behavior do not adequately explain the emergence of group-level traits, including differentiation of roles and organized interactions among individuals. We find Smaldino's account to be commendable but incomplete. Our commentary focuses on a simple question that has not been adequately addressed: What is a group?