Just do it

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28510/1/0000307.pd

Parental investment by sex on ifaluk

Trivers and Willard (Science 179;90-92, 1973) predict that where investment by parents in good condition increases the fitness of sons more than that of their sisters, while the opposite is true of parents in poor condition, parents with much to invest will favor sons, while those with little will favor daughters. Patterns of parent-child association on Ifaluk atoll are consistent with this prediction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26325/1/0000412.pd

Which humans behave adaptively, and why does it matter?

There has long been debate about the relevance of evolutionary theory to the study of humans. To many of us, however, the debate has shifted from whether to proceed with an evolutionary approach to how to proceed. Increasingly, it has been argued that studies of the current reproductive function of human traits make little or no contribution to the understanding of the psyche (e.g., Symons 1989). Here, on the basis of arguments about the relationship between an adaptation and an adaptive outcome, and a review of studies that assess current adaptiveness, I argue to the contrary that knowledge of the contexts in which people do or do not behave adaptively provides important information about the nature of the mechanisms that comprise the human psyche. In particular, studies that indicate that people behave adaptively in at least some contemporary environments cast doubt on many nonevolutionary constructions of human nature, and can be used now to distinguish alternative evolutionary constructions that are at odds over many issues pentaining to the human psyche's ontogeny and evolutionary background, especially the extent to which the human psyche is general purpose.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28505/1/0000302.pd

Those who can do: Wealth, status, and reproductive success on Ifaluk

People everywhere require and therefore value resources. On Ifaluk, an atoll in the Western Carolines, salaried men, men of high status, and adults with living parents have more resources than other members of the population. The issue addressed here is whether differential success at acquiring resources leads to differential reproductive success. Analysis of Ifalukese age-specific fertility rates indicates the following: 1. 1. Men who receive or once received salaries have greater reproductive success than any other category of men. Reasons include that they begin reproducing at especially young ages, have shorter than average birth intervals, and only rarely fail to reproduce altogether.2. 2. As a group, men with high status (chiefs, and their advisors and probable successors) have greater reproductive success than all never-salaried others. Reasons include shorter than average birth intervals and a somewhat lower than average chance of failing to reproduce altogether.3. 3. Individuals with longer-living parents achieve higher than average lifetime reproductive success.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25828/1/0000391.pd