Daniel J. Kruger

Fruit and Vegetable Intake among Urban Community Gardeners

OBJECTIVE To determine the association between household participation in a community garden and fruit and vegetable consumption among urban adults. DESIGN Data were analyzed from a cross-sectional random phone survey conducted in 2003. A quota sampling strategy was used to ensure that all census tracts within the city were represented. SETTING Flint, Michigan. PARTICIPANTS 766 adults. VARIABLES MEASURED Fruit and vegetable intake was measured using questionnaire items from the Behavioral Risk Factor Surveillance System. Household participation in a community garden was assessed by asking the respondent if he or she, or any member of the household, had participated in a community garden project in the last year. ANALYSIS Generalized linear models and logistic regression models assessed the association between household participation in a community garden and fruit and vegetable intake, controlling for demographic, neighborhood participation, and health variables. RESULTS Adults with a household member who participated in a community garden consumed fruits and vegetables 1.4 more times per day than those who did not participate, and they were 3.5 times more likely to consume fruits and vegetables at least 5 times daily. CONCLUSIONS AND IMPLICATIONS Household participation in a community garden may improve fruit and vegetable intake among urban adults.

An evolutionary life-history framework for understanding sex differences in human mortality rates.

Sex differences in mortality rates stem from genetic, physiological, behavioral, and social causes that are best understood when integrated in an evolutionary life history framework. This paper investigates the Male-to-Female Mortality Ratio (M:F MR) from external and internal causes and across contexts to illustrate how sex differences shaped by sexual selection interact with the environment to yield a pattern with some consistency, but also with expected variations due to socioeconomic and other factors.

Sexual Selection and the Male:Female Mortality Ratio:

This paper extends the evolutionary understanding of sex differences in mortality rates by quantifying and graphically examining the overall Male to Female Mortality Ratio (M:F MR) for 11 specific leading causes of death across age groups in the USA, over the course of the lifespan in 20 different countries, and across the past 70 years in 5 countries. The resulting quantitative descriptions of rates, trends, and the relative contributions of various proximate causes of death to the M:F MR provide an initial exploration of the risks associated with being male. This analysis also illustrates how sex differences shaped by sexual selection interact in complex ways with multiple aspects of culture and environment to yield a pattern that has some consistency across decades and societies, but also has variations arising from differences among cohorts and cultures. The results confirmed our expectations of higher mortality rates for men than for women, especially in early adulthood, where three men died for every woman who died. For external causes the ratios were even higher. Historical mortality data reflect an epidemiological transition in which discrepancies between male and female mortality rates increase as general mortality rates fall. Cross-national variation in the modern M:F MR further suggests a universal pattern that is influenced by cultural and environmental context. Being male is now the single largest demographic risk factor for early mortality in developed countries.

A User’s Manual

We created an online questionnaire, listed about 2,000 characters from 201 canonical British novels of the nineteenth and early twentieth centuries, and asked respondents to select individual characters and answer questions about them. Potential research participants were identified by scanning lists of faculty in hundreds of English departments worldwide and selecting specialists in nineteenth-century British literature, especially scholars specializing in the novel. Lists of English departments are available on the web, and most departments give a listing of faculty that contains information about their teaching and research interests. Invitations were also sent to multiple listservs dedicated to the discussion of Victorian literature or specific authors or groups of authors in our study. Approximately 519 respondents completed a total of 1,470 questionnaires on 435 characters from 134 novels. A copy of the questionnaire used in the study can be accessed at the following URL: http://http://www-personal.umich.edu /~kruger/carroll-survey.html. (The form is no longer active and will not be used to collect data.)

Evolution and altruism Combining psychological mediators with naturally selected tendencies

This study integrates psychological predictors of helping intentions and naturally selected tendencies enhancing inclusive fitness for a more comprehensive understanding of altruism. Psychological mediators of helping intentions, empathic concern and oneness, and psychological processes facilitating kin selection and reciprocal altruism were combined in a structural equation model to predict participants’ (N=643) intentions to perform a risky rescue behavior. The tendency for reciprocal altruism and kinship were the strongest predictors of rescue intentions. Confirming previous research, empathic concern made a significant but small contribution in predicting helping intentions. Proximate mechanisms currently in the psychological literature did not entirely account for the effect of kinship on helping intentions. D 2003 Elsevier Science Inc. All rights reserved.

Proper and dark heroes as DADS and CADS

Empirical tests described in this article support hypotheses derived from evolutionary theory on the perceptions of literary characters. The proper and dark heroes in British Romantic literature of the late eighteenth and early nineteenth centuries respectively represent long-term and short-term mating strategies. Recent studies indicate that for long-term relationships, women seek partners with the ability and willingness to sustain paternal investment in extended relationships. For short-term relationships, women choose partners whose features indicate high genetic quality. In hypothetical scenarios, females preferred proper heroes for long-term relationships. The shorter the relationship under consideration, the more likely women were to choose dark heroes as partners.

Towards the development of an evolutionarily valid domain-specific risk-taking scale

From an evolutionary perspective, human risk-taking behaviors should be viewed in relation to evolutionarily recurrent survival and reproductive problems. In response to recent calls for domain-specific measures of risk-taking, we emphasize the need of evolutionarily valid domains. We report on two studies designed to validate a scale of risky behaviors in domains selected from research and theory in evolutionary psychology and biology, corresponding to reoccurring challenges in the ancestral environment. Behaviors were framed in situations which people would have some chance of encountering in modern times. We identify five domains of risk-taking: between-group competition, within-group competition, mating and resource allocation for mate attraction, environmental risks, and fertility risks.

Is Risk Taking Used as a Cue in Mate Choice

More frequent risk taking among young men than women has been explained as a sexually selected trait, perhaps advertising male quality. We investigated this hypothesis in three studies. (1) Young men and women rated how attractive they would find it if a potential partner took various specific risks. A domain-specific risk inventory allowed us to distinguish whether risk taking is attractive generally or only in certain domains. Both sexes reported social and recreational risk taking as attractive (the latter not always significantly so), but other domains of risk taking as unattractive (ethics, gambling, and health) or neutral (investment). The sexes differed markedly little. Parallel studies in Germany and the United States yielded very similar results. (2) We asked subjects to predict how attractive the other sex would find it if the subject performed each risky behavior. Both sexes were rather accurate (which could be merely because they assume that the other sex feels as they do) and sex differences in attractive risk taking are not explicable by sex differences either in attraction or in beliefs about what others find attractive. However, our data could explain why unattractive risks are more often taken by men than women (men slightly underestimated the degree of unattractiveness of such risks, whereas U.S. women overestimated it, perhaps because they themselves found such risk taking more unattractive than did U.S. men). (3) Both members of 25 couples reported their likelihood of engaging in specific risky behaviors, their perception of these risks, and how attractive they would have found these behaviors in their partner. One hypothesis was that, for instance, a woman afraid of heights would be particularly impressed by a man oblivious to such risks. Instead we found positive assortment for risk taking, which might be explained by a greater likelihood of encountering people with similar risk attitudes (e.g. members of the same clubs) or a greater compatibility between such mates. Finally, contrary to the assumption that taking a low risk is likely to be less revealing of an individuals quality than taking a high risk, we found a strong negative relationship between the perceived riskiness of a behavior and how attractive it was judged.

Was That Cheating? Perceptions Vary by Sex, Attachment Anxiety, and Behavior

We generated an inventory of 27 interpersonal behaviors and examined the extent to which participants judged each behavior as cheating on a long-term partner. We predicted variation in these judgments based on participant sex and attachment insecurity. Ratings for items ranged considerably; participants rated sexual behaviors as most indicative of cheating, then erotic behaviors, followed by behaviors consistent with a romantic relationship, and then behaviors related to financial support. Women rated ten items higher than did men, and mens ratings were higher on a minor financial support item. Higher attachment anxiety was associated with higher ratings for 18 of 27 behaviors; higher attachment avoidance was associated with lower scores on five items and higher scores on one item. Principle Axis Factoring identified three dimensions; sexual interaction, behaviors indicating close relationships, and casual social interaction. We discuss these results using the framework of attachment theory and sex-specific mating strategies.

Male Scarcity is Differentially Related to Male Marital Likelihood across the Life Course

If marriage markets were only subject to the influences of numerical supply and demand, one would expect that the scarcer sex in a population would have a greater proportion married. Previous research has demonstrated that when males are scarce, they are actually less likely to be married, presumably because their market scarcity enhances their short term mating success and decreases incentives for commitment. However, males in modern societies appear to shift from mating effort to parental investment across the life course. Also, women preferentially value indicators of phenotypic quality for short term relationships, and these signals may be increasingly difficult to display with progressive physiological senescence. We predicted that men in low sex ratio populations would use market scarcity to their advantage for mating effort when young, but would shift towards commitment strategies when older. Data from the 50 largest Metropolitan Statistical Areas in the USA confirmed that a female biased sex ratio was associated with a lower proportion of men married between ages 20 and 29, but a higher proportion of men married between ages 35 and 74.