Impediments to peace

While effective institutional practices are critical for the evolution of peace certain factors deter their effectiveness. In-group and out-group dynamics may make peace difficult between culturally distinct groups. Critical ecological conditions often lead to intractable conflict over resources. And within group conflicts of interest most prominently between generations may inhibit effective peace making.

Cross-cousin marriage among the Yanomamö shows evidence of parent-offspring conflict and mate competition between brothers

Marriage in many traditional societies often concerns the institutionalized exchange of reproductive partners among groups of kin. Such exchanges most often involve cross-cousins-marriage with the child of a parent's opposite-sex sibling-but it is unclear who benefits from these exchanges. Here we analyze the fitness consequences of marrying relatives among the Yanomamö from the Amazon. When individuals marry close kin, we find that (i) both husbands and wives have slightly lower fertility; (ii) offspring suffer from inbreeding depression; (iii) parents have more grandchildren; and (iv) siblings, especially brothers, benefit when their opposite-sex siblings marry relatives but not when their same-sex siblings do. Therefore, individuals seem to benefit when their children or opposite-sex siblings marry relatives but suffer costs when they, their parents, or same-sex siblings do. These asymmetric fitness outcomes suggest conflicts between parents and offspring and among siblings over optimal mating strategies. Parental control of marriages is reinforced by cultural norms prescribing cross-cousin marriage. We posit that local mate competition combined with parental control over marriages may escalate conflict between same-sex siblings who compete over mates, while simultaneously forging alliances between opposite-sex siblings. If these relationships are carried forward to subsequent generations, they may drive bilateral cross-cousin marriage rules. This study provides insights into the evolutionary importance of how kinship and reciprocity underlie conflicts over who controls mate choice and the origins of cross-cousin marriage prescriptions.

Human grooming in comparative perspective: People in six small-scale societies groom less but socialize just as much as expected for a typical primate

OBJECTIVES

Grooming has important utilitarian and social functions in primates but little is known about grooming and its functional analogues in traditional human societies. We compare human grooming to typical primate patterns to test its hygienic and social functions.

MATERIALS AND METHODS

Bayesian phylogenetic analyses were used to derive expected human grooming time given the potential associations between grooming, group size, body size, terrestriality, and several climatic variables across 69 primate species. This was compared against observed times dedicated to grooming, other hygienic behavior, and conversation among the Maya, Pumé, Sanöma, Tsimane', Yanomamö, and Ye'kwana (mean number of behavioral scans = 23,514).

RESULTS

Expected grooming time for humans was 4% (95% Credible Interval = 0.07%-14%), similar to values observed in primates, based largely on terrestriality and phylogenetic signal (mean λ = 0.56). No other covariates strongly associated with grooming across primates. Observed grooming time across societies was 0.8%, lower than 89% of the expected values. However, the observed times dedicated to any hygienic behavior (3.0%) or "vocal grooming," that is conversation (7.3%), fell within the expected range.

CONCLUSIONS

We found (i) that human grooming may be a (recent) phylogenetic outlier when defined narrowly as parasite removal but not defined broadly as personal hygiene, (ii) there was no support for thermoregulatory functions of grooming, and (iii) no support for the "vocal grooming" hypothesis of language having evolved as a less time-consuming means of bonding. Thus, human grooming reflects decreased hygienic needs, but similar social needs compared to primate grooming.

Does attending general practice prior to the emergency department change patient outcomes? A descriptive, observational study of one central London general practice

BACKGROUND

The challenge of keeping Emergency Department (ED) attendances down continues and timely access to general practice (GP) is often portrayed as a potential solution.

SETTING

One London general practice (registered population = 4900).

QUESTION

Does seeing a GP before attending the ED affect the outcome of a patient's ED care?

METHODS

Routine clinical data were extracted using SystmOne primary care computer system for all registered patients with an ED attendance between 1 October 2014 and 31 September 2015. The scanned discharge summaries from the ED and GP notes were reviewed and outcome measures extracted.

RESULTS

227 patients (121 female; 104 male) attended the ED. The most common presentation was abdominal pain (n = 11). 25% of patients had seen (n = 50), or contacted by phone (n = 6), a GP about the same presenting complaint before attending the ED. Of those, 73% (n = 41/56) were referred to the ED and 49% (n = 20/41) were admitted versus 33% (n = 60/184) who self-presented (statistically significant, p = 0.05). An additional 32% of those who saw the GP first (n = 13/41) received specialist ED treatment.

DISCUSSION/CONCLUSION

Only 25% of patients see their GP prior to attending the ED. The majority of patients who were referred by their GP required admission or specialised ED treatment. It remains unclear why the majority of patients did not choose to contact their GP prior to attending the ED, despite urgent appointments being offered; research into patients' health beliefs in this group is required for greater understanding.

Is Male Androphilia a Context-Dependent Cross-Cultural Universal?

The cross-cultural ethnographic literature has traditionally used the label male "homosexuality" to describe sexual relationships between biological males without considering whether or not the concept encompasses primary sexual attraction to adult males. Although male androphilia seems to be found in all national populations, its universal existence in tribal populations has been questioned. Our goal is to review previous cross-cultural classifications and surveys of male same sex behavior to present a system that does justice to its varied expressions, especially as it is informed by contemporary sexuality research. Previous comparative research does not effectively distinguish male same sex behavior from male androphilia. Using the standard cross-cultural sample (SCCS) as a sampling frame and the ethnographic sources in the human relations area files and elsewhere, we present distributional data on various forms of male same sex behavior. The SCCS is useful because it is designed to be representative of all historically known social formations and the sample is designed to reduce similarities as a consequence of common descent or historical origin as well as reduce the probability of diffusion of sociocultural practices from one culture to another. Our results show that male same sex behavior as well as male androphilia is much more common than previously estimated in the SCCS. With our findings, we make an argument that male androphilia is a context-dependent cross-cultural universal.

A Problematic Test of the Kin Selection Hypothesis Among the Urak-Lawoi of Ko Lipe, Thailand: Commentary on Camperio Ciani, Battaglia, and Liotta (2015)

Camperio Ciani et al. argued that the Urak-Lawoi people of Ko Lipe island live in a "traditional," "subsistence primitive society" reminiscent of the "ancestral" human past and that their socio-cultural situation is "remarkably similar" to Samoa. On this basis, they asserted that the Ko Lipe Urak-Lawoi are an appropriate population for determining the role that kin selection played in the evolution of male androphilia. The purpose of this commentary is to outline some of our concerns with this characterization and with the statistical analyses conducted by Camperio Ciani et al. in their study of the Urak-Lawoi.

Women's work, child care, and helpers-at-the-nest in a hunter-gatherer society

Considerable research on helpers-at-the-nest demonstrates the positive effects of firstborn daughters on a mother's reproductive success and the survival of her children compared with women who have firstborn sons. This research is largely restricted to agricultural settings. In the present study we ask: "Does 'daughter first' improve mothers' reproductive success in a hunting and gathering context?" Through an analysis of 84 postreproductive women in this population we find that the sex of the first- or second-born child has no effect on a mother's fertility or the survival of her offspring. We conclude that specific environmental and economic factors underlay the helpers-at-the-nest phenomenon.

Growth rates and life histories in twenty-two small-scale societies

This study investigates variation in body growth (cross-sectional height and weight velocity) among a sample of 22 small-scale societies. Considerable variation in growth exists among hunter-gatherers that overlaps heavily with growth trajectories present in groups focusing more on horticulture. Intergroup variation tends to track environmental conditions, with societies under more favorable conditions displaying faster growth and earlier puberty. In addition, faster/earlier development in females is correlated with higher mortality. For example, African "Pygmies," Philippine "Negritos," and the Hiwi of Venezuela are characterized by relatively fast child-juvenile growth for their adult body size (used as a proxy for energetic availability). In these societies, subadult survival is low, and puberty, menarche, and first reproduction are relatively early (given their adult body size), suggesting selective pressure for accelerated development in the face of higher mortality. In sum, the origin and maintenance of different human ontogenies may require explanations invoking both environmental constraints and selective pressures.