Household Task Delegation Among High-Fertility Forager-Horticulturalists of Lowland Bolivia

Human kin cooperation is universal, leading researchers to label humans as “cooperative breeders.” Despite widespread interest in human cooperation, there has been no systematic study of how household economic decision making occurs. We document age and sex profiles of task delegation by parents to children ages 4–18 among Bolivian forager-horticulturalists. We test for sex differences in the probability of delegation and examine whether tasks are more likely delegated as household labor demand increases. We also test whether food acquisition tasks are more likely delegated to higher producers.We find mixed support for the prediction that girls are more likely delegated domestic and alloparenting tasks than boys (np173 children). Both sexes are more likely delegated tasks during rice harvest months; number of coresident young children is also associated with greater probability of delegated allocare, although the effect retains significance for girls only. For both sexes, father absence is associated with greater probability of delegation, particularly for food acquisition tasks. Children delegated rice harvesting achieve 45% higher mean daily caloric returns from harvesting than children not delegated harvesting. Our results therefore suggest that delegation increases household economic efficiency. We find mixed support for the hypothesis that delegation prepares children for sex-specific adult roles

From the Womb to the Tomb: The Role of Transfers in Shaping the Evolved Human Life History

Humans are the longest living and slowest growing of all primates. Although most primates are social, humans are highly cooperative and social in ways that likely co-evolved with the slow human life history. In this paper we highlight the role of resource transfers and non-material assistance within and across generations in shaping low human mortality rates. The use of complex cooperative strategies to minimize risk is a necessary precursor for selecting further reductions in mortality rate in late adulthood. In conjunction with changes in the age-profile of production, the impacts of resource transfers and other forms of cooperation on reducing mortality likely played an important role in selection on post-reproductive lifespan throughout human evolution. Using medical data and ethnographic interviews, we explore several types of common risks experienced by Tsimane forager-horticulturalists, and quantify the types and targets of aid. Our results illustrate the importance of transfers in several key domains and suggest that the absence of transfers would greatly increase human mortality rates throughout the life course

Skills, Division of Labor, and Economies of Scale Among Amazonian Hunters and South Indian Honey Collectors

In foraging and other productive activities, individuals make choices regarding whether and with whom to cooperate, and in what capacities. The size and composition of cooperative groups can be understood as a self-organized outcome of these choices, which are made under local ecological and social constraints. This article describes a theoretical framework for explaining the size and composition of foraging groups based on three principles: (1) the sexual division of labor; (2) the intergenerational division of labor; and (3) economies of scale in production. We test predictions from the theory with data from two field contexts: Tsimane\u27 game hunters of lowland Bolivia, and Jenu Kuruba honey collectors of South India. In each case, we estimate the impacts of group size and individual group members’ effort on group success. We characterize differences in the skill requirements of different foraging activities, and show that individuals participate more frequently in activities in which they are more efficient. We evaluate returns to scale across different resource types, and observe higher returns at larger group sizes in foraging activities (such as hunting large game) that benefit from coordinated and complementary roles. These results inform us that the foraging group size and composition are guided by the motivated choice of individuals on the basis of relative efficiency, benefits of cooperation, opportunity costs, and other social considerations

Does Market Integration Buffer Risk, Erode Traditional Sharing Practices and Increase Inequality? a Test Among Bolivian Forager-Farmers

Sharing and exchange are common practices for minimizing food insecurity in rural populations. The advent of markets and monetization in egalitarian indigenous populations presents an alternative means of managing risk, with the potential impact of eroding traditional networks. We test whether market involvement buffers several types of risk and reduces traditional sharing behavior among Tsimane Amerindians of the Bolivian Amazon. Results vary based on type of market integration and scale of analysis (household vs. village), consistent with the notion that local culture and ecology shape risk management strategies. Greater wealth and income were unassociated with the reliance on others for food, or on reciprocity, but wealth was associated with a greater proportion of food given to others (i.e., giving intensity) and a greater number of sharing partners (i.e., sharing breadth). Across villages, greater mean income was negatively associated with reciprocity, but economic inequality was positively associated with giving intensity and sharing breadth. Incipient market integration does not necessarily replace traditional buffering strategies but instead can often enhance social capital

Productivity Loss Associated with Functional Disability in a Contemporary Small-scale Subsistence Population

In comparative cross-species perspective, humans experience unique physical impairments with potentially large consequences. Quantifying the burden of impairment in subsistence populations is critical for understanding selection pressures underlying strategies that minimize risk of production deficits. We examine among forager-horticulturalists whether compromised bone strength (indicated by fracture and lower bone mineral density, BMD) is associated with subsistence task cessation. We also estimate the magnitude of productivity losses associated with compromised bone strength. Fracture is associated with cessation of hunting, tree chopping, and walking long distances, but not tool manufacture. Age-specific productivity losses from hunting cessation associated with fracture and lower BMD are substantial: ~397 lost kcals/day, with expected future losses of up to 1.9 million kcals (22% of expected production). Productivity loss is thus substantial for high strength and endurance tasks. Determining the extent to which impairment obstructs productivity in contemporary subsistence populations improves our ability to infer past consequences of impairment

Near-field diffraction of fs and sub-fs pulses: super-resolutions of NSOM in space and time

The near-field diffraction of fs and sub-fs light pulses by nm-size slit-type apertures and its implication for near-field scanning optical microscopy (NSOM) is analyzed. The amplitude distributions of the diffracted wave-packets having the central wavelengths in the visible spectral region are found by using the Neerhoff and Mur coupled integral equations, which are solved numerically for each Fourier's component of the wave-packet. In the case of fs pulses, the duration and transverse dimensions of the diffracted pulse remain practically the same as that of the input pulse. This demonstrates feasibility of the NSOM in which a fs pulse is used to provide the fs temporal resolution together with nm-scale spatial resolution. In the sub-fs domain, the Fourier spectrum of the transmitted pulse experiences a considerable narrowing that leads to the increase of the pulse duration in a few times. This imposes a limit on the simultaneous resolutions in time and space.Comment: 5 figure

Microwave properties of Nd_0.5Sr_0.5MnO_3: a key role of the (x^2-y^2)-orbital effects

Transmittance of the colossal magnetoresistive compound Nd_0.5Sr_0.5MnO_3 showing metal-insulator phase transition has been studied by means of the submm- and mm-wavelength band spectroscopy. An unusually high transparency of the material provided direct evidence for the significant suppression of the coherent Drude weight in the ferromagnetic metallic state. Melting of the A-type antiferromagnetic states has been found to be responsible for a considerable increase in the microwave transmission, which was observed at the transition from the insulating to the metallic phase induced by magnetic field or temperature. This investigation confirmed a dominant role of the (x^2-y^2)-orbital degree of freedom in the low-energy optical properties of Nd_0.5Sr_0.5MnO_3 and other doped manganites with planar (x^2-y^2)-orbital order, as predicted theoretically. The results are discussed in terms of the orbital-liquid concept.Comment: 8 pages, 3 figure

Supporting the Occupational Therapy Student in the Production and Dissemination of Systematic Reviews: An Interprofessional Collaboration among Librarians and Occupational Therapy Faculty

Objectives This poster describes the outcomes of a curriculum-based collaboration between librarians and OT faculty (‘collaboration’) to enhance graduate student skills for conducting a systematic review (SR); the collaboration included database instruction, bibliographic management software, and culminated in student presentations to healthcare practitioners for continuing education credit. Three outcome areas are discussed: impact of the collaboration on student satisfaction and perceived competence; characteristics of the included literature; and the dissemination of SR findings to healthcare practitioners. Methods Three librarians participated in the instruction and the institutional repository (Jefferson Digital Commons; JDC) deposits. A total of 132 students over a period of two years (2013-2014) completed the curriculum, engaging with librarians and OT faculty to iteratively build on skills. At the conclusion of their curriculum, the capstone presentations were recorded and made freely available through the JDC. Quantitative data were examined with descriptive statistics in SPSS, and qualitative data were thematically coded by hand: course evaluations, practitioner attendance, bibliographic evaluations of the systematic reviews, and download statistics from the institutional repository. Results Students reported on open-ended course evaluation questions that among the top three concepts learned was ‘how to conduct a replicable and effective search.’ On multiple answer questions 83.6% of students selected the ‘collaborative librarian-faculty lecture’ as among the most helpful lectures offered, and 78.2% selected ‘working with librarian staff and course mentors to develop a search strategy’ as highly rated among course activities. Bibliographic data were extracted from 22 of 28 capstone presentations available for analysis (2013-2014) in the institutional repository, which contained 305 citations from 157 journals. The average of age of included articles was 4.8 years (SD=4.2, Range=0-24). Among the top 10 cited journals were 2 occupational therapy, 5 rehabilitation, and 3 specialty. Overall health care practitioner attendance at student capstones from 2012-2014 was 323. JDC recordings (as of 1/6/2015) had been accessed from 25 different countries, and are located most frequently via Google, JDC, and GoogleScholar. The total number of views was 1,446, and the total number of hours viewed was 163 hours. Conclusions Librarian-faculty collaborations resulted in high student perception of competence to conduct systematic reviews, utilization of a broad variety of peer-reviewed journals, and enhanced dissemination of evidence

Inflammatory Bowel Disease Cause-specific Mortality: A Primer for Clinicians

Background: Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC) is perceived to harbor significant morbidity but limited excess mortality, thought to be driven by colon cancer, compared with the general population. Recent studies suggest mortality rates seem higher than previously understood, and there are emerging threats to mortality. Clinicians must be up to date and able to clearly convey the causes of mortality to arm individual patients with information to meaningfully participate in decisions regarding IBD treatment and maintenance of health. Methods: A MEDLINE search was conducted to capture all relevant articles. Keyword search included: “inflammatory bowel disease,” “Crohn's disease,” “ulcerative colitis,” and “mortality.” Results: CD and UC have slightly different causes of mortality; however, malignancy and colorectal cancer–associated mortality remains controversial in IBD. CD mortality seems to be driven by gastrointestinal disease, infection, and respiratory diseases. UC mortality was primarily attributable to gastrointestinal disease and infection. Clostridium difficile infection is an emerging cause of mortality in IBD. UC and CD patients have a marked increase in risk of thromboembolic disease. With advances in medical and surgical interventions, the exploration of treatment-associated mortality must continue to be evaluated. Conclusions: Clinicians should be aware that conventional causes of death such as malignancy do not seem to be as significant a burden as originally perceived. However, emerging threats such as infection including C. difficile are noteworthy. Although CD and UC share similar causes of death, there seems to be some differences in cause-specific mortality