The role of cultural transmission in human demographic change: an age-structured model.

Human populations vary demographically with population sizes ranging from small groups of hunter-gatherers with less than fifty individuals to vast cities containing many millions. Here we investigate how the cultural transmission of traits affecting survival, fertility, or both can influence the birth rate, age structure, and asymptotic growth rate of a population. We show that the strong spread of such a trait can lead to a demographic transition, similar to that experienced in Europe in the late 19th and early 20th centuries, without using ecological or economic optimizing models. We also show that the spread of a cultural trait that increases fertility, but not survival, can cause demographic change similar to the 'Neolithic demographic transition': a period of increased population growth that is thought to have accompanied the transition from hunter-gatherer to agricultural lifestyles. We investigate the roles of vertical, oblique, and horizontal learning of such a trait in this transition and find that compared to vertical learning alone, horizontal and oblique learning can accelerate the trait's spread, lead to faster population growth, and increase its equilibrium frequency.

The evolution of teaching.

Teaching, alongside imitation, is widely thought to underlie the success of humanity by allowing high-fidelity transmission of information, skills, and technology between individuals, facilitating both cumulative knowledge gain and normative culture. Yet, it remains a mystery why teaching should be widespread in human societies but extremely rare in other animals. We explore the evolution of teaching using simple genetic models in which a single tutor transmits adaptive information to a related pupil at a cost. Teaching is expected to evolve where its costs are outweighed by the inclusive fitness benefits that result from the tutor's relatives being more likely to acquire the valuable information. We find that teaching is not favored where the pupil can easily acquire the information on its own, or through copying others, or for difficult to learn traits, where teachers typically do not possess the information to pass on to relatives. This leads to a narrow range of traits for which teaching would be efficacious, which helps to explain the rarity of teaching in nature, its unusual distribution, and its highly specific nature. Further models that allow for cumulative cultural knowledge gain suggest that teaching evolved in humans because cumulative culture renders otherwise difficult-to-acquire valuable information available to teach.

How copying affects the amount, evenness and persistence of cultural knowledge: insights from the social learning strategies tournament.

Darwinian processes should favour those individuals that deploy the most effective strategies for acquiring information about their environment. We organized a computer-based tournament to investigate which learning strategies would perform well in a changing environment. The most successful strategies relied almost exclusively on social learning (here, learning a behaviour performed by another individual) rather than asocial learning, even when environments were changing rapidly; moreover, successful strategies focused learning effort on periods of environmental change. Here, we use data from tournament simulations to examine how these strategies might affect cultural evolution, as reflected in the amount of culture (i.e. number of cultural traits) in the population, the distribution of cultural traits across individuals, and their persistence through time. We found that high levels of social learning are associated with a larger amount of more persistent knowledge, but a smaller amount of less persistent expressed behaviour, as well as more uneven distributions of behaviour, as individuals concentrated on exploiting a smaller subset of behaviour patterns. Increased rates of environmental change generated increases in the amount and evenness of behaviour. These observations suggest that copying confers on cultural populations an adaptive plasticity, allowing them to respond to changing environments rapidly by drawing on a wider knowledge base.

Why copy others? Insights from the social learning strategies tournament.

Social learning (learning through observation or interaction with other individuals) is widespread in nature and is central to the remarkable success of humanity, yet it remains unclear why copying is profitable and how to copy most effectively. To address these questions, we organized a computer tournament in which entrants submitted strategies specifying how to use social learning and its asocial alternative (for example, trial-and-error learning) to acquire adaptive behavior in a complex environment. Most current theory predicts the emergence of mixed strategies that rely on some combination of the two types of learning. In the tournament, however, strategies that relied heavily on social learning were found to be remarkably successful, even when asocial information was no more costly than social information. Social learning proved advantageous because individuals frequently demonstrated the highest-payoff behavior in their repertoire, inadvertently filtering information for copiers. The winning strategy (discountmachine) relied nearly exclusively on social learning and weighted information according to the time since acquisition.

Measurement of the Ec.m. = 184 keV resonance strength in the 26gAl (p, gamma)27 Si reaction.

The strength of the Ec.m. = 184 keV resonance in the 26gAl(p, gamma)27 reaction has been measured in inverse kinematics using the DRAGON recoil separator at TRIUMF's ISAC facility. We measure a value of omega gamma = 35 +/- 7 microeV and a resonance energy of Ec.m. = 184 +/- 1 keV, consistent with p-wave proton capture into the 7652(3) keV state in 27Si, and discuss the implications of these values for 26GAl nucleosynthesis in typical oxygen-neon white-dwarf novae.

Abundance and characteristics of the recreational water quality indicator bacteria Escherichia coli and enterococci in gull faeces.

AIMS: To evaluate the numbers and selected phenotypic and genotypic characteristics of the faecal indicator bacteria Escherichia coli and enterococci in gull faeces at representative Great Lakes swimming beaches in the United States. METHODS AND RESULTS: E. coli and enterococci were enumerated in gull faeces by membrane filtration. E. coli genotypes (rep-PCR genomic profiles) and E. coli (Vitek GNI+) and enterococci (API rapid ID 32 Strep and resistance to streptomycin, gentamicin, vancomycin, tetracycline and ampicillin) phenotypes were determined for isolates obtained from gull faeces both early and late in the swimming season. Identical E. coli genotypes were obtained only from single gull faecal samples but most faecal samples yielded more than one genotype (median of eight genotypes for samples with 10 isolates). E. coli isolates from the same site that clustered at >/=85% similarity were from the same sampling date and shared phenotypic characteristics, and at this similarity level there was population overlap between the two geographically isolated beach sites. Enterococcus API(R) profiles varied with sampling date. Gull enterococci displayed wide variation in antibiotic resistance patterns, and high-level resistance to some antibiotics. CONCLUSIONS: Gull faeces could be a major contributor of E. coli (10(5)-10(9) CFU g(-1)) and enterococci (10(4)-10(8) CFU g(-)1) to Great Lakes recreational waters. E. coli and enterococci in gull faeces are highly variable with respect to their genotypic and phenotypic characteristics and may exhibit temporal or geographic trends in these features. SIGNIFICANCE AND IMPACT OF THE STUDY: The high degree of variation in genotypic or phenotypic characteristics of E. coli or enterococci populations within gull hosts will require extensive sampling for adequate characterization, and will influence methods that use these characteristics to determine faecal contamination sources for recreational waters.

Attitudes of maternal-fetal specialists concerning maternal-fetal surgery.

OBJECTIVE: We examined the attitudes of members of the Society for Maternal-Fetal Medicine regarding the clinical, scientific, ethical, and policy issues in maternal-fetal surgery. STUDY DESIGN: A 43-question survey was distributed to all members of the Society for Maternal-Fetal Medicine. Two mailings and one electronic mail reminder were sent, each with instructions to submit the survey either via US mail or the Internet. The survey included questions in six categories: physician demographic data, experience with maternal-fetal surgery, views on innovative therapies, scientific validation of currently used and proposed procedures, ethical issues, and future directions in public policy. RESULTS: Of the 1639 United States members sent questionnaires, 943 replied (response rate = 59%). Forty-seven percent had referred patients for open fetal surgery for nonlethal conditions, and 69% believed physicians were obligated to inform patients of this option. Seventy-eight percent believed that innovative therapies should be performed only under institutional review board-approved protocols. Although the majority of respondents believed that certain proposed benefits of open fetal surgery for myelomeningocele could offset the risks, the majority (56%) also indicated that the procedure has not been validated. Fifty-seven percent believed that a moratorium should be imposed on open fetal surgery for nonlethal conditions, such as myelomeningocele, until a multicenter-controlled clinical trial is completed. CONCLUSIONS: The use of maternal-fetal surgery for nonlethal conditions is highly controversial. The majority of maternal-fetal specialists we surveyed support further research before such procedures are integrated into clinical practice.

Reproductive and contraceptive attitudes as predictors of condom use among women in an HIV prevention intervention.

This study prospectively evaluates the effect of childbearing motivation and contraceptive attitudes on consistency of condom use among at-risk women enrolled in an HIV prevention intervention. Women (age 15-40, 85% African-American) were recruited from homeless shelters, drug treatment facilities, and public housing developments and assigned to standard or enhanced intervention conditions. Among the eligible study group of nonsterilized women with a main partner (n = 312), 24.4% wanted to have a baby at baseline; 43.5% believed their partner wanted them to have a baby. Women who reported a desire for a baby, compared to all others, were less likely to be at a higher level of condom consistency six months later (OR = 0.66; .48-.90). Women who perceived partner support for contraceptive use showed a higher level of condom consistency (OR = 1.20; 1.03-1.41) at 6-month follow-up. Many women in this study wanted to have a baby and this desire interfered with subsequent consistency of condom use. We also found that condom use increased toward consistency of use among women whose partner supported contraceptive use. HIV prevention interventions should include screening for reproductive motivation, so that prevention messages can be tailored to the realities of women's lives. Women who want a baby can be educated about disease prevention in the context of pregnancy planning and linked with appropriate services. Women who want to avoid childbearing can be given messages that emphasize the contraceptive benefits of condom use and that help strengthen partner support.

Long-term effectiveness of a peer-based intervention to promote condom and contraceptive use among HIV-positive and at-risk women.

OBJECTIVE: The authors used data from a larger study to evaluate the long-term effects of a peer advocate intervention on condom and contraceptive use among HIV-infected women and women at high risk for HIV infection. METHODS: HIV-infected women in one study and women at high risk for HIV infection in a second study were selected from the Women and Infants Demonstration Project and assigned to a standard or an enhanced HIV prevention treatment group. The enhanced intervention included support groups and one-on-one contacts with peer advocates tailored to clients' needs. The authors interviewed women at baseline and at 6-, 12- and 18-months, and measured changes in consistency of condom and contraceptive use and in self-efficacy and perceived advantages and disadvantages of condom and contraceptive use. RESULTS: Of HIV-infected women, the enhanced group had improved consistency in condom use, increased perceived advantages of condom use, and increased level of self-efficacy compared with the standard group. Of women at risk, the enhanced intervention group at six months maintained consistent condom use with a main partner and perceived more benefit of condom use compared with the standard group. These differences diminished at 12 months. CONCLUSIONS: The enhanced intervention was generally effective in the HIV+ study. In the at-risk study, however, intervention effects were minimal and short-lived. Factors related to the theory, intervention design, and sample characteristics help explain these differences.

Women living with HIV: disclosure, violence, and social support.

This paper describes the frequency of women's disclosure of their HIV status, examines the extent to which they experience adverse social and physical consequences when others learn they are infected, and analyzes correlates of these negative outcomes. There were 257 HIV-positive women between the ages of 18 and 44, recruited from HIV/AIDS primary care clinics and from community sites, who completed a face-to-face interview. Women in the sample were 33 years old on average; 92% were African-American; 54% had less than 12 years of education; 56% had used intravenous drugs; and 30% knew they were HIV positive for 5 or more years. There were 97% who disclosed their HIV status; 64% told more than 5 people. Negative consequences associated with others knowing they were HIV-positive were reported by 44%, most commonly the loss of friends (24%), being insulted or sworn at (23%), and being rejected by family (21%). There were 10 women (4%) who reported being physically or sexually assaulted as a result of their being HIV positive, and 16% reported having no one they could count on for money or a place to stay. Violence was widespread in this sample, with 62% having experienced physical or sexual violence, including sexual abuse or rape (27%), being beaten up (34%), and weapon-related violence (26%). Logistic regression analysis indicated that women with a history of physical and sexual violence were significantly more likely to experience negative social and physical consequences when their infection became known to others, adjusting for age and the number of people women had disclosed to, both of which were only marginally significant. Partner notification policies and support programs must be responsive to the potential negative consequences associated with others learning that a woman is HIV positive. The high rates of historical violence in the lives of women living with HIV underscore the need for routine screening and intervention for domestic violence in all settings that provide health care to HIV-positive women.

Psychiatric inferences from data on psychologic/psychiatric symptoms in multiple chemical sensitivities syndrome.

When abnormal psychologic/psychiatric symptom data are obtained on personality tests or psychiatric interviews administered to patients who report symptoms of Multiple Chemical Sensitivities Syndrome, investigators typically attribute these to either psychiatric traits or to psychogenic origins of illness. The primary purpose of these studies was the evaluation of the plausibility of nonpsychiatric explanations of psychologic/psychiatric symptom data. In Study 1, patients with Multiple Chemical Sensitivities Syndrome used the Minnesota Multiphasic Personality Inventory 2 (MMPI-2) to describe which items had changed after they developed the condition. In Study 2, three diverse groups of professionals predicted which items on the MMPI-2 might change after a mentally healthy person developed the Syndrome or a condition resembling it. In Study 3, a second sample of Multiple Chemical Sensitivities Syndrome patients completed the MMPI-2 and other questionnaires by mail, which allowed the authors to ascertain whether these patients showed more or different psychopathology than was described by patients and hypothesized by professionals. Data from Study 1 patient informants indicated that developing the syndrome might result in a psychopathological MMPI-2 profile, characterized by abnormal Hypochondriasis and Hysteria scale scores. Professionals in Study 2 showed a consensus about hypothesized MMPI-2 changes following the development of the syndrome. These changes likely elevated the Hypochondriasis, Hysteria, Psychasthenia, Depression, and Schizophrenia scale scores. In Study 3, the patients taking the MMPI-2 showed elevations on the Hypochondriasis, Hysteria, Depression (women only), and Schizophrenia scales. Abnormal scores were associated closely with greater severity of illness and greater adjustment to illness. The strategy of administering psychometric tests to ill populations for the purposes of evaluating psychiatric illness or traits, and/or psychogenic origins of illness was shown to be potentially misleading.

Can 40 seconds of compassion reduce patient anxiety?

PURPOSE: To use a standardized videotape stimulus to assess the effect of physician compassion on viewers' anxiety, information recall, treatment decisions, and assessment of physician characteristics. PARTICIPANTS AND METHODS: One hundred twenty-three healthy female breast cancer survivors and 87 women without cancer were recruited for this study. A randomized pretest/posttest control group design with a standardized videotape intervention was used. Participants completed the State-Trait Anxiety Inventory (STAI), an information recall test, a compassion rating, and physician attribute rating scales. RESULTS: Women who saw an "enhanced compassion" videotape rated the physician as warmer and more caring, sensitive, and compassionate than did women who watched the "standard" videotape. Women who saw the enhanced compassion videotape were significantly less anxious after watching it than the women in the other group. Nevertheless, information recall was relatively low for both groups, and enhanced compassion did not influence patient decisions. Those who saw the enhanced compassion videotape rated the doctor significantly higher on other positive attributes, such as wanting what was best for the patient and encouraging the patient's questions and involvement in decisions. CONCLUSION: The enhanced compassion segment was short, simple, and effective in decreasing viewers' anxiety. Further research is needed to translate these findings to the clinical setting, where reducing patient anxiety is a therapeutic goal.

Distribution along a stages-of-behavioral-change continuum for condom and contraceptive use among women accessed in different settings. Prevention of HIV in Women and Infants Demonstration Projects.

The numbers of women of childbearing age in the US with HIV and AIDS from heterosexual transmission continues to rise. Behavioral interventions remain the best means of preventing transmission of HIV. Program planners often implement interventions to promote behavioral change in a wide range of settings such as family planning or sexually transmitted disease clinics, drug treatment facilities, or medical facilities that serve high risk and HIV positive women. Women recruited in different types of settings, however, may differ with respect to their experience with, attitudes toward, and willingness to use condoms and contraception. Such differences should be considered when tailoring interventions to the populations being served. We examined the readiness to use condoms and contraception among 3784 women in four cities recruited in three different types of settings: community, facilities not targeted to HIV positive women and medical facilities for HIV positive populations. Readiness to use condoms or contraception was measured using The Transtheoretical Model of Change. Women reported being in different stages along the continuum of condom and contraceptive use in the three settings. A greater proportion of women in the HIV-facility, 45%, had used condoms consistently for the previous 6 months compared to women in the other two settings (12% and 11%). Similarly, variation across settings was seen for contemplation of consistent contraceptive use to prevent unintended pregnancies. The variability in the distribution of condom and contraceptive use across settings underscores the importance of assessing the readiness for the behavior change and designing interventions that meet the specific needs of the populations being served.

Validation of a European message standard for electronic health records.

A European Standard message for communication of the contents of Electronic Health Records is currently at a late stage in development and is due to be adopted during 1999. This paper reports on the development and content of this message and on current work to clinically validate this message. The validation process involves a new method based on an instantiation of the proposed message in the Extensible Mark-up Language. This method allows the message to be viewed and compared with the same record on the source system.

Processes of change in the adoption of consistent condom use.

Descriptions of reproductive and sexual behavior were obtained from interviews with a convenience sample of women at risk of HIV infection or transmission to assess whether the processes of change (POC) constructs from the Transtheoretical Model apply to women's explanations of condom behavior change. Participants were recruited from public housing, drug treatment centers, homeless shelters, and other sources. Interviews with 45 women were selected for analysis based on criteria of condom behavior change and narrative richness. In phase I, POC constructs were identified in women's statements regarding condom behavior change, using an a priori coding scheme. In phase II, text passages for each POC were examined for the range of topics addressed and the POC's perceived function in condom use adoption. Results show that each POC was identified at least once and that all respondents made statements that matched at least two POCs. Only 4 percent of 400 text segments did not fit a POC category. POC constructs appear to be integral components of the strategies women in this study used to progress toward consistent condom use with male partners. Interventions that promote condom use may be strengthened by using POC constructs as a basis for service delivery.

Coping with the physical and psychosocial sequelae of bone marrow transplantation among long-term survivors.

We used a situation-specific approach to investigate common problems and associated coping processes among long-term survivors of bone marrow transplantation (BMT). Surveys were returned by 156 of the 191 (82%) eligible BMT survivors. Work and finance problems were endorsed relatively infrequently by respondents; physical problems and existential concerns were much more common. Problem occurrence was significantly related to demographic and treatment variables. The choice of coping mechanisms was related to the type of problem being faced: Significant effects were observed for four coping mechanisms from the COPE Inventory-active coping, suppression of competing activities, restraint, and acceptance. The differences were between one type of problem, infertility concern, and one or more of three other categories of problems (other physical problems, existential concerns, and work/finance problems) nominated by survivors. Some methodological considerations and directions for future research are outlined.