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Evolutionary dynamics of culturally transmitted, fertility-reducing traits.

ABSTRACT: Human populations in many countries have undergone a phase of demographic transition, characterized by a major reduction in fertility at a time of increased resource availability. A key stylized fact is that the reduction in fertility is preceded by a reduction in mortality and a consequent increase in population density. Various theories have been proposed to account for the demographic transition process, including maladaptation, increased parental investment in fewer offspring, and cultural evolution. None of these approaches, including formal cultural evolutionary models of the demographic transitions, have addressed a possible direct causal relationship between a reduction in mortality and the subsequent decline in fertility. We provide mathematical models in which low mortality favours the cultural selection of low-fertility traits. This occurs because reduced mortality slows turnover in the model, which allows the cultural transmission advantage of low-fertility traits to outrace their reproductive disadvantage. For mortality to be a crucial determinant of outcome, a cultural transmission bias is required where slow reproducers exert higher social influence. Computer simulations of our models that allow for exogenous variation in the death rate can reproduce the central features of the demographic transition process, including substantial reductions in fertility within only one to three generations. A model assuming continuous evolution of reproduction rates through imitation errors predicts fertility to fall below replacement levels if death rates are sufficiently low. This can potentially explain the very low preferred family sizes in Western Europe.

SUBMITTER: Wodarz D

PROVIDER: S-EPMC7211447 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundDespite available evidence-based interventions that decrease health disparities, these interventions are often not implemented. Northwestern Medicine's® Hispanic Kidney Transplant Program (HKTP) is a culturally and linguistically competent intervention designed to reduce disparities in living donor kidney transplantation (LDKT) among Hispanics/Latinos. The HKTP was introduced in two transplant programs in 2016 to evaluate its effectiveness.ObjectiveThis study assessed barriers and facilitators to HKTP implementation preparation.MethodsInterviews and group discussions were conducted with transplant stakeholders (ie administrators, nurses, physicians) during implementation preparation. The Consolidated Framework for Implementation Research (CFIR) guided interview design and qualitative analysis.ResultsForty-four stakeholders participated in 24 interviews and/or 27 group discussions. New factors, not found in previous implementation preparation research in health-care settings, emerged as facilitators and barriers to the implementation of culturally competent care. Implementation facilitators included: stakeholders' focus on a moral imperative to implement the HKTP, personal motivations related to their Hispanic heritage, and perceptions of Hispanic patients' transplant education needs. Implementation barriers included: stakeholders' perceptions that Hispanics' health insurance payer mix would negatively impact revenue, a lack of knowledge about LDKT disparities and patient data disaggregated by ethnicity/race, and a perception that the family discussion component was immoral because of the possibility of coercion.Discussion and conclusionsOur study identified novel barriers and facilitators to the implementation preparation of a culturally competent care intervention. Healthcare administrators can facilitate organizations' implementation of culturally competent care interventions by understanding factors challenging care delivery processes and raising clinical team awareness of disparities in LDKT.

Project description:ObjectiveTo determine if SARS-CoV-2, which has led to the rapidly spreading COVID-19 global pandemic, is sexually transmitted. Since the putative receptor for the virus is identified in reproductive organs, it is also important to examine if COVID-19 may affect human fertility.Evidence reviewA systematic review of English publications was conducted up to December 11, 2020 in PubMed, NIH iCite COVID-19 portfolio, Cochrane Library, and Google Scholar databases, searching for SARS-CoV-2 in the testes; seminal, prostatic, and vaginal fluids; and cervical smears. A total of 1,997 records were identified, duplicates were removed, and 1,490 records were reviewed for eligibility by examining titles and abstracts. Subsequently, 202 full-text relevant articles were reviewed by 2 independent reviewers. Forty-seven studies (literature reviews, editorials, and guidelines) were assessed qualitatively, and 23 studies that tested the male and female reproductive tracts of patients with COVID-19 for SARS-CoV-2 were quantitatively analyzed.ResultsNo epidemiological investigations to date have described evidence suggesting that COVID-19 is an STD. While angiotensin-converting enzyme 2 receptor is found in the reproductive organs, the lack of co-expression of the TMPRSS2 modulatory protein, required for SARS-CoV-2 cell entry, in testicular cells, sperm, or oocytes, argues against the hypothesis that gametes transmit SARS-CoV-2. Molecular detection studies of SARS-CoV-2 RNA in the male and female reproductive tracts were summarized: 98.0% (293/299) of the seminal fluids, 16/17 testicular biopsies, all 89 prostatic fluids, 98.3% (57/58) of the vaginal fluids, all 35 cervical smears, and all 16 oocyte samples tested negative for SARS-CoV-2. None of the studies confirmed sexual transmission of SARS-CoV-2. Nonetheless, COVID-19 may have detrimental effects on male reproduction by inducing orchitis and/or decreasing testosterone levels, sperm counts, and motility.ConclusionOn the basis of the current worldwide published information, COVID-19 is not an STD. This information is important for clinicians, proposed guidelines for public health, U.S. Food and Drug Administration guidelines for gamete and tissue donor eligibility, and fertility treatments. Universal precautions, currently practiced worldwide, are adequate and sufficient at this time to prevent the transmission of known or unknown viral infections. We suggest that recovered patients of COVID-19, especially those with infertility, should be evaluated for their ovarian and testicular function.

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Evolutionary dynamics of culturally transmitted, fertility-reducing traits.

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