Paleolakes and socioecological implications of last glacial "greening" of the South African interior.

Determining the timing and drivers of Pleistocene hydrological change in the interior of South Africa is critical for testing hypotheses regarding the presence, dynamics, and resilience of human populations. Combining geological data and physically based distributed hydrological modeling, we demonstrate the presence of large paleolakes in South Africa's central interior during the last glacial period, and infer a regional-scale invigoration of hydrological networks, particularly during marine isotope stages 3 and 2, most notably 55 to 39 ka and 34 to 31 ka. The resulting hydrological reconstructions further permit investigation of regional floral and fauna responses using a modern analog approach. These suggest that the climate change required to sustain these water bodies would have replaced xeric shrubland with more productive, eutrophic grassland or higher grass-cover vegetation, capable of supporting a substantial increase in ungulate diversity and biomass. The existence of such resource-rich landscapes for protracted phases within the last glacial period likely exerted a recurrent draw on human societies, evidenced by extensive pan-side artifact assemblages. Thus, rather than representing a perennially uninhabited hinterland, the central interior's underrepresentation in late Pleistocene archeological narratives likely reflects taphonomic biases stemming from a dearth of rockshelters and regional geomorphic controls. These findings suggest that South Africa's central interior experienced greater climatic, ecological, and cultural dynamism than previously appreciated and potential to host human populations whose archaeological signatures deserve systematic investigation.

The meso-octoploid Heliophila variabilis genome sheds a new light on the impact of polyploidization and diploidization on the diversity of the Cape flora.

Although the South African Cape flora is one of the most remarkable biodiversity hotspots, its high diversity has not been associated with polyploidy. Here, we report the chromosome-scale genome assembly of an ephemeral cruciferous species Heliophila variabilis (~334 Mb, n = 11) adapted to South African semiarid biomes. Two pairs of differently fractionated subgenomes suggest an allo-octoploid origin of the genome at least 12 million years ago. The ancestral octoploid Heliophila genome (2n = 8x = ~60) has probably originated through hybridization between two allotetraploids (2n = 4x = ~30) formed by distant, intertribal, hybridization. Rediploidization of the ancestral genome was marked by extensive reorganization of parental subgenomes, genome downsizing, and speciation events in the genus Heliophila. We found evidence for loss-of-function changes in genes associated with leaf development and early flowering, and over-retention and sub/neofunctionalization of genes involved in pathogen response and chemical defense. The genomic resources of H. variabilis will help elucidate the role of polyploidization and genome diploidization in plant adaptation to hot arid environments and origin of the Cape flora. The sequenced H. variabilis represents the first chromosome-scale genome assembly of a meso-octoploid representative of the mustard family.

Virologic Failure and Drug Resistance After Programmatic Switching to Dolutegravir-based First-line Antiretroviral Therapy in Malawi and Zambia.

BACKGROUND: People with human immunodeficiency virus (PWH) on first-line, nonnucleoside reverse-transcriptase inhibitor-based antiretroviral therapy (ART) were routinely switched to tenofovir-lamivudine-dolutegravir. We examined virologic outcomes and drug resistance in ART programs in Malawi, where switching was irrespective of viral load, and Zambia, where switching depended on a viral load <1000 copies/mL in the past year. METHODS: We compared the risk of viremia (≥400 copies/mL) at 1 and 2 years by viral load at switch and between countries using exact methods and logistic regression adjusted for age and sex. We performed HIV-1 pol Sanger sequencing on plasma samples with viral load ≥1000 copies/mL. RESULTS: A total of 2832 PWH were eligible (Malawi 1422, Zambia 1410); the median age was 37 years, and 2578 (91.0%) were women. At switch, 77 (5.4%) were viremic in Malawi and 42 (3.0%) in Zambia (P = .001). Viremia at switch was associated with viremia at 1 year (adjusted odds ratio (OR), 6.15; 95% confidence interval [CI], 3.13-11.4) and 2 years (7.0; 95% CI, 3.73-12.6). Viremia was less likely in Zambia than in Malawi at 1 year (OR, 0.55; 0.32-0.94) and 2 years (OR, 0.33; 0.18-0.57). Integrase sequencing was successful for 79 of 113 eligible samples. Drug resistance mutations were found in 5 PWH (Malawi 4, Zambia 1); 2 had major mutations (G118R, E138K, T66A and G118R, E138K) leading to high-level dolutegravir resistance. CONCLUSIONS: Restricting switching to dolutegravir-based ART to PWH with a viral load <1000 copies/mL may reduce subsequent viremia and, consequently, the emergence of dolutegravir drug resistance mutations. CLINICAL TRIALS REGISTRATION: Clinicaltrials.gov (NCT04612452).

Yeast-insect interactions in southern Africa: Tapping the diversity of yeasts for modern bioprocessing.

Yeast-insect interactions are one of the most interesting long-standing relationships whose research has contributed to our understanding of yeast biodiversity and their industrial applications. Although insect-derived yeast strains are exploited for industrial fermentations, only a limited number of such applications has been documented. The search for novel yeasts from insects is attractive to augment the currently domesticated and commercialized production strains. More specifically, there is potential in tapping the insects native to southern Africa. Southern Africa is home to a disproportionately high fraction of global biodiversity with a cluster of biomes and a broad climate range. This review presents arguments on the roles of the mutualistic relationship between yeasts and insects, the presence of diverse pristine environments and a long history of spontaneous food and beverage fermentations as the potential source of novelty. The review further discusses the recent advances in novelty of industrial strains of insect origin, as well as various ancient and modern-day industries that could be improved by use yeasts from insect origin. The major focus of the review is on the relationship between insects and yeasts in southern African ecosystems as a potential source of novel industrial yeast strains for modern bioprocesses.

Revisiting an ecophysiological oddity: Hydathode-mediated foliar water uptake in Crassula species from southern Africa.

Hydathodes are usually associated with water exudation in plants. However, foliar water uptake (FWU) through the hydathodes has long been suspected in the leaf-succulent genus Crassula (Crassulaceae), a highly diverse group in southern Africa, and, to our knowledge, no empirical observations exist in the literature that unequivocally link FWU to hydathodes in this genus. FWU is expected to be particularly beneficial on the arid western side of southern Africa, where up to 50% of Crassula species occur and where periodically high air humidity leads to fog and/or dew formation. To investigate if hydathode-mediated FWU is operational in different Crassula species, we used the apoplastic fluorescent tracer Lucifer Yellow in combination with different imaging techniques. Our images of dye-treated leaves confirm that hydathode-mediated FWU does indeed occur in Crassula and that it might be widespread across the genus. Hydathodes in Crassula serve as moisture-harvesting structures, besides their more common purpose of guttation, an adaptation that has likely played an important role in the evolutionary history of the genus. Our observations suggest that ability for FWU is independent of geographical distribution and not restricted to arid environments under fog influence, as FWU is also operational in Crassula species from the rather humid eastern side of southern Africa. Our observations point towards no apparent link between FWU ability and overall leaf surface wettability in Crassula. Instead, the hierarchically sculptured leaf surfaces of several Crassula species may facilitate FWU due to hydrophilic leaf surface microdomains, even in seemingly hydrophobic species. Overall, these results confirm the ecophysiological relevance of hydathode-mediated FWU in Crassula and reassert the importance of atmospheric humidity for some arid-adapted plant groups.

Acceptability of the Dapivirine Vaginal Ring and Daily Oral Pre-exposure Prophylaxis (PrEP) during Pregnancy in Malawi, South Africa, Uganda, and Zimbabwe.

Pregnant and lactating persons in sub-Saharan Africa face a heightened risk of HIV acquisition, due to biological and behavioral factors, combined with limited access to prevention and treatment services. Oral pre-exposure prophylaxis (PrEP) and the dapivirine vaginal ring are promising tools for HIV prevention, and the ring's recent approval in multiple African countries represents a significant advancement in expanding access to HIV prevention. In a nested qualitative study within the MTN-042 trial, we explored the acceptability of study products among pregnant persons in the second and early third trimesters. Interviews were conducted privately, using a semi-structured guide with 77 participants, in participants' preferred language. Topics explored included product acceptability (using the theoretical framework of acceptability), user experience, satisfaction, disclosure, community attitudes, and sexual activity during pregnancy. Interview transcripts were analyzed using Dedoose software. We observed positive attitudes among participants towards the study products, which they found generally user-friendly, despite the added complexities of using them during pregnancy. Participants recognized that consistent and correct use would provide protection for both them and their unborn children. Although initial concerns existed, most of these worries dissipated over time, with study staff support and increased product use experience. These findings emphasize the importance of continued surveillance, support, and education to ensure the successful rollout of new HIV prevention measures during pregnancy.

A plea for urgent action: Addressing the critical shortage of cardiothoracic surgical workforce in the COSECSA region.

BACKGROUND: The College of Surgeons of East, Central, and Southern Africa (COSECSA) comprises 14 countries, many of which currently grapple with an increasing burden of cardiothoracic surgical (CTS) diseases. Health and economic implications of unaddressed CTS conditions are profound and require a robust regional response. This study aimed to define the status of CTS specialist training in the region (including the density of specialists, facilities, and active training posts), examine implications, and proffer recommendations. METHODS: A desk review of COSECSA secretariat documents and program accreditation records triangulated with information from surgical societies was performed in May 2022 and September 2023 as part of education quality improvement. A modified nominal group process involving contextual experts was used to develop a relevant action framework. RESULTS: Only 6 of 14 (43%) of COSECSA countries offered active training programs with annual intake of only 18 trainees. Significant training gaps existed in Burundi, Botswana, Malawi, Rwanda, South Sudan, Zambia, and Zimbabwe. Country specialist density ranged from 1 per 400,000 (Namibia) to 1 per 8,000,000 (Ethiopia). Overall, the region had 0.2 CTS specialists per million population as compared with 7.15 surgeons per million in High-Income Countries. Surgical education experts proposed an action framework to address the training crisis including increasing investments in CTS education, establishing regional centers of excellence, retention incentives and opportunities for women, and leveraging international partnerships. CONCLUSION: Proactive investments in infrastructure, human resources, training, and collaborative efforts by national governments, regional intergovernmental organizations, and international partners are critical to expanding regional CTS training.

Perception of couples' on multipurpose prevention technology attribute choice: the case of MTN 045.

BACKGROUND: Multipurpose prevention technologies (MPTs) are products capable of simultaneously addressing multiple sexual and reproductive health needs such as unwanted pregnancy, STIs including HIV-1, and other reproductive tract infections. MPTs are urgently needed to address the double burden of unplanned pregnancy and HIV. While condoms are currently the only accessible MPTs, they are not solely under a woman's control, and female condoms face limitations due to poor acceptability and high cost. METHODS: We conducted a sub-analysis of qualitative data from 39 couples participating in the MTN 045 study to examine the perception of couples on choice and acceptability of a "2 in 1" MPT that combines HIV and pregnancy prevention. RESULTS: Couples recognized the benefits of MPTs for HIV and pregnancy prevention but perceptions tied to each indication and a novel prevention technology tool raised important concerns relevant to use of future MPTs. In the study, participants' perceptions of MPT use were influenced by pregnancy planning. When the timing was less critical, they prioritized HIV prevention. Misinformation about family planning methods, including MPTs, affected decision-making with potential to hinder uptake of future MPTs. Concerns about side effects, such as weight gain and hormonal imbalances, influenced willingness to use MPTs. CONCLUSION: Addressing the myths and misconceptions surrounding the use of contraceptives is crucial in promoting their acceptance and ultimate use. Strategies for addressing the drawbacks women might experience while using a particular product should be in place as new MPTs progress through the development pipeline and approach roll-out.

Early, intensive marine resource exploitation by Middle Stone Age humans at Ysterfontein 1 rockshelter, South Africa.

Modern human behavioral innovations from the Middle Stone Age (MSA) include the earliest indicators of full coastal adaptation evidenced by shell middens, yet many MSA middens remain poorly dated. We apply 230Th/U burial dating to ostrich eggshells (OES) from Ysterfontein 1 (YFT1, Western Cape, South Africa), a stratified MSA shell midden. 230Th/U burial ages of YFT1 OES are relatively precise (median ± 2.7%), consistent with other age constraints, and preserve stratigraphic principles. Bayesian age-depth modeling indicates YFT1 was deposited between 119.9 to 113.1 thousand years ago (ka) (95% CI of model ages), and the entire 3.8 m thick midden may have accumulated within ∼2,300 y. Stable carbon, nitrogen, and oxygen isotopes of OES indicate that during occupation the local environment was dominated by C3 vegetation and was initially significantly wetter than at present but became drier and cooler with time. Integrating archaeological evidence with OES 230Th/U ages and stable isotopes shows the following: 1) YFT1 is the oldest shell midden known, providing minimum constraints on full coastal adaptation by ∼120 ka; 2) despite rapid sea-level drop and other climatic changes during occupation, relative shellfish proportions and sizes remain similar, suggesting adaptive foraging along a changing coastline; 3) the YFT1 lithic technocomplex is similar to other west coast assemblages but distinct from potentially synchronous industries along the southern African coast, suggesting human populations were fragmented between seasonal rainfall zones; and 4) accumulation rates (up to 1.8 m/ka) are much higher than previously observed for dated, stratified MSA middens, implying more intense site occupation akin to Later Stone Age middens.

Healthy environments for athleTes (HEAT): environmental conditions along a 90 km ultra-marathon event, South Africa.

This paper provides an overview of the HEAT (Healthy Environments for AthleTes) project, which aims to understand the impact of environmental conditions on athlete health and performance during major sporting events such as long-distance running, cycling, and triathlons. In collaboration with the SAFER (Strategies to reduce Adverse medical events For the ExerciseR) initiative, the HEAT project carried out a field campaign at the 2022 Comrades Marathon in the KwaZulu-Natal province of South Africa. The measurement campaign deployed seven weather stations, seven PM2.5 monitors and one spore trap along the 90 km route to capture spatially representative measurements of complex micro-climates, allergenic aerospora, and particulate matter exposure. The results indicate that runners were exposed to moderate risk heat stress conditions. Novel findings from this initial campaign shows elevated and potentially harmful PM2.5 levels at spectator areas, possibly coinciding with small fire events around the race day festivities. Our findings show values PM2.5 levels over the WHO 24-h guidelines at all stations, while 2000 µg/m3 at two stations. However, the lack of an acute exposure standard means direct health impacts cannot be quantified in the context of a sport event. The HEAT project highlights important aspects of race day monitoring; regional scale climatology has an impact on the race day conditions, the microclimatic conditions (pollution and meteorology) are not necessarily captured by proximity instruments and direct environmental measurements are required to accurately capture conditions along the route.

Comment on 'Changing relationships between HIV prevalence and circumcision in Lesotho', and 'Age-incidence and prevalence of HIV among intact and circumcised men: an analysis of PHIA surveys in Southern Africa'.

Two articles by Garenne (2023a,b) argue that voluntary medical male circumcision does not reduce human immunodeficiency virus transmission in Africa. Here we point out key evidence and analytical flaws that call into question this conclusion.

Seroprofiling of Antibodies Against Endemic Human Coronaviruses and Severe Acute Respiratory Syndrome Coronavirus 2 in a Human Immunodeficiency Virus Cohort in Lesotho: Correlates of Antibody Response and Seropositivity.

BACKGROUND: Serological data on endemic human coronaviruses (HCoVs) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in southern Africa are scarce. Here, we report on (1) endemic HCoV seasonality, (2) SARS-CoV-2 seroprevalence, and (3) correlates of SARS-CoV-2 seropositivity and strength of SARS-CoV-2 and endemic HCoV serological responses among adults living with human immunodeficiency virus (HIV). METHODS: Plasma samples were collected from February 2020 to July 2021 within an HIV cohort in Lesotho. We used the AntiBody CORonavirus Assay (ABCORA) multiplex immunoassay to measure antibody responses to endemic HCoV (OC43, HKU1, NL63, and 229E) and SARS-CoV-2 antigens. RESULTS: Results for 3173 samples from 1403 adults were included. Serological responses against endemic HCoVs increased over time and peaked in winter and spring. SARS-CoV-2 seropositivity reached >35% among samples collected in early 2021 and was associated with female sex, obesity, working outside the home, and recent tiredness or fever. Positive correlations were observed between the strength of response to endemic HCoVs and to SARS-CoV-2 and between older age or obesity and the immunoglobulin G response to SARS-CoV-2. CONCLUSIONS: These results add to our understanding of the impact of biological, clinical, and social/behavioral factors on serological responses to coronaviruses in southern Africa.

T-SPOT.TB Reactivity in Southern African Children With and Without in Utero Human Immunodeficiency Virus Exposure.

Infants who are human immunodeficiency virus (HIV)-exposed uninfected (iHEU) experience higher risk of infectious morbidity than infants HIV-unexposed uninfected (iHUU). We compared tuberculosis (TB) infection prevalence in 418 Bacillus Calmette-Guérin vaccinated sub-Saharan African iHEU and iHUU aged 9-18 months using T-SPOT.TB. Prevalence of TB infection was low and did not differ by HIV exposure status.

Capacity to Consent to Research Among Adolescent-Parent Dyads in Rakai, Uganda.

OBJECTIVES: To assess the cognitive capacity of early, middle, and late adolescents and their parents or guardians to provide informed consent to a population-based cohort study. STUDY DESIGN: Adolescent-parent/guardian dyads including 40 early (n = 80; 10-14 years), 20 middle (15-17 years), and 20 late (18-19 years) adolescents were recruited from the Rakai Community Cohort Study, an open demographic cohort in Uganda. Participants were administered the MacArthur Competence Assessment Tool for Clinical Research, a structured open-ended assessment; interviews were recorded and transcribed. Twenty transcripts were scored independently by two coders; the intraclass correlation coefficient was 0.89. The remaining interviews were scored individually. We compared mean scores for early and middle/late adolescents using a one-sided t test and score differences between parent/guardian and adolescent dyads using two-sided paired t tests. RESULTS: Early adolescents (mean score, 28.8; 95% CI, 27.1-30.5) scored significantly lower (P < .01) than middle/late adolescents (32.4; 31.6-33.1). In paired dyad comparisons, we observed no statistically significant difference in scores between parents/guardians and middle/late adolescents (difference, -0.2; 95% CI, -1.0-0.6). We found a statistically significant difference in scores between parents/guardians and early adolescents (difference, 3.0; 95% CI, 1.2-4.8). CONCLUSIONS: The capacity of adolescents-of different ages and in diverse settings-to comprehend risks, benefits, and other elements of informed consent is a critical but understudied area in research ethics. Our findings support the practice of having middle and late adolescents provide independent informed consent for sexual and reproductive health studies. Early adolescents may benefit from supported decision-making approaches.

Phylogenomics sheds new light on the drivers behind a long-lasting systematic riddle: the figwort family Scrophulariaceae.

The figwort family, Scrophulariaceae, comprises c. 2000 species whose evolutionary relationships at the tribal level have proven difficult to resolve, hindering our ability to understand their origin and diversification. We designed a specific probe kit for Scrophulariaceae, targeting 849 nuclear loci and obtaining plastid regions as by-products. We sampled c. 87% of the genera described in the family and use the nuclear dataset to estimate evolutionary relationships, timing of diversification, and biogeographic patterns. Ten tribes, including two new tribes, Androyeae and Camptolomeae, are supported, and the phylogenetic positions of Androya, Camptoloma, and Phygelius are unveiled. Our study reveals a major diversification at c. 60 million yr ago in some Gondwanan landmasses, where two different lineages diversified, one of which gave rise to nearly 81% of extant species. A Southern African origin is estimated for most modern-day tribes, with two exceptions, the American Leucophylleae, and the mainly Australian Myoporeae. The rapid mid-Eocene diversification is aligned with geographic expansion within southern Africa in most tribes, followed by range expansion to tropical Africa and multiple dispersals out of Africa. Our robust phylogeny provides a framework for future studies aimed at understanding the role of macroevolutionary patterns and processes that generated Scrophulariaceae diversity.

Does Host Plant Drive Variation in Microbial Gut Communities in a Recently Shifted Pest?

Biotic interactions can modulate the responses of organisms to environmental stresses, including diet changes. Gut microbes have substantial effects on diverse ecological and evolutionary traits of their hosts, and microbial communities can be highly dynamic within and between individuals in space and time. Modulations of the gut microbiome composition and their potential role in the success of a species to maintain itself in a new environment have been poorly studied to date. Here we examine this question in a large wood-boring beetle Cacosceles newmannii (Cerambycidae), that was recently found thriving on a newly colonized host plant. Using 16S metabarcoding, we assessed the gut bacterial community composition of larvae collected in an infested field and in "common garden" conditions, fed under laboratory-controlled conditions on four either suspected or known hosts (sugarcane, tea tree, wattle, and eucalyptus). We analysed microbiome variation (i.e. diversity and differentiation), measured fitness-related larval growth, and studied host plant lignin and cellulose contents, since their degradation is especially challenging for wood-boring insects. We show that sugarcane seems to be a much more favourable host for larval growth. Bacterial diversity level was the highest in field-collected larvae, whereas lab-reared larvae fed on sugarcane showed a relatively low level of diversity but very specific bacterial variants. Bacterial communities were mainly dominated by Proteobacteria, but were significantly different between sugarcane-fed lab-reared larvae and any other hosts or field-collected larvae. We identified changes in the gut microbiome associated with different hosts over a short time frame, which support the hypothesis of a role of the microbiome in host switches.

Adolescent Girls and Young Women's Experiences with Disclosing Oral PrEP or Dapivirine Vaginal Ring Use: a Multi-Country Qualitative Analysis.

Effective use of oral pre-exposure prophylaxis (PrEP) has been low among adolescent girls and young women (AGYW) in Eastern and Southern Africa, partly due to stigma and opposition from key influencers. Understanding AGYW's experiences of disclosure of different PrEP modalities to key influencers may inform strategies to motivate uptake and adherence. We analyzed qualitative in-depth interviews and focus group discussions data from 119 participants in the MTN-034/REACH (Reversing the Epidemic in Africa with Choices in HIV Prevention) study of oral PrEP and the dapivirine vaginal ring (ring) to explore AGYW's disclosure experiences. We found that AGYW disclosure experiences varied across influencers and product type. The ring was disclosed less often to most influencers, except partners, because it was discreet. Oral PrEP was disclosed more often, because pills were more common and to avoid HIV stigma given that oral PrEP resembled HIV treatment. Ultimately, disclosure typically led most key influencers to support product use through reminders and encouragement. While disclosure yielded positive support from influencers, further community awareness of both PrEP products is essential to reduce potential opposition and perceived stigma.Clinical Trial Number: NCT03593655.

Systematic review of prevalence and risk factors of transfusion transmissible infections among blood donors, and blood safety improvements in Southern Africa.

Blood and blood products are listed as one of the essential medicines by the World Health Organization (WHO). In addition to inadequate supply, most sub-Saharan Africa (SSA) nations fail to meet their blood needs because many donated blood units are discarded because they are contaminated with transfusion-transmitted infections (TTIs). We sought to estimate the prevalence of TTIs, identify the risk factors for TTIs among blood donors, and identify the efforts and interventions that have been made to improve blood safety in Southern African nations, particularly the nations of the South African Development Community (SADC). We investigated the prevalence and risk factors for TTIs, blood safety interventions, and blood quality improvement in the SADC region from major PubMed/MEDLINE, Cochrane Library, and HINARI databases from 1 January 2011 to 31 April 2021. All investigations followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). In meta-analysis, we estimated the pooled TTIs prevalence and summarised the same using forest plots. A total of 180 articles published from the SSA region were identified covering our three targeted themes: TTI prevalence, risk factors for TTIs, and blood safety improvements. Of these 180 articles, only 27 (15%) focused on the SADC region. The overall pooled TTI prevalence estimate was 2.0% (95% CI: 1.0-3.0) and hepatitis B was the most prevalent TTI in the region (prevalence = 3.0; 95% CI: 2.0-5.0). The prevalence of HIV, HCV, and syphilis was 2.0% (95% CI: 1.0-4.0), 1.0% (95% CI: 0.0-2.0), and 2.0% (95% CI: 0.0-8.0), respectively. In general, replacement donors and first-time donors were more likely to be infected with TTIs than repeat donors. Twelve articles explored blood safety research in the region; however, they vary greatly highlighting the need for consistent and more comprehensive research. Few publications were identified that were from the SADC region, indicating lack of research or resources towards improving both quantity and quality of blood donation. TTI prevalence remains one of the highest in the world and blood safety recommendations vary across the region. More effort should be directed towards developing a cohesive regional blood transfusion policy and effective blood monitoring and evaluation strategies.

Ostrich eggshell bead strontium isotopes reveal persistent macroscale social networking across late Quaternary southern Africa.

Hunter-gatherer exchange networks dampen subsistence and reproductive risks by building relationships of mutual support outside local groups that are underwritten by symbolic gift exchange. Hxaro, the system of delayed reciprocity between Ju/'hoãn individuals in southern Africa's Kalahari Desert, is the best-known such example and the basis for most analogies and models of hunter-gatherer exchange in prehistory. However, its antiquity, drivers, and development remain unclear, as they do for long-distance exchanges among African foragers more broadly. Here we show through strontium isotope analyses of ostrich eggshell beads from highland Lesotho, and associated strontium isoscape development, that such practices stretch back into the late Middle Stone Age. We argue that these exchange items originated beyond the macroband from groups occupying the more water-stressed subcontinental interior. Tracking the emergence and persistence of macroscale, transbiome social networks helps illuminate the evolution of social strategies needed to thrive in stochastic environments, strategies that in our case study show persistence over more than 33,000 y.

'Guidance should have been there 15 years ago' research stakeholders' perspectives on ancillary care in the global south: a case study of Malawi.

BACKGROUND: Medical researchers in resource-constrained settings must make difficult moral decisions about the provision of ancillary care to participants where additional healthcare needs fall outside the scope of the research and are not provided for by the local healthcare system. We examined research stakeholder perceptions and experiences of ancillary care in biomedical research projects in Malawi. METHODS: We conducted 45 qualitative in-depth interviews with key research stakeholders: researchers, health officials, research ethics committee members, research participants and grants officers from international research funding organisations. Thematic analysis was used to analyse and interpret the findings. FINDINGS: All stakeholders perceived the provision of ancillary care to have potential health benefits to study participants in biomedical research. However, they also had concerns, particularly related to the absence of guidance to support it. Some suggested that consideration for ancillary care provision could be possible on a case-by-case basis but that most of the support from research projects should be directed towards strengthening the public health system, emphasising public good above individual or personal benefits. Some researchers and ethics committee members raised concerns about potential tensions in terms of funding, for example balancing study demands with addressing participants' additional health needs. CONCLUSION: Our findings highlight the complexities and gaps in the guidance around the provision of ancillary care in Malawi and other resource-constrained settings more generally. To promote the provision of ancillary care, we recommend that national and international guidelines for research ethics include specific recommendations for resource-constrained settings and specific types of research.