Family ties and firm performance: How cousin marriage traditions shape informal businesses in Africa

Strategic Management Society

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A new study published in the Strategic Entrepreneurship Journal examines how long-standing cultural practices, specifically cousin marriage traditions, continue to influence business outcomes in sub-Saharan Africa's informal economy.

Researchers Saul Estrin (London School of Economics), Tomasz Mickiewicz (Aston University), and Peng Zhang (University of Sheffield) analyzed survey data from over 3,000 informal entrepreneurs across eight African countries. They explored how pre-colonial family structures—especially the practice of marrying within the extended family—affect key indicators of business performance, such as employment and revenue.

Cousin marriage, defined in the study as the practice of marrying within a kinship group, has deep historical roots in many African ethnic communities. The tradition reinforces in-group identity and tightly knit social networks, which in turn influence how small businesses make decisions about hiring and growth.

The researchers found that firms operating in areas with a historical tradition of cousin marriage were more likely to use additional financial resources to hire relatives or in-group members, leading to greater employment increases but smaller gains in revenue. In contrast, firms in communities without such traditions tended to prioritize revenue growth and acted more individualistically in their business decisions.

“These findings suggest that family systems and social expectations play a significant role in shaping how informal entrepreneurs allocate resources,” said Zhang. “Even when cousin marriage is no longer widely practiced, its underlying norms—like the emphasis on supporting the in-group—can persist and continue to influence behavior.”

The study also explores how colonization altered these long-standing family norms. The authors found that British colonial rule, with its emphasis on individualistic legal and administrative structures, was associated with a weakening of the cousin marriage tradition in many areas. These changes, however, varied by region and were influenced by competing cultural forces, including Islamic and Christian missionary activity.

The persistence of cultural norms over generations—even after formal practices change—highlights the importance of understanding historical context in business environments. Informal firms, which make up a large share of the African economy, often operate without formal regulation and rely heavily on community and family structures for support.

The authors emphasize that the implications extend beyond the informal sector. Multinational companies and policy makers working in sub-Saharan Africa should recognize that social institutions like cousin marriage traditions may influence the behavior and goals of local business partners and subcontractors.

To read the full context of the study and its methods, access the full paper available in the Strategic Entrepreneurship Journal.

About the Strategic Management Society

The Strategic Management Society (SMS) is the leading global member organization fostering and supporting rigorous and practice-engaged strategic management research. SMS enjoys the support of 3,000 members, representing more than 1,100 institutions and companies in more than 70 countries. SMS publishes three leading academic journals in partnership with Wiley: Strategic Management Journal, Strategic Entrepreneurship Journal, and Global Strategy Journal. These journals publish top-quality work applicable to researchers and practitioners with complementary access for all SMS Members. The SMS Explorer offers the latest insights and takeaways from the SMS Journals for business practitioners, consultants, and academics.

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Journal

Strategic Entrepreneurship Journal

DOI

10.1002/sej.1549 

Method of Research

Data/statistical analysis

Article Title

The cousin marriage tradition, colonial shocks, and the performance of informal firms in sub-Saharan Africa

Article Publication Date

1-Jun-2025

 

Novel flu vaccine adjuvant improves protection against influenza viruses, study finds

Georgia State University

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ATLANTA — Influenza hemagglutinin subunit vaccines are more effective and offer better cross protection against various influenza virus challenges when combined with a mucosal adjuvant that enhances the body’s immune response, according to a study by researchers in the Institute for Biomedical Sciences at Georgia State University.

The study published in the journal ACS Nano shows that immune cell-derived extracellular vesicles, specifically those from mature bone marrow-derived dendritic cells (which are crucial for immune responses), rather than those from immature dendritic cells, are potent mucosal adjuvants for influenza hemagglutinin vaccines.

The influenza hemagglutinin subunit vaccine is a type of influenza vaccine that primarily contains the surface protein hemagglutinin of the influenza virus. Mucosal adjuvants are substances that can enhance the body’s immune response to foreign materials in the mucosa, such as the surface of the respiratory tract, study authors explained.

Existing seasonal influenza vaccines have limited effectiveness against evolved virus strains, so next-generation, cross-protective influenza vaccines are urgently needed. Recombinant protein subunit vaccines have gained attention in vaccine development due to their safety, ease of large-scale manufacturing and affordability. Protein subunit vaccines can be designed to target specific pathogen components, leading to more focused immune responses.

Studies have found that mucosal immunization is a promising strategy against respiratory infectious diseases because it helps prevent the infection and transmission of respiratory pathogens and exhibits potential cross protection. However, the effectiveness of protein vaccines administered mucosally is limited, so there’s a need for safe and effective mucosal adjuvants. This study investigated the potential of extracellular vesicles derived from mature dendritic cells as mucosal adjuvants for influenza hemagglutinin vaccines.

Prior to this study, the mucosal adjuvant potential of extracellular vesicles derived from mature dendritic cells and the underlying mechanisms of action have been unknown.

“Immune cell-derived extracellular vesicles, which play crucial roles in intercellular communication and modulating biological responses, are potent mucosal adjuvants for influenza hemagglutinin vaccines,” said Bao-Zhong Wang, senior author of the study and a Distinguished University Professor in the Institute for Biomedical Sciences at Georgia State.

“These vesicles exhibit intriguing immunostimulatory activity both in vitro and in vivo,” Wang said. “Specifically, they effectively activated antigen-presenting cells, macrophages and B cells in vitro, and promoted enhanced recruitment of airway immune cells, early lymphocyte activation and robust germinal center formation in mice.”

The study found that intranasal immunization of mice with the influenza hemagglutinin vaccine plus the extracellular vesicle adjuvant from mature bone marrow-derived dendritic cells elicited significant, cross-reactive, and multifaceted humoral and cellular immune responses at both systemic and mucosal sites, conferring complete protection against homologous and heterologous influenza virus challenges.

The researchers pointed out that extracellular vesicles derived from mature dendritic cells have gained significant attention in immunotherapy and vaccine development because they have a variety of immunologically active molecules crucial for effective presentation of antigens (foreign substances that induces an immune response in the body), as well as cell adhesion and fusion.

“These findings underscore the potential of extracellular vesicles from mature bone marrow-derived dendritic cells as a promising adjuvant or immunomodulatory target for the development of mucosal vaccines,” said Chunhong Dong, first author of the study and a postdoctoral fellow in the Institute for Biomedical Sciences at Georgia State. “Given their biocompatibility and solid adjuvanticity, mature bone marrow-derived dendritic cells represent a promising adjuvant candidate for mucosal vaccine development.”

Additional authors of the study include Lai Wei, Wandi Zhu, Joo Kyung Kim, Ye Wang, Priscilla Omotara and Arini Arsana of the Institute for Biomedical Sciences at Georgia State.

The study is funded by the National Institutes of Health (NIH)/National Institute of Allergy and Infectious Diseases (NIAID).

To read the study, visit https://pubs.acs.org/doi/10.1021/acsnano.5c08831.

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Journal

ACS Nano

DOI

10.1021/acsnano.5c08831 

Method of Research

Experimental study

Subject of Research

Animals

Article Title

Mature Dendritic Cell-Derived Extracellular Vesicles are Potent Mucosal Adjuvants for Influenza Hemagglutinin Vaccines

Article Publication Date

1-Jul-2025

 

Experts say seafood deregulation could impact sustainability and supply

Peer-Reviewed Publication

University of California - Santa Barbara

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(Santa Barbara, Calif.) — A sweeping new executive order to deregulate the U.S. seafood sector risks unraveling decades of scientific progress and environmental protections, according to aquaculture and fishery scientists writing in a new paper published in the journal Marine Policy. Rather than strengthening the industry, they argue, the policy threatens the very systems that support sustainable seafood.  

“(It’s) a significant escalation in undoing federal regulatory frameworks, weakening scientific authority and deemphasizing aquaculture development,” state professors Halley Froehlich of UC Santa Barbara and Jessica Gephart at the University of Washington. “Instead of reform, it’s dismantling regulations in a very short amount of time,” added Froehlich, the paper’s lead author.  

Enacted in April 2025, “Restoring American Seafood Competitiveness,” states that “in addition to overregulation, unfair trade practices have put our seafood markets at a competitive disadvantage.” The executive order calls for actions to ensure the integrity of the seafood supply chain, eliminate unsafe imports and reduce regulatory burdens, among other things.

However, according to the researchers, the rush to fulfill the mandate, coupled with less funding and personnel to do so, presents more chaos than benefit, which could ultimately make the U.S. seafood sector less competitive. This can be seen in the weakening of the role of the National Oceanic and Atmospheric Administration (NOAA), the agency tasked with managing roughly 500 U.S. commercial fishery stocks. 

Deep cuts to the agency’s budget and workforce, as well as restrictions on communications are bound to make it more difficult to coordinate and plan the fishing of species, especially those that move and migrate across international borders.

“It’s quite problematic because NOAA is so central to how we manage our fisheries,” Froehlich said. “Data collection, monitoring, oversight, you name it, NOAA is part of that, and a really important part.”

While the move to deregulate is an attempt to increase the production and profitability of U.S. seafood, the end result is unlikely to be worth the effort, expense and weakening of environmental regulations, the authors argue, given that U.S. and global wild fisheries already produce near maximum levels. According to Froehlich and Gephart, aquaculture — farmed fish, shellfish and other marine and aquatic organisms — is the growth sector for both the economy and food security.

“We are not going to get more out of the ocean,” Froehlich said. “We’re already near ‘peak fish,’ meaning maintenance and recovery of our stocks.” In the researchers’ comparison between a 2020 executive order and this new one, aquaculture receives very little attention.  They argue that in a climate of funding cuts to federal agencies tasked with overseeing aquaculture, this oversight represents a mismatch between the intention of the executive order and the understanding, expertise and funding required to successfully increase the nation’s competitiveness in the seafood sector.

In addition, the potential decommissioning of numerous NOAA databases and online resources and the defunding of research, particularly in the realm of climate change, may be a detriment to efforts to expand seafood production, the researchers warn. Without the ability to monitor species and keep track of climate trends, the seafood sector also loses the ability to predict and respond quickly to emerging problems. “Without the data, expertise and capacity to study and understand these systems we run the risk of fishery collapses becoming more common and long-lasting,” they assert.

The researchers also point out inconsistencies related to seafood sourcing in the recent executive order, among them oversimplifications that do not account for market realities in the U.S. seafood sector. For one thing, the seafood that the U.S. tends to farm in volume are not the types of seafood that are of highest demand domestically, which could undermine efforts to substitute imports with domestic production. On top of that, potential tariffs levied on foreign seafood and U.S.-landed but foreign processed seafood could ultimately make seafood even more expensive for Americans, particularly high-demand species such as shrimp, of which only 10% of U.S. supply is locally produced.

“In disrupting the market dynamics we do have, especially with trade wars with our trading partners, it’s likely that we’re going to have the opposite effect of creating opportunity long-term,” said Froehlich. The paper was recently entered as evidence for a recent hearing of the House Natural Resources Committee’s Water, Wildlife and Fisheries Subcommittee, which is tasked with making Congressional decisions concerning fisheries management. “When it comes to any shifts in production, these high levels of uncertainty are not a beneficial thing to happen for the sector,” she said.

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Journal

Marine Policy

Article Title

Uncertain United States seafood sustainability in a manufactured crisis

 

Plants seek friendly environments rather than adapt

University of California - Davis

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image: 

A specimen of a jewelflower (Streptanthus brewerii) from the John M. Tucker Herbarium at UC Davis. Species of jewelflowers are found in areas of California that are generally cooler and wetter than the southwest deserts where the group originated. But a new study based on herbarium collections shows that jewelflowers select specific areas and flowering times that allow them to live in a warmer, drier climate than their overall surroundings.

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Credit: UC Davis

As jewelflowers spread into California from the desert Southwest over the past couple of million years, they settled in places that felt like home, according to a new study from the University of California, Davis. The work, published July 1 in Proceedings of the National Academy of Sciences, shows that the ability of plants and animals to adapt to changing climates might be more limited than it appears.

“I was honestly surprised,” said Sharon Strauss, Distinguished Professor emeritus in the Department of Evolution and Ecology and corresponding author on the paper. “They haven’t evolved as much as you would think.”

The study also shows the important role that herbaria — collections of pressed and dried plants — can play in ecological research.

Jewelflowers (Streptanthus) began to spread into California two to four million years ago as the climate became “Mediterranean” with a rainy season from fall to spring and a hot, dry summer. Jewelflower species are now found across the region, in areas that are much colder and wetter overall than the deserts where they originated.

Strauss, postdoctoral scholar Megan Bontrager and colleagues used about 2,000 specimens of 14 species of jewelflowers from the Consortium of California Herbaria, an online resource that draws on multiple plant collections, including UC Davis’ own herbarium.

The collections include records of when and where the specimen was collected and often other data as well.

Most jewelflowers are annual plants that germinate with the first significant rainfall of the season. By reconstructing local climate conditions for each specimen, the researchers could therefore estimate when the plant germinated from seed, and how long it had been growing before being collected. For example, a plant collected in June 1935 might have germinated in October 1934.

“We know how far they progressed on their one shot at life,” Strauss said.

Tracking the lived environment

Based on the average climate over a year, some jewelflower species live in areas much colder and wetter than others. But when the team looked at the local climate at the time the plants were growing above ground, a different picture emerged. The environments in which the growing plants spent their time were generally warmer and drier than surroundings. 

“If you look at the annual climate, you would think that they have diverged a lot, but actually the species are good at tracking hotter, drier times and areas,” Strauss said. For example, the plants might favor sunnier, south-facing slopes. At the northern end of their range, jewelflowers are found in areas with drier soils.

The research shows how the “lived” climate can be different from the annual climate when plants take advantage of microclimates or refuges, or use strategies such as changing their timing of germination or flowering.

It also shows how much herbarium specimens can contribute to ecological research.

“The beauty of herbarium specimens is that we have hundreds of years of collections under a wide range of conditions,” Strauss said.

Additional authors on the paper are: from UC Davis, Samantha Worthy, Laura Leventhal, Julin Maloof, Jennifer Gremer and Johanna Schmitt; and N. Ivalú Cacho, Universidad Nacional Autónoma de México. Megan Bontrager is now an assistant professor at the University of Toronto.

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Journal

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.250367012 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Herbarium specimens reveal a constrained seasonal climate niche despite diverged annual climates across a wildflower clade

Article Publication Date

1-Jul-2025

 

Black emergency department patients less likely to be treated with opioids – and more likely to misuse them later as a result

University of California - Los Angeles Health Sciences

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A new study examining racial disparities in unmet pain treatment finds that patients suffering from acute pain whose opioid treatment preferences were not met during an emergency department visit are at elevated risk for misusing them three months later. This was particularly true for Black patients, who were likelier than whites to be sent home without an opioid prescription. Patients who were satisfied with how their pain was managed in the emergency department were, however, less likely to misuse opioids, even if their preference for opioids was not honored.

Why it matters

The findings shed light on how disparities in pain treatment can increase the risk of future opioid misuse, especially for Black patients. The findings challenge the consensus view that lower opioid prescribing is always safer, highlighting the importance of patient experience and fairness in treatment. The study shines a light on a possibly overlooked cause for the disproportionate overdose deaths in Black communities: untreated pain and unmet expectations in the healthcare system.

The study

The researchers analyzed data on 735 participants collected from a randomized controlled trial conducted at six emergency departments at four academic medical centers. The primary outcome was opioid misuse risk as quantified by the Current Opioid Misuse Measure, or COMM, a 17-item, self-report measure of potential risk of misuse among people prescribed opioids for chronic pain that was taken 90 days after the patients’ emergency department visit.

What they found

Unmet preference for opioid treatment was more common among Black participants (21.8%) compared to white participants (15%). At low satisfaction (0/10), Black participants with unmet preferences had COMM scores nearly twice as high as their white counterparts; by high satisfaction (10/10), this gap disappeared. In contrast, among control participants, the Black/white difference in COMM scores was small and relatively stable across all satisfaction levels.

What's next

The next step is to examine why some patients feel less satisfied with their pain care than do others. Future research will explore factors shaping patients' satisfaction with pain care and their impact on opioid misuse risk, such as shared decision-making and patient-provider trust. 

From the experts

“While a great deal of studies on opioid misuse focus on overprescribing, this study flips the script by showing that under-prescribing—or more precisely, ignoring a patient’s pain treatment preferences—can also lead to harmful outcomes, especially when patients are dissatisfied with their care,” said Dr. Max Jordan Nguemeni, assistant professor-in-residence and the study’s lead author. “It’s one of the first to link racial disparities in pain treatment, patient satisfaction, and risk of opioid misuse in a single framework using longitudinal data.”

About the study

Racial Disparities in Unmet Pain Treatment Preference, Pain Treatment Satisfaction and Subsequent Opioid Misuse: A Secondary Analysis of a National Multisite RCT. Published online June 25, 2025 by the Journal of General Internal Medicine. DOI: 10.1007/s11606-025-09637-w.

About the Research Team

Study co-authors are Dr. Eden Engel-Rebitzer of Brigham & Women’s Hospital; Dr. Ari Friedman, Frances Shofer, Abby Dolan, Dr. Jeanmarie Perrone, Dr. Marilyn Schapira, and Dr. Zachary Meisel of the University of Pennsylvania, and Dr. Erik Hess of Vanderbilt University.

Funding and Disclosures

The Patient Centered Outcomes Research Institute (ID # CDR-1511–33496) funded the study.

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Journal

Journal of General Internal Medicine

DOI

10.1007/s11606-025-09637-w 

Method of Research

Randomized controlled/clinical trial

Subject of Research

People

Article Title

Racial Disparities in Unmet Pain Treatment Preference, Pain Treatment Satisfaction and Subsequent Opioid Misuse: A Secondary Analysis of a National Multisite RCT

 

Microplastics discovered in human reproductive fluids, new study reveals

New research reveals the presence of microplastics in human reproductive fluids, raising important questions about their potential risks to fertility and reproductive health

European Society of Human Reproduction and Embryology

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(Paris, France, Wednesday, 2 July 2025) New research presented today at the 41st Annual Meeting of the European Society of Human Reproduction and Embryology (ESHRE) reveals the presence of microplastics in human reproductive fluids, raising important questions about their potential risks to fertility and reproductive health.[1]

Researchers examined follicular fluid from 29 women and seminal fluid from 22 men, both of which play critical roles in natural conception and assisted reproduction.

A range of commonly used microplastic polymers, including polytetrafluoroethylene (PTFE), polystyrene (PS), polyethylene terephthalate (PET), polyamide (PA), polypropylene (PP) and polyurethane (PU), were identified in both groups.

Microplastics were present in 69% of the follicular fluid samples analysed. Notably, the most frequently detected polymer was PTFE, found in 31% of the samples. This was followed by PP (28%), PET (17%), PA (14%), polyethylene (PE) (10%), PU (10%) and PS (7%), in descending order of prevalence.

In male seminal fluid samples, microplastics were found in 55% of those analysed. PTFE again emerged as the most prevalent polymer, identified in 41% of the samples. Other polymers detected included PS (14%), PET (9%), PA (5%), and PU (5%), though in lower concentrations.

To prevent contamination, all samples were collected and stored in glass containers and underwent chemical treatment before analysis using laser direct infrared microscopy.

Lead researcher Dr. Emilio Gomez-Sanchez commented, “Previous studies had already shown that microplastics can be found in various human organs. As a result, we weren´t entirely surprised to find microplastics in fluids of the human reproductive system, but we were struck by how common they were – found in 69% of the women and 55% of the men we studied.”

Microplastics are defined as plastic particles under 5mm in size, and there is evidence that they pose a threat to environmental and public health.[2] While this research did not directly assess how microplastics affect fertility, their detection highlights the need to explore possible implications for human reproductive health.

“What we know from animal studies is that in the tissues where microplastics accumulate, they can induce inflammation, free radical formation, DNA damage, cellular senescence, and endocrine disruptions”, continued Dr. Gomez-Sanchez. “It’s possible they could impair egg or sperm quality in humans, but we don’t yet have enough evidence to confirm that.”

The research team plans to expand their analysis to a larger cohort, alongside detailed lifestyle and environmental exposure questionnaires. Further phases of the project will also explore the potential relationship between the presence of microplastics and oocyte and sperm quality.

Dr. Gomez-Sanchez stressed that fertility is influenced by many factors, including age, health, and genetics, and that the findings should not cause alarm among those trying to conceive. “There’s no need for alarm at this point. Microplastics are just one of many elements that may play a role in fertility. However, it is sensible to consider ways of reducing our exposure to them. Simple steps, such as using glass containers to store and heat food, or limiting the amount of water we consume from plastic bottles, can help minimise our intake.”

Professor Dr. Carlos Calhaz-Jorge, Immediate Past Chair of ESHRE, commented, “Environmental factors influencing reproduction are certainly a reality, although not easy to measure objectively. The authors of this study found microplastics in over two-thirds of follicular fluids and more than 50% of semen fluids from the studied patients. Although the significance of these findings is not yet clear, they should be considered an additional argument in favour of avoiding the generalised use of plastics in our daily lives.”

The study abstract will be published today in Human Reproduction, one of the world’s leading reproductive medicine journals.

 

ENDS

 

Notes to editors:

A reference to the ESHRE Annual Meeting must be included in all coverage and/or articles associated with this study.

For more information or to arrange an expert interview, please contact the ESHRE Press Office at: press@eshre.eu

About the study author:

Dr. Emilio Gomez-Sanchez holds a degree in Biological Sciences from the University of Seville and PhD in Biology from the University of Valencia. He completed a postdoctoral fellowship at the Medical Research Council (MRC) in Edinburgh (UK), funded by the European Union’s Human Capital and Mobility Programme. Since 1996, he has served as the director of an in vitro fertilisation (IVF) laboratory. He holds certification as a Senior Embryologist from the European Society of Human Reproduction and Embryology (ESHRE), and is also accredited as a Specialist in Assisted Human Reproduction by the Spanish Association for the Study of Reproductive Biology (ASEBIR). He has participated in numerous research projects funded by institutions such as CICYT, the Seneca Foundation, the Interministerial Commission for Science and Technology, the CDTi Research Programme, and the Instituto de Fomento de la Región de Murcia (INFO). He is the author of several publications in scientific journals and has been a speaker at various specialised conferences. Since 2006, he has been an Associate Professor at the University of Murcia. He is currently the director of the assisted reproduction laboratory at Next Fertility Murcia and serves as head embryologist and scientific coordinator at Gametia Gamete Bank.

https://www.linkedin.com/in/emiliogomezsanchez/?locale=en_US

About the European Society of Human Reproduction and Embryology

The main aim of ESHRE is to promote interest in infertility care and to aim for a holistic understanding of reproductive biology and medicine.

ESHRE collaborates world-wide and advocates universal improvements in scientific research, encourages and evaluates new developments in the field, and fosters harmonisation in clinical practice. It also provides guidance to enhance effectiveness, safety and quality assurance in clinical and laboratory procedures, psychosocial care, and promotes ethical practice. ESHRE also fosters prevention of infertility and related educational programmes and promotes reproductive rights regardless of the individual’s background. ESHRE’s activities include teaching, training, professional accreditations, mentoring and career planning for junior professionals, as well as developing and maintaining data registries. It also facilitates and disseminates research in human reproduction and embryology to the general public, scientists, clinicians, allied personnel, and patient associations.

Website: https://www.eshre.eu/

About Human Reproduction

Human Reproduction is a monthly journal of ESHRE and is one of the top three journals in the world in the field of reproductive biology, obstetrics and gynaecology. It is published by Oxford Journals, a division of Oxford University Press.

References:

[1] Gomez-Sanchez, E., et al. (2025) Unveiling the Hidden Danger: Detection and characterisation of microplastics in human follicular and seminal fluids. Human Reproduction. [insert link when available]

[2] Wang, L., Yin, Y., & He, X. (2024). The hidden threat: Unraveling the impact of microplastics on reproductive health. Science of the Total Environment, 912, 173177.