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Wiley KS, Gregg AM, Fox MM, Lagishetty V, Sandman CA, Jacobs JP, Glynn LM. Contact with caregivers is associated with composition of the infant gastrointestinal microbiome in the first 6 months of life. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 183:e24858. [PMID: 37804008 PMCID: PMC10922139 DOI: 10.1002/ajpa.24858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/18/2023] [Accepted: 09/24/2023] [Indexed: 10/08/2023]
Abstract
OBJECTIVES Little is known about how physical contact at birth and early caregiving environments influence the colonization of the infant gastrointestinal microbiome. We investigated how infant contact with caregivers at birth and within the first 2 weeks of life relates to the composition of the gastrointestinal microbiome in a sample of U.S. infants (n = 60). METHODS Skin-to-skin and physical contact with caregivers at birth and early caregiving environments were surveyed at 2 weeks postpartum. Stool samples were collected from infants at 2 weeks, 2, 6, and 12 months of age and underwent 16S rRNA sequencing as a proxy for the gastrointestinal microbiome. Associations between early caregiving environments and alpha and beta diversity, and differential abundance of bacteria at the genus level were assessed using PERMANOVA, and negative binomial mixed models in DEseq2. RESULTS Time in physical contact with caregivers explained 10% of variation in beta diversity at 2 weeks' age. The number of caregivers in the first few weeks of life explained 9% of variation in beta diversity at 2 weeks and the number of individuals in physical contact at birth explained 11% of variation in beta diversity at 6 months. Skin-to-skin contact on the day of birth was positively associated with the abundance of eight genera. Infants held for by more individuals had greater abundance of eight genera. DISCUSSION Results reveal a potential mechanism (skin-to-skin and physical contact) by which caregivers influence the infant gastrointestinal microbiome. Our findings contribute to work exploring the social transmission of microbes.
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Affiliation(s)
- Kyle S Wiley
- Department of Anthropology, UCLA, Los Angeles, California, USA
- Department of Psychiatry & Biobehavioral Sciences, UCLA, Los Angeles, California, USA
| | - Andrew M Gregg
- The Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Molly M Fox
- Department of Anthropology, UCLA, Los Angeles, California, USA
- Department of Psychiatry & Biobehavioral Sciences, UCLA, Los Angeles, California, USA
| | - Venu Lagishetty
- The Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
- UCLA Microbiome Center, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
- Division of Gastroenterology, Hepatology and Parenteral Nutrition, VA Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Curt A Sandman
- Department of Psychiatry and Human Behavior, UC Irvine, Irvine, California, USA
| | - Jonathan P Jacobs
- The Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
- UCLA Microbiome Center, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
- Division of Gastroenterology, Hepatology and Parenteral Nutrition, VA Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Laura M Glynn
- Department of Psychology, Chapman University, Orange, California, USA
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Starkweather KE, Reynolds AZ, Zohora F, Alam N. Shodagor women cooperate across domains of work and childcare to solve an adaptive problem. Philos Trans R Soc Lond B Biol Sci 2023; 378:20210433. [PMID: 36440563 PMCID: PMC9703234 DOI: 10.1098/rstb.2021.0433] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 05/03/2022] [Indexed: 11/29/2022] Open
Abstract
Across human societies, women's economic production and their contributions to childcare are critical in supporting reproductive fitness for themselves, their spouses and children. Yet, the necessity of performing both work and childcare tasks presents women with an adaptive problem in which they must determine how best to allocate their time and energy between these tasks. Women often use cooperative relationships with alloparents to solve this problem, but whether or not women cooperate across different domains (e.g. work and childcare) to access alloparents remains relatively under-explored. Using social network data collected with Shodagor households in Bangladesh, we show that women who need childcare help in order to work draw on cooperative work partners as potential alloparents, and that all women rely heavily on kin, but not reciprocal cooperation for childcare help. These results indicate that Shodagor women strategize to create work and childcare relationships in ways that help solve the adaptive problem they face. We discuss the implications of our results and the example provided by Shodagor women for a broader understanding of women's cooperative relationships, including the importance of socio-ecological circumstances and gendered divisions of labour in shaping women's cooperative strategies. This article is part of the theme issue 'Cooperation among women: evolutionary and cross-cultural perspectives'.
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Affiliation(s)
- K. E. Starkweather
- Department of Anthropology, University of Illinois Chicago, Chicago, IL 60607, USA
- Department of Human Behavior, Ecology, and Culture, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany
| | - A. Z. Reynolds
- Department of Anthropology, University of New Mexico, Albuquerque, NM 8731, USA
| | - F. Zohora
- Health Systems and Population Studies Division, ICDDR,B, Dhaka 1212, Bangladesh
| | - N. Alam
- Health Systems and Population Studies Division, ICDDR,B, Dhaka 1212, Bangladesh
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Fox M, Wiley KS. How a pregnant woman's relationships with her siblings relate to her mental health: a prenatal allocare perspective. Evol Med Public Health 2021; 10:1-20. [PMID: 35154777 PMCID: PMC8830312 DOI: 10.1093/emph/eoab044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 12/07/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND In cooperatively breeding species, individuals may promote their inclusive fitness through allomothering. Humans exhibit some features of cooperative breeding, and previous studies have focused on allomothering by grandparents and juvenile siblings in the postnatal period. We hypothesize that a pregnant woman's relationships with her siblings (offspring's maternal aunts and uncles) are beneficial for maternal affect in ways that can enhance the siblings' inclusive fitness. Maternal affect during pregnancy is a salient target of allocare given the detrimental effects of antepartum mood disorders on birth and infant outcomes. METHODOLOGY We test our hypotheses in a cohort of pregnant Latina women in Southern California (N = 201). Predictor variables of interest include number of siblings a participant has, if she has sisters, frequency of seeing siblings, and frequency of communication with siblings. Outcome variables measuring maternal affect include depression, state anxiety, pregnancy-related anxiety and perceived stress. RESULTS Having at least one sister and greater frequency of communication with siblings were associated with fewer depressive symptoms during pregnancy. No significant associations were found between sibling variables and other measures of affect. CONCLUSION AND IMPLICATIONS Results suggest that how frequently you communicate with, and not how often you see, siblings could be protective against risk of antepartum depression. Sibling allomothering could impart effects through social-emotional support rather than instrumental support, as a strategy to benefit the prenatal environment in which future nieces and nephews develop. Allomothering may be particularly important in cultural contexts that value family relationships. Future studies should investigate other communities.
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Affiliation(s)
- Molly Fox
- Department of Anthropology, University of California Los Angeles, Los Angeles, CA, USA,Department of Psychiatry and Biobehavioral Sciences, University of California Los Angeles, Los Angeles, CA, USA,Corresponding author. Department of Anthropology, University of California Los Angeles, 341 Haines Hall, 375 Portola Plaza, Los Angeles, CA, USA. Tel: +1 (310) 206-4589; E-mail:
| | - Kyle S Wiley
- Department of Anthropology, University of California Los Angeles, Los Angeles, CA, USA,Department of Psychiatry and Biobehavioral Sciences, University of California Los Angeles, Los Angeles, CA, USA
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Helfrecht C, Roulette JW, Lane A, Sintayehu B, Meehan CL. Life history and socioecology of infancy. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 173:619-629. [PMID: 32955732 DOI: 10.1002/ajpa.24145] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 08/06/2020] [Accepted: 08/18/2020] [Indexed: 11/08/2022]
Abstract
OBJECTIVES Evolution of human maternal investment strategies is hypothesized to be tied to biological constraints and environmental cues. It is likely, however, that the socioecological context in which mothers' decisions are made is equally important. Yet, a lack of studies examining maternal investment from a cross-cultural, holistic approach has hindered our ability to investigate the evolution of maternal investment strategies. Here, we take a systems-level approach to study how human life history characteristics, environments, and socioecology influence maternal investment in their children. MATERIALS AND METHODS We test how infant age and sex, maternal age, parity, and child loss, and the composition of a child's cooperative breeding network are associated with maternal investment across three small-scale (hunter-gatherer, horticultural, and agropastoral), sub-Saharan populations (N = 212). Naturalistic behavioral observations also enable us to illustrate the breadth and depth of the human cooperative breeding system. RESULTS Results indicate that infant age, maternal age and parity, and an infant's cooperative childcare network are significantly associated with maternal investment, controlling for population. We also find that human allomaternal care is conducted by a range of caregivers, occupying different relational, sex, and age categories. Moreover, investment by allomothers is widely distributed. DISCUSSION Our findings illustrate the social context in which children are reared in contemporary small-scale populations, and in which they were likely reared throughout our evolutionary history. The diversity of the caregiving network, coupled with life history characteristics, is predictive of maternal investment strategies, demonstrating the importance of cooperation in the evolution of human ontogeny.
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Affiliation(s)
- Courtney Helfrecht
- Department of Anthropology, University of Alabama, Tuscaloosa, Alabama, USA
| | - Jennifer W Roulette
- Department of Anthropology, San Diego State University, San Diego, California, USA
| | - Avery Lane
- Department of Anthropology, Washington State University, Pullman, Washington, USA
| | - Birhanu Sintayehu
- Department of Educational Planning and Management, College of Education and Behavioral Sciences, Haramaya University, Dire Dawa, Ethiopia
| | - Courtney L Meehan
- Department of Anthropology, Washington State University, Pullman, Washington, USA
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Kramer KL, Veile A, Otárola-Castillo E. Sibling Competition & Growth Tradeoffs. Biological vs. Statistical Significance. PLoS One 2016; 11:e0150126. [PMID: 26938742 PMCID: PMC4777386 DOI: 10.1371/journal.pone.0150126] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 02/09/2016] [Indexed: 11/18/2022] Open
Abstract
Early childhood growth has many downstream effects on future health and reproduction and is an important measure of offspring quality. While a tradeoff between family size and child growth outcomes is theoretically predicted in high-fertility societies, empirical evidence is mixed. This is often attributed to phenotypic variation in parental condition. However, inconsistent study results may also arise because family size confounds the potentially differential effects that older and younger siblings can have on young children's growth. Additionally, inconsistent results might reflect that the biological significance associated with different growth trajectories is poorly understood. This paper addresses these concerns by tracking children's monthly gains in height and weight from weaning to age five in a high fertility Maya community. We predict that: 1) as an aggregate measure family size will not have a major impact on child growth during the post weaning period; 2) competition from young siblings will negatively impact child growth during the post weaning period; 3) however because of their economic value, older siblings will have a negligible effect on young children's growth. Accounting for parental condition, we use linear mixed models to evaluate the effects that family size, younger and older siblings have on children's growth. Congruent with our expectations, it is younger siblings who have the most detrimental effect on children's growth. While we find statistical evidence of a quantity/quality tradeoff effect, the biological significance of these results is negligible in early childhood. Our findings help to resolve why quantity/quality studies have had inconsistent results by showing that sibling competition varies with sibling age composition, not just family size, and that biological significance is distinct from statistical significance.
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Affiliation(s)
- Karen L. Kramer
- Department of Anthropology, University of Utah, Salt Lake City, Utah 84112, United States of America
| | - Amanda Veile
- Department of Anthropology, Purdue University, West Lafayette, Indiana, United States of America
| | - Erik Otárola-Castillo
- Department of Anthropology, Purdue University, West Lafayette, Indiana, United States of America
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Helfrecht C, Meehan CL. Sibling effects on nutritional status: Intersections of cooperation and competition across development. Am J Hum Biol 2015; 28:159-70. [DOI: 10.1002/ajhb.22763] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Revised: 06/15/2015] [Accepted: 06/17/2015] [Indexed: 11/08/2022] Open
Affiliation(s)
- Courtney Helfrecht
- Department of Anthropology; Washington State University; P.O. Box 4910 Pullman Washington 99164-4910
| | - Courtney L. Meehan
- Department of Anthropology; Washington State University; P.O. Box 4910 Pullman Washington 99164-4910
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Emmons NA, Kelemen DA. I've got a feeling: Urban and rural indigenous children's beliefs about early life mentality. J Exp Child Psychol 2015; 138:106-25. [PMID: 26047086 DOI: 10.1016/j.jecp.2015.05.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 03/03/2015] [Accepted: 05/01/2015] [Indexed: 10/23/2022]
Abstract
This cross-cultural investigation explored children's reasoning about their mental capacities during the earliest period of human physical existence--the prenatal period. For comparison, children's reasoning about the observable period of infancy was also examined. A total of 283 5- to 12-year-olds from two distinct cultures (urban Ecuador and rural indigenous Shuar) participated. Across cultures, children distinguished the fetal period from infancy, attributing fewer capacities to fetuses. However, for both the infancy and fetal periods, children from both cultures privileged the functioning of emotions and desires over epistemic states (i.e., abilities for thought and memory). Children's justifications to questions about fetal mentality revealed that although epistemic states were generally regarded as requiring physical maturation to function, emotions and desires were seen as functioning as a de facto result of prenatal existence and in response to the prospect of future birth and being part of a social group. These results show that from early in development, children across cultures possess nuanced beliefs about the presence and functioning of mental capacities. Findings converge with recent results to suggest that there is an early arising bias to view emotions and desires as the essential inviolable core of human mentality. The current findings have implications for understanding the role that emerging cognitive biases play in shaping conceptions of human mentality across different cultures. They also speak to the cognitive foundations of moral beliefs about fetal rights.
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Affiliation(s)
- Natalie A Emmons
- Department of Psychological and Brain Sciences, Boston University, Boston, MA 02215, USA.
| | - Deborah A Kelemen
- Department of Psychological and Brain Sciences, Boston University, Boston, MA 02215, USA
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Abstract
I present evidence that humans have evolved convergently to social insects with regard to a large suite of social, ecological, and reproductive phenotypes. Convergences between humans and social insects include: (1) groups with genetically and environmentally defined structures; (2) extensive divisions of labor; (3) specialization of a relatively restricted set of females for reproduction, with enhanced fertility; (4) extensive extramaternal care; (5) within-group food sharing; (6) generalized diets composed of high-nutrient-density food; (7) solicitous juveniles, but high rates of infanticide; (8) ecological dominance; (9) enhanced colonizing abilities; and (10) collective, cooperative decision-making. Most of these convergent phenotypic adaptations stem from reorganization of key life-history trade-offs due to behavioral, physiological, and life-historical specializations. Despite their extensive socioreproductive overlap with social insects, humans differ with regard to the central aspect of eusociality: reproductive division of labor. This difference may be underpinned by the high energetic costs of producing offspring with large brains.
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Affiliation(s)
- Bernard Crespi
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada, V5A 1S6,
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Kramer KL. Why what juveniles do matters in the evolution of cooperative breeding. HUMAN NATURE-AN INTERDISCIPLINARY BIOSOCIAL PERSPECTIVE 2015; 25:49-65. [PMID: 24430798 DOI: 10.1007/s12110-013-9189-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The evolution of cooperative breeding is complex, and particularly so in humans because many other life history traits likely evolved at the same time. While cooperative childrearing is often presumed ancient, the transition from maternal self-reliance to dependence on allocare leaves no known empirical record. In this paper, an exploratory model is developed that incorporates probable evolutionary changes in birth intervals, juvenile dependence, and dispersal age to predict under what life history conditions mothers are unable to raise children without adult cooperation. The model's outcome variable (net balance) integrates dependent children's production and consumption as a function of varying life history parameters to estimate the investment mothers or others have to spend subsidizing children. Results suggest that maternal-juvenile cooperation can support the early transition toward a reduction in birth intervals, a longer period of juvenile dependence, and having overlapping young. The need for adult cooperation is most evident when birth intervals are short and age at net production is late. Findings suggest that the needs of juveniles would not have been an early selective force for adult cooperation. Rather, an age-graded division of labor and the mutual benefits of maternal-juvenile cooperation could be an important, but overlooked step in the evolution of cooperative breeding.
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Affiliation(s)
- Karen L Kramer
- Department of Anthropology, University of Utah, Salt Lake City, UT, 02138, USA,
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Meehan CL, Helfrecht C, Quinlan RJ. Cooperative breeding and Aka children's nutritional status: is flexibility key? AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2014; 153:513-25. [PMID: 24452414 DOI: 10.1002/ajpa.22415] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 10/05/2013] [Accepted: 10/11/2013] [Indexed: 11/06/2022]
Abstract
Research suggests that nonmaternal caregivers (allomothers) offer essential assistance through caregiving and provisioning, helping to support lengthy child development. Here, we examine the role of allomothers and the broader social and sharing network on Aka forager children's anthropometrics. We hypothesize that nonmaternal investors strategically target their assistance when it is most needed and when it will have the greatest effect. We evaluate children's nutritional status using WHO standards [weight-for-age (WAZ), height-for-age (HAZ), and weight-for-height (WHZ)] during four periods of child development [early infancy (birth to <9 months), mobility to weaning (9 to <36 months), early childhood (36 to <72 months), and middle childhood (72 to <120 months); N = 127]. We explore the effects of allomothers and the social network across these different risk periods and examine whether the broader social network buffers the loss of a primary allomother. ANOVA results suggest that girls may be experiencing some growth faltering, while boys start smaller and remain small across these stages. We used OLS multiple regression models to evaluate the effects of sex, camp composition, risk periods, and allomothers' presence on WAZ, HAZ, and WHZ. Grandmothers are the most influential allomother, with their effect most evident during the 9 to <36 month period. Camp size was also associated with greater WAZ, suggesting that children residing in small camps may be disadvantaged. Our findings also indicate that, under specific residence patterns, cooperative child rearing networks buffer the loss of a grandmother. Overall, our results suggest the importance of social networks to children's nutritional status and that individuals target investment to critical phases.
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Affiliation(s)
- Courtney L Meehan
- Department of Anthropology, Washington State University, Pullman, WA, 99164-4910
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The effects of residential ecology on patterns of child work and mother's reproductive success among Indo-Fijians. EVOL HUM BEHAV 2013. [DOI: 10.1016/j.evolhumbehav.2013.01.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Nitsch A, Faurie C, Lummaa V. Are elder siblings helpers or competitors? Antagonistic fitness effects of sibling interactions in humans. Proc Biol Sci 2013; 280:20122313. [PMID: 23173210 PMCID: PMC3574445 DOI: 10.1098/rspb.2012.2313] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Accepted: 10/25/2012] [Indexed: 11/27/2022] Open
Abstract
Determining the fitness consequences of sibling interactions is pivotal for understanding the evolution of family living, but studies investigating them across lifetime are lacking. We used a large demographic dataset on preindustrial humans from Finland to study the effect of elder siblings on key life-history traits. The presence of elder siblings improved the chances of younger siblings surviving to sexual maturity, suggesting that despite a competition for parental resources, they may help rearing their younger siblings. After reaching sexual maturity however, same-sex elder siblings' presence was associated with reduced reproductive success in the focal individual, indicating the existence of competition among same-sex siblings. Overall, lifetime fitness was reduced by same-sex elder siblings' presence and increased by opposite-sex elder siblings' presence. Our study shows opposite effects of sibling interactions depending on the life-history stage, and highlights the need for using long-term fitness measures to understand the selection pressures acting on sibling interactions.
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Affiliation(s)
- Aïda Nitsch
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
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Kramer KL. Cooperative Breeding and its Significance to the Demographic Success of Humans. ANNUAL REVIEW OF ANTHROPOLOGY 2010. [DOI: 10.1146/annurev.anthro.012809.105054] [Citation(s) in RCA: 230] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Karen L. Kramer
- Department of Human Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138;
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