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1.
HLA ; 103(3): e15419, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38450972

ABSTRACT

Adoptive cell therapy using virus-specific T cells (VST) is a strategy for treating common opportunistic viral infections after transplantation, particularly when these infections do not resolve through antiviral drug therapy. The availability of third-party healthy donors allows for the immediate use of cells for allogeneic therapy in cases where patients lack an appropriate donor. Here, we present the creation of a cell donor registry of human leukocyte antigen (HLA)-typed blood donors, REDOCEL, a strategic initiative to ensure the availability of compatible cells for donation when needed. Currently, the registry consists of 597 healthy donors with a median age of 29 years, 54% of whom are women. The most represented blood groups were A positive and O positive, with 36.52% and 34.51%, respectively. Also, donors were screened for cytomegalovirus (CMV) and Epstein-Barr virus (EBV). Almost 65% of donors were CMV-seropositive, while less than 5% were EBV-seronegative. Of the CMV-seropositive donors, 98% were also EBV-seropositive. High-resolution HLA-A, -B, -C, -DRB1 and -DQB1 allele and haplotype frequencies were determined in the registry. Prevalent HLA alleles and haplotypes were well represented to ensure donor-recipient HLA-matching, including alleles reported to present viral immunodominant epitopes. Since the functional establishment of REDOCEL, in May 2019, 87 effective donations have been collected, and the effective availability of donors with the first call has been greater than 75%. Thus, almost 89% of patients receiving an effective donation had available at least 5/10 HLA-matched cell donors (HLA-A, -B, -C, -DRB1, and -DQB1). To summarize, based on our experience, a cell donor registry from previously HLA-typed blood donors is a useful tool for facilitating access to VST therapy.


Subject(s)
Cytomegalovirus Infections , Epstein-Barr Virus Infections , Humans , Female , Adult , Male , Blood Banks , Alleles , Herpesvirus 4, Human , Blood Donors , Histocompatibility Antigens Class II , Cytomegalovirus , HLA-A Antigens , T-Lymphocytes
2.
Proc Natl Acad Sci U S A ; 121(9): e2318181121, 2024 Feb 27.
Article in English | MEDLINE | ID: mdl-38346210

ABSTRACT

While it is commonly assumed that farmers have higher, and foragers lower, fertility compared to populations practicing other forms of subsistence, robust supportive evidence is lacking. We tested whether subsistence activities-incorporating market integration-are associated with fertility in 10,250 women from 27 small-scale societies and found considerable variation in fertility. This variation did not align with group-level subsistence typologies. Societies labeled as "farmers" did not have higher fertility than others, while "foragers" did not have lower fertility. However, at the individual level, we found strong evidence that fertility was positively associated with farming and moderate evidence of a negative relationship between foraging and fertility. Markers of market integration were strongly negatively correlated with fertility. Despite strong cross-cultural evidence, these relationships were not consistent in all populations, highlighting the importance of the socioecological context, which likely influences the diverse mechanisms driving the relationship between fertility and subsistence.


Subject(s)
Economics , Fertility , Female , Humans , Population Dynamics , Socioeconomic Factors , Developing Countries
3.
Evol Hum Sci ; 5: e18, 2023.
Article in English | MEDLINE | ID: mdl-37587943

ABSTRACT

Psychological and cultural evolutionary accounts of human sociality propose that beliefs in punitive and monitoring gods that care about moral norms facilitate cooperation. While there is some evidence to suggest that belief in supernatural punishment and monitoring generally induce cooperative behaviour, the effect of a deity's explicitly postulated moral concerns on cooperation remains unclear. Here, we report a pre-registered set of analyses to assess whether perceiving a locally relevant deity as moralistic predicts cooperative play in two permutations of two economic games using data from up to 15 diverse field sites. Across games, results suggest that gods' moral concerns do not play a direct, cross-culturally reliable role in motivating cooperative behaviour. The study contributes substantially to the current literature by testing a central hypothesis in the evolutionary and cognitive science of religion with a large and culturally diverse dataset using behavioural and ethnographically rich methods.

4.
Evol Hum Sci ; 5: e20, 2023.
Article in English | MEDLINE | ID: mdl-37587949

ABSTRACT

Social learning is a critical adaptation for dealing with different forms of variability. Uncertainty is a severe form of variability where the space of possible decisions or probabilities of associated outcomes are unknown. We identified four theoretically important sources of uncertainty: temporal environmental variability; payoff ambiguity; selection-set size; and effective lifespan. When these combine, it is nearly impossible to fully learn about the environment. We develop an evolutionary agent-based model to test how each form of uncertainty affects the evolution of social learning. Agents perform one of several behaviours, modelled as a multi-armed bandit, to acquire payoffs. All agents learn about behavioural payoffs individually through an adaptive behaviour-choice model that uses a softmax decision rule. Use of vertical and oblique payoff-biased social learning evolved to serve as a scaffold for adaptive individual learning - they are not opposite strategies. Different types of uncertainty had varying effects. Temporal environmental variability suppressed social learning, whereas larger selection-set size promoted social learning, even when the environment changed frequently. Payoff ambiguity and lifespan interacted with other uncertainty parameters. This study begins to explain how social learning can predominate despite highly variable real-world environments when effective individual learning helps individuals recover from learning outdated social information.

5.
Proc Natl Acad Sci U S A ; 120(22): e2220124120, 2023 05 30.
Article in English | MEDLINE | ID: mdl-37216525

ABSTRACT

To address claims of human exceptionalism, we determine where humans fit within the greater mammalian distribution of reproductive inequality. We show that humans exhibit lower reproductive skew (i.e., inequality in the number of surviving offspring) among males and smaller sex differences in reproductive skew than most other mammals, while nevertheless falling within the mammalian range. Additionally, female reproductive skew is higher in polygynous human populations than in polygynous nonhumans mammals on average. This patterning of skew can be attributed in part to the prevalence of monogamy in humans compared to the predominance of polygyny in nonhuman mammals, to the limited degree of polygyny in the human societies that practice it, and to the importance of unequally held rival resources to women's fitness. The muted reproductive inequality observed in humans appears to be linked to several unusual characteristics of our species-including high levels of cooperation among males, high dependence on unequally held rival resources, complementarities between maternal and paternal investment, as well as social and legal institutions that enforce monogamous norms.


Subject(s)
Reproduction , Sex Characteristics , Animals , Humans , Female , Male , Marriage , Mammals , Sexual Behavior, Animal
6.
Nat Hum Behav ; 6(11): 1545-1556, 2022 11.
Article in English | MEDLINE | ID: mdl-35851843

ABSTRACT

When interacting with infants, humans often alter their speech and song in ways thought to support communication. Theories of human child-rearing, informed by data on vocal signalling across species, predict that such alterations should appear globally. Here, we show acoustic differences between infant-directed and adult-directed vocalizations across cultures. We collected 1,615 recordings of infant- and adult-directed speech and song produced by 410 people in 21 urban, rural and small-scale societies. Infant-directedness was reliably classified from acoustic features only, with acoustic profiles of infant-directedness differing across language and music but in consistent fashions. We then studied listener sensitivity to these acoustic features. We played the recordings to 51,065 people from 187 countries, recruited via an English-language website, who guessed whether each vocalization was infant-directed. Their intuitions were more accurate than chance, predictable in part by common sets of acoustic features and robust to the effects of linguistic relatedness between vocalizer and listener. These findings inform hypotheses of the psychological functions and evolution of human communication.


Subject(s)
Music , Voice , Humans , Adult , Infant , Speech , Language , Acoustics
7.
Obes Surg ; 32(3): 615-624, 2022 03.
Article in English | MEDLINE | ID: mdl-35048247

ABSTRACT

INTRODUCTION: The impact of laparoscopic sleeve gastrectomy (LSG) on gastroesophageal reflux disease (GERD) has not been widely quantified, and the data in the literature remain controversial. MATERIALS AND METHODS: Candidates for LSG underwent barium swallow, esophageal manometry, ambulatory 24-h esophageal pH monitoring (APM), and gastric emptying scintigraphy before and after surgery (1 and 18 months). Symptoms were evaluated using a gastroesophageal reflux disease questionnaire (GERDq). Esophagogastroduodenoscopy was performed preoperatively in all patients and at 18 months postoperatively in patients who had suffered from preoperative esophagitis. RESULTS: Fifty-two patients were included in the study (64.4% women and 34.6% men) with a median age of 46 years (25-63 years) and BMI of 45.0 ± 5.6 kg/m2. The follow-up rates at 1 and 18 months were 82.7% and 80.8%. At 18 months, the percentage of weight loss (%TWL) was 33.6 ± 10.4% and the percentage of excess BMI loss (%EBMIL) was 77.6 ± 25%. Postoperatively, a significant increase in accelerated gastric emptying and impaired esophageal body motility occurred at 1 and 18 months. A significant worsening of all the values obtained at both 1 and 18 months postoperatively becomes evident when comparing the results of the APM. After surgery, 76.4% of patients had developed "de novo" GERD at 1 month and 41% at 18 months. No improvement was found in patients with symptomatic GERD. CONCLUSION: Based on the results of this study, LSG led to a considerable rate of postoperative "de novo" GERD. In addition, no improvement was found in patients with symptomatic GERD.


Subject(s)
Gastroesophageal Reflux , Laparoscopy , Obesity, Morbid , Esophageal pH Monitoring , Female , Gastrectomy/methods , Gastroesophageal Reflux/surgery , Humans , Laparoscopy/methods , Male , Middle Aged , Obesity, Morbid/surgery
8.
Hum Nat ; 32(1): 208-238, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33881735

ABSTRACT

We examine the opportunities children have for interacting with others and the extent to which they are the focus of others' visual attention in five societies where extended family communities are the norm. We compiled six video-recorded datasets (two from one society) collected by a team of anthropologists and psychologists conducting long-term research in each society. The six datasets include video observations of children among the Yasawas (Fiji), Tanna (Vanuatu), Tsimane (Bolivia), Huatasani (Peru), and Aka (infants and children 4-12 years old; Central African Republic). Each dataset consists of a series of videos of children ranging in age from 2 months to 12 years in their everyday contexts. We coded 998 videos and identified with whom children had opportunities to interact (male and female adults and children) as well as the number of individuals and the proportion of observed time that children spent with these individuals. We also examined the proportion of time children received direct visual gaze (indicating attention to the child). Our results indicate that children less than 5 years old spend the majority of their observed time in the presence of one female adult. This is the case across the five societies. In the three societies from which we have older children (Aka, Yasawa, Peru), we find a clear shift around 5 years of age, with children spending the majority of their time with other children. We also coded the presence or absence of a primary caregiver and found that caregivers remained within 2 ft of target children until 7 years of age. When they were in the company of a primary caregiver, children older than seven spent the majority of their time more than 2 ft from the caregiver. We found a consistent trend across societies with decreasing focal attention on the child with increasing child age. These findings show (1) remarkable consistency across these societies in children's interaction opportunities and (2) that a developmental approach is needed to fully understand human development because the social context is dynamic across the lifespan. These data can serve as a springboard for future research examining social development in everyday contexts.


Subject(s)
Family , Social Behavior , Adolescent , Adult , Caregivers , Child , Child Development , Child, Preschool , Female , Humans , Infant , Male , Social Environment
10.
Dev Sci ; 23(3): e12903, 2020 05.
Article in English | MEDLINE | ID: mdl-31505090

ABSTRACT

Across the lifespan and across populations, humans 'overimitate' causally unnecessary behaviors. Such irrelevant-action imitation facilitates faithful cultural transmission, but its immediate benefits to the imitator are controversial. Over short time scales, irrelevant-action imitation may bootstrap artifact exploration or interpersonal affiliation, and over longer time scales it may facilitate acquisition of either causal models or social conventions. To investigate these putative functions, we recruited community samples from two under-studied populations: Yasawa, Fiji, and Huatasani, Peru. We use a two-action puzzle box: first after a video demonstration, and again one month later. Treating age as a continuous variable, we reveal divergent developmental trajectories across sites. Yasawans (44 adults, M = 39.9 years, 23 women; 42 children, M = 9.8 years, 26 girls) resemble documented patterns, with irrelevant-action imitation increasing across childhood and plateauing in adulthood. In contrast, Huatasaneños (48 adults, M = 37.6 years, 33 women; 47 children, M = 9.3 years, 13 girls) evince a parabolic trajectory: adults at the site show the lowest irrelevant-action imitation of any demographic set in our sample. In addition, all age sets in both populations reduce their irrelevant actions at Time 2, but do not reduce their relevant-action imitation or goal attainment. Taken together, and considering the local cultural contexts, our results suggest that irrelevant-action imitation serves a short-term function and is sensitive to the social context of the demonstration.


Subject(s)
Imitative Behavior , Models, Theoretical , Social Environment , Adult , Age Factors , Child , Child Behavior , Culture , Female , Fiji , Humans , Learning , Male , Peru
11.
Proc Biol Sci ; 286(1898): 20190202, 2019 03 13.
Article in English | MEDLINE | ID: mdl-30836871

ABSTRACT

The emergence of large-scale cooperation during the Holocene remains a central problem in the evolutionary literature. One hypothesis points to culturally evolved beliefs in punishing, interventionist gods that facilitate the extension of cooperative behaviour toward geographically distant co-religionists. Furthermore, another hypothesis points to such mechanisms being constrained to the religious ingroup, possibly at the expense of religious outgroups. To test these hypotheses, we administered two behavioural experiments and a set of interviews to a sample of 2228 participants from 15 diverse populations. These populations included foragers, pastoralists, horticulturalists, and wage labourers, practicing Buddhism, Christianity, and Hinduism, but also forms of animism and ancestor worship. Using the Random Allocation Game (RAG) and the Dictator Game (DG) in which individuals allocated money between themselves, local and geographically distant co-religionists, and religious outgroups, we found that higher ratings of gods as monitoring and punishing predicted decreased local favouritism (RAGs) and increased resource-sharing with distant co-religionists (DGs). The effects of punishing and monitoring gods on outgroup allocations revealed between-site variability, suggesting that in the absence of intergroup hostility, moralizing gods may be implicated in cooperative behaviour toward outgroups. These results provide support for the hypothesis that beliefs in monitoring and punitive gods help expand the circle of sustainable social interaction, and open questions about the treatment of religious outgroups.


Subject(s)
Cooperative Behavior , Interpersonal Relations , Morals , Punishment/psychology , Religion and Psychology , Ethnicity/psychology , Female , Games, Experimental , Humans , Male
12.
Behav Processes ; 161: 73-86, 2019 Apr.
Article in English | MEDLINE | ID: mdl-29859260

ABSTRACT

Despite a shared recognition that the design of the human mind and the design of human culture are tightly linked, researchers in the evolutionary social sciences tend to specialize in understanding one at the expense of the other. The disciplinary boundaries roughly correspond to research traditions that focus more on natural selection and those that focus more on cultural evolution. In this paper, we articulate how two research traditions within the evolutionary social sciences-evolutionary psychology and cultural evolution-approach the study of design. We focus our analysis on the design of cognitive mechanisms that are the result of the interplay of genetic and cultural evolution. We aim to show how the approaches of these two research traditions can complement each other, and provide a framework for developing a wider range of testable hypotheses about cognitive design. To do so, we provide concrete illustrations of how this integrated approach can be used to interrogate cognitive design using examples from our own work on plant and symbolic group boundary cognition. We hope this recognition of different pathways to design will broaden the hypothesis space in the evolutionary social sciences and encourage methodological pluralism in the investigation of the mind.


Subject(s)
Biological Evolution , Cognition , Cultural Evolution , Selection, Genetic , Humans
13.
J Crit Care ; 48: 172-177, 2018 12.
Article in English | MEDLINE | ID: mdl-30216935

ABSTRACT

PURPOSE: Information about immunocompromised patients infected with influenza A (H1N1) virus and requiring admission to the ICU is lacking. Our objective was to know the clinical characteristics of these patients and to identify treatment-related variables associated with mortality. MATERIAL AND METHODS: A prospective multicenter observational cohort study was based on data from a Spanish registry (2009-2015) collected by 148 Spanish ICUs. All patients admitted to the ICU with the diagnosis of influenza A (H1N1) virus infection were included. Immunosuppression was clearly defined. Factors associated with mortality in immunocompromised patients were assessed by conventional logistic regression analysis and by a propensity score (PS) adjusted-multivariable analysis. RESULTS: Of 1899 patients with influenza A (H1N1) infection, 238 (12.5%) were classified as immunocompromised. Mortality was significantly higher in immunosuppressed patients. Four variables independently associated with mortality were identified: SOFA score, need of vasopressor, use of corticosteroids, and acute renal failure, AKIN 3 stage. In the PS-adjusted model, corticosteroid therapy remained as an independent factor associated with increased mortality (OR 2.25;95%CI, 1.15-4.38;p = 0.017). In the subgroup of hematological patients (n = 141), corticosteroid therapy was also associated with increased mortality (OR 3.12; 95%CI, 1.32-7.41; p = 0.010). CONCLUSION: Immunocompromised individuals with influenza A (H1N1) admitted to the ICU have a poor outcome. In this population, the use of corticosteroids is strongly discouraged.


Subject(s)
Immunocompromised Host , Influenza A Virus, H1N1 Subtype , Influenza, Human/mortality , Adult , Aged , Cohort Studies , Female , Hospitalization , Humans , Intensive Care Units , Logistic Models , Male , Middle Aged , Organ Dysfunction Scores , Prospective Studies , Registries , Risk Factors , Spain
14.
Stem Cell Res ; 16(3): 635-9, 2016 05.
Article in English | MEDLINE | ID: mdl-27346196

ABSTRACT

From 106 human blastocyts donate for research after in vitro fertilization (IVF) and preimplantation genetic diagnosis (PGD) for monogenetic disorder, 3 human embryonic stem cells (hESCs) HVR1, HVR2 and HVR3 were successfully derived. HVR1 was assumed to be genetically normal, HVR2 carrying Becker muscular dystrophy and HVR3 Hemophilia B. Despite the translocation t(9;15)(q34.3;q14) detected in HVR2, all the 3 cell lines were characterised in vitro and in vivo as normal hESCs lines and were registered in the Spanish Stem Cell Bank.


Subject(s)
Hemophilia B/diagnosis , Human Embryonic Stem Cells/cytology , Muscular Dystrophies/diagnosis , Animals , Blastocyst/cytology , Cell Differentiation , Cells, Cultured , Cellular Reprogramming , Chromosomes, Human, Pair 15 , Chromosomes, Human, Pair 9 , Female , Fertilization in Vitro , Hemophilia B/genetics , Human Embryonic Stem Cells/metabolism , Human Embryonic Stem Cells/transplantation , Humans , Karyotype , Male , Mice , Mice, SCID , Microscopy, Fluorescence , Muscular Dystrophies/genetics , Preimplantation Diagnosis , Teratoma/metabolism , Teratoma/pathology , Translocation, Genetic
15.
Philos Trans R Soc Lond B Biol Sci ; 371(1692): 20150149, 2016 Apr 19.
Article in English | MEDLINE | ID: mdl-27022076

ABSTRACT

Several empirical observations suggest that when women have more autonomy over their reproductive decisions, fertility is lower. Some evolutionary theorists have interpreted this as evidence for sexual conflicts of interest, arguing that higher fertility is more adaptive for men than women. We suggest the assumptions underlying these arguments are problematic: assuming that women suffer higher costs of reproduction than men neglects the (different) costs of reproduction for men; the assumption that men can repartner is often false. We use simple models to illustrate that (i) menorwomen can prefer longer interbirth intervals (IBIs), (ii) if men can only partner with wives sequentially they may favour shorter IBIs than women, but such a strategy would only be optimal for a few men who can repartner. This suggests that an evolved universal male preference for higher fertility than women prefer is implausible and is unlikely to fully account for the empirical data. This further implies that if women have more reproductive autonomy, populations should grow, not decline. More precise theoretical explanations with clearly stated assumptions, and data that better address both ultimate fitness consequences and proximate psychological motivations, are needed to understand under which conditions sexual conflict over reproductive timing should arise.


Subject(s)
Fertility , Models, Biological , Reproductive Behavior/psychology , Women's Health , Choice Behavior , Family Characteristics , Female , Humans , Male , Survival Rate
16.
J Assist Reprod Genet ; 33(5): 617-626, 2016 May.
Article in English | MEDLINE | ID: mdl-26945754

ABSTRACT

PURPOSE: Baboons are commonly utilized as an animal model for studies of human reproduction. However, folliculogenesis in this species has not been fully documented. The aim of this study was to assess follicle morphometry and expression of essential proteins involved in folliculogenesis in baboons. METHODS: Ovaries were recovered from four adult baboons and processed for histological evaluation and immunohistochemical analyses. Follicle proportion, follicle and oocyte diameter, theca layer thickness, number of granulosa cells, and follicle density were calculated. Immunohistochemical staining was also carried out for connexin 43 (Cx43), aromatase, and zona pellucida 3 (ZP3). RESULTS: A total of 2221 follicles were counted and measured. Proportions of primordial, primary, secondary, small antral, and large antral follicles were 49, 26, 23, 1, and 1 %, respectively. The increase in follicle diameter was due not only to the increase in oocyte diameter but also to granulosa cell proliferation. Almost all antral follicles were positive for Cx43 (89.8 %), aromatase (84.8 %), and ZP3 (100 %). Most secondary follicles were positive for Cx43 (65 %) and ZP3 (64.5 %), and some primary follicles were positive only for Cx43. No primordial follicles stained positive in any of these immunohistochemical analyses. Only antral follicles showed aromatase activity. CONCLUSIONS: On the basis of these results, we can conclude that folliculogenesis in baboons appears to be similar to that in humans, and this animal therefore constitutes a valuable model.


Subject(s)
Ovarian Follicle/growth & development , Ovary/metabolism , Papio anubis , Animals , Cell Size , Female , Granulosa Cells/cytology , Granulosa Cells/metabolism , Immunohistochemistry , Ovary/cytology , Theca Cells/cytology , Theca Cells/metabolism
17.
Curr Opin Psychol ; 8: 112-118, 2016 Apr.
Article in English | MEDLINE | ID: mdl-29506785

ABSTRACT

While most psychologists recognize the importance of genes and culture in shaping human cognition, few theoretical perspectives in the field offer a framework for understanding their relationship and for deriving predictions about the structure of the variation we see across space and time. Here we argue that culture-gene coevolutionary (CGC) frameworks have such potential, and can unite disparate fields across the social sciences and sub-fields within psychology. We illustrate the power of this functionalist evolutionary approach by reviewing recent research on three interlinked topics; cultural learning rules, language cognition, and reasoning about ethnic social groups. We show how CGC approaches complement, and contrast with, traditional approaches in psychology on these topics. Furthermore, this theoretical framework has already been fruitful in drawing new predictions and pointing to new directions of inquiry.

18.
Top Cogn Sci ; 7(4): 595-610, 2015 Oct.
Article in English | MEDLINE | ID: mdl-26417672

ABSTRACT

Using samples from three diverse populations, we test evolutionary hypotheses regarding how people reason about the inheritance of various traits. First, we provide a framework for differentiat-ing the outputs of mechanisms that evolved for reasoning about variation within and between (a) biological taxa and (b) culturally evolved ethnic categories from (c) a broader set of beliefs and categories that are the outputs of structured learning mechanisms. Second, we describe the results of a modified "switched-at-birth" vignette study that we administered among children and adults in Puno (Peru), Yasawa (Fiji), and adults in the United States. This protocol permits us to study perceptions of prenatal and social transmission pathways for various traits and to differentiate the latter into vertical (i.e., parental) versus horizontal (i.e., peer) cultural influence. These lines of evidence suggest that people use all three mechanisms to reason about the distribution of traits in the population. Participants at all three sites develop expectations that morphological traits are under prenatal influence, and that belief traits are more culturally influenced. On the other hand, each population holds culturally specific beliefs about the degree of social influence on non-morphological traits and about the degree of vertical transmission-with only participants in the United States expecting parents to have much social influence over their children. We reinterpret people's differentiation of trait transmission pathways in light of humans' evolutionary history as a cultural species.


Subject(s)
Cognition/physiology , Learning/physiology , Quantitative Trait, Heritable , Thinking/physiology , Adolescent , Adoption/psychology , Adult , Aged , Biological Evolution , Child , Child, Preschool , Cross-Cultural Comparison , Cultural Evolution , Female , Fiji , Humans , Male , Middle Aged , Peru , United States , Wills/psychology , Young Adult
19.
Hum Nat ; 26(1): 1-27, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25731969

ABSTRACT

Many accounts of ethnic phenomena imply that processes such as stereotyping, essentialism, ethnocentrism, and intergroup hostility stem from a unitary adaptation for reasoning about groups. This is partly justified by the phenomena's co-occurrence in correlational studies. Here we argue that these behaviors are better modeled as functionally independent adaptations that arose in response to different selection pressures throughout human evolution. As such, different mechanisms may be triggered by different group boundaries within a single society. We illustrate this functionalist framework using ethnographic work from the Quechua-Aymara language boundary in the Peruvian Altiplano. We show that different group boundaries motivate different ethnic phenomena. For example, people have strong stereotypes about socioeconomic categories, which are not cooperative units, whereas they hold fewer stereotypes about communities, which are the primary focus of cooperative activity. We also show that, despite the cross-cultural importance of ethnolinguistic boundaries, the Quechua-Aymara linguistic distinction does not strongly motivate any of these intergroup processes.


Subject(s)
Indians, South American/psychology , Stereotyping , Adult , Cognition/physiology , Cooperative Behavior , Culture , Female , Group Processes , Hostility , Humans , Indians, South American/genetics , Language , Male , Personal Satisfaction , Peru/ethnology , Selection, Genetic/genetics , Social Identification , Socioeconomic Factors
20.
PeerJ ; 2: e512, 2014.
Article in English | MEDLINE | ID: mdl-25165627

ABSTRACT

Background. Parental absences in childhood are often associated with accelerated reproductive maturity in humans. These results are counterintuitive for evolutionary social scientists because reductions in parental investment should be detrimental for offspring, but earlier reproduction is generally associated with higher fitness. In this paper we discuss a neglected hypothesis that early reproduction is often associated with parental absence because it decreases the average relatedness of a developing child to her future siblings. Family members often help each other reproduce, meaning that parents and offspring may find themselves in competition over reproductive opportunities. In these intergenerational negotiations offspring will have less incentive to help the remaining parent rear future half-siblings relative to beginning reproduction themselves. Method. We illustrate this "intergenerational conflict hypothesis" with a formal game-theoretic model. Results. We show that when resources constrain reproductive opportunities within the family, parents will generally win reproductive conflicts with their offspring, i.e., they will produce more children of their own and therefore delay existing offsprings' reproduction. This is due to the asymmetric relatedness between grandparents and grandchildren (r = .25), compared to siblings (r = 0.5), resulting in greater incentives for older siblings to help rear younger siblings than for grandparents to help rear grandchildren. However, if a parent loses or replaces their partner, the conflict between the parent and offspring becomes symmetric since half siblings are as related to one another as grandparents are to grandchildren. This means that the offspring stand to gain more from earlier reproduction when their remaining parent would produce half, rather than full, siblings. We further show that if parents senesce in a way that decreases the quality of their infant relative to their offspring's infant, the intergenerational conflict can shift to favor the younger generation.

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