scholarly journals Religious celibacy brings kin-selected benefits

2021 ◽  
Author(s):  
Alberto Micheletti ◽  
Erhao Ge ◽  
Liqiong Zhou ◽  
Yuan Chen ◽  
Hanzhi Zhang ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Inclusive Fitness ◽  
Cultural Practice ◽  
Western China ◽  
Costs And Benefits ◽  
Fitness Costs ◽  
Individual Control ◽  
Sociodemographic Data ◽  
Parental Preferences

The influence of inclusive fitness interests on the evolution of human institutions remains unclear. Religious celibacy constitutes an especially puzzling institution, often deemed maladaptive. Here, we present sociodemographic data from an agropastoralist Buddhist population in western China, where parents sometimes sent a son to the monastery. We find that men with a monk brother father more children, and grandparents with a monk son have more grandchildren, suggesting that the practice is adaptive. We develop a model of celibacy to elucidate the inclusive fitness costs and benefits associated with this behaviour. We show that a minority of sons can be favoured to be celibate if this increases their brothers’ reproductive success, but only if the decision is under parental, rather than individual, control. These conditions apply to monks in our study site. Inclusive fitness considerations appear to play a key role in shaping parental preferences to adopt this cultural practice.

What Is Fitness?

2015 ◽  
Author(s):  
James A.R. Marshall
Keyword(s):  
Reproductive Success ◽  
Inclusive Fitness ◽  
Structured Populations ◽  
Reproductive Value ◽  
Costs And Benefits ◽  
Risk Of Death ◽  
Fitness Effects ◽  
Inclusive Fitness Theory ◽  
Definition Of ◽  
Evolutionary Fitness

This chapter considers the problem of correctly defining fitness costs and benefits in inclusive fitness theory, when competition occurs between offspring who are relatives. It reviews the definition of evolutionary fitness and shows how its misinterpretation explains many previous misunderstandings as to whether inclusive fitness theory always makes accurate predictions. The chapter begins with a discussion of Haldane's dilemma, which can be formalized with fitness equations that show that the risk of death can make fitness effects all-or-nothing. It then examines how inclusive fitness models can be constructed to deal with reproductive value and class-structured populations. It also shows how costs and benefits can be expressed as payoffs that are proportional to reproductive success, as changes in production of offspring, or as changes in evolutionary fitness. Finally, it presents examples that illustrate when fitness, payoffs, and fecundity are different, and how inclusive fitness analyses can be performed properly in such situations.

Reproductive Autonomy and Evolutionary Biology: A Regulatory Framework for Trait-Selection Technologies

1993 ◽  
Vol 19 (3) ◽  
pp. 187-231
Author(s):  
Owen D. Jones
Keyword(s):  
Reproductive Success ◽  
Supreme Court ◽  
Reproductive Strategies ◽  
Evolutionary Biology ◽  
Social Values ◽  
Inclusive Fitness ◽  
Regulatory System ◽  
Regulatory Framework ◽  
Reproductive Autonomy ◽  
Future Child

The Constitution protects, in some measure, each person's autonomy in making basic decisions about family, parenthood, and procreation. This Article examines the extent to which courts should protect from government intrusions a parent's access to technologies that influence specific characteristics of offspring. Beginning with Supreme Court opinions that articulate constitutional and social values regarding reproductive autonomy, the Article explores how important new insights from evolutionary biology may supplement an understanding of Human procreation. Specifically, the Article explains how trait selection can constitute an important part of larger “reproductive strategies” that powerfully affect an individual's “inclusive fitness” (itself a measure of reproductive success). It concludes that access to trait-selection technologies should receive the same federal protection from government intrusions as that afforded access to abortion. It proposes the first limit to that protection, however, when a parent seeks to select for a trait, or to use a technique, that would be clearly and significantly damaging to the future child. The Article subsequently divides the use of trait-selection technologies (TSTs) into eight contexts and proposes a preliminary framework by which a regulatory system could legitimately distinguish among them.

Rhinella icterica and Rhinella ornata (Anura: Bufonidae) tadpoles do not recognise siblings

2021 ◽  
pp. 214-220
Author(s):  
Alexandre Polettini Neto
Keyword(s):  
Environmental Factors ◽  
Laboratory Experiments ◽  
Inclusive Fitness ◽  
Costs And Benefits ◽  
Environmental Characteristics ◽  
Ecological Processes ◽  
Aggregation Behaviour ◽  
Rearing Methods

Benefits conferred to animals living in groups may be greater if groups are formed by relatives rather than non-relatives, because cooperating with relatives increases the probability of their own genes being passed on to group offspring (inclusive fitness). Non-social aggregations are formed in response to environmental characteristics, while social aggregations are formed from the attraction among individuals. The attraction or repulsion between individuals is mediated by recognition mechanisms, which mediate important ecological processes and behaviours. Here, we conducted laboratory experiments to test if tadpoles of two sympatric bufonids, Rhinella icterica and R. ornata, are able to recognise siblings. We collected eggs of the two species in the field and raised them in laboratory settings, according to three different methods: siblings and non-siblings reared in separated containers; siblings and non-siblings reared in the same container separated by a plastic net; and eggs from the same spawn reared separately, each one in an individual container. Later, we tested if tadpoles could choose between groups of siblings and non-siblings. The results indicate that tadpoles of neither species were able to discriminate between siblings and non-siblings, regardless of the rearing methods. Therefore, kinship is less important than environmental factors in tadpole aggregation behaviour of these species, and it may be dependent on the balance between costs and benefits. Our results can be used as a start point to better understand tadpole aggregation behaviour and recognition mechanisms in these species.

scholarly journals OPPOSITION TO INBREEDING AMONG CLOSE KIN

2018 ◽  
Author(s):  
Jan Antfolk ◽  
Debra Lieberman ◽  
Christopher Harju ◽  
Anna Albrecht ◽  
Andreas Mokros ◽  
...  
Keyword(s):  
Inclusive Fitness ◽  
Large Population ◽  
Self Regulation ◽  
Family Members ◽  
Indirect Costs ◽  
Population Based ◽  
Fitness Costs ◽  
Inclusive Fitness Theory ◽  
The Difference ◽  
Close Relatives

Due to the intense selection pressure against inbreeding, humans are expected to possess psychological adaptations that regulate mate choice and avoid inbreeding. From a gene’s-eye perspective, there is little difference in the evolutionary costs between situations where an individual him/herself is participating in inbreeding and inbreeding among other close relatives. The difference is merely quantitative, as fitness can be compromised via both routes. The question is whether humans are sensitive to the direct as well as indirect costs of inbreeding. Using responses from a large population-based sample (27,364 responses from 2,353 participants), we found that human motivations to avoid inbreeding closely track the theoretical costs of inbreeding as predicted by inclusive-fitness theory. Participants were asked to select in a forced choice paradigm, which of two acts of inbreeding with actual family members they would want to avoid most. We found that the estimated fitness costs explained 83.6% of participant choices. Importantly, fitness costs explained choices also when the self was not involved. We conclude that humans intuit the indirect fitness costs of mating decisions made by close family members and that psychological inbreeding avoidance mechanisms extend beyond self-regulation.

scholarly journals Serial monogamy benefits both sexes in the biparental convict cichlid

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6535 ◽  
Author(s):  
Jennifer L. Snekser ◽  
Murray Itzkowitz
Keyword(s):  
Reproductive Success ◽  
Brood Size ◽  
Parental Behavior ◽  
Convict Cichlid ◽  
Costs And Benefits ◽  
Serial Monogamy ◽  
Convict Cichlids ◽  
Amatitlania Nigrofasciata ◽  
Males And Females

Monogamy can be either long-term or serial, with new pairs formed with each breeding bout. Costs and benefits are associated with each strategy. Because biparental convict cichlids (Amatitlania nigrofasciata) typically switch mates, exhibiting serial monogamy, we tested for the costs associated with forcing individuals to remain with the same mate. Convict cichlids were observed over two successive breeding bouts, either with the same or a new, equally experienced, mate. Parental behavior did not differ between breeding bouts, nor did brood size. Surprisingly, fish that remained with their original partner for a second bout took significantly longer to produce a brood compared to fish that paired with new partners. New partners were also more likely to successfully produce a second brood than re-mated partners. This is in contrast to the majority of bird studies that show many benefits to staying with the same partner for multiple broods. In convict cichlids, there seems to be no benefit associated with remaining with the same partner and switching mates reduces duration between broods for both males and females, potentially increasing overall reproductive success.

scholarly journals Males harm females less when competing with familiar relatives

2017 ◽  
Vol 284 (1867) ◽  
pp. 20171984 ◽  
Author(s):  
Samuel J. Lymbery ◽  
Leigh W. Simmons
Keyword(s):  
Egg Production ◽  
Callosobruchus Maculatus ◽  
Genetic Relatedness ◽  
Inclusive Fitness ◽  
Fitness Costs ◽  
Offspring Production ◽  
Social Familiarity ◽  
Indirect Fitness ◽  
Opposite Sex ◽  
Female Lifespan

Sexual conflict occurs when reproductive partners have different fitness optima, and can lead to the evolution of traits in one sex that inflict fitness costs on the opposite sex. Recently, it has been proposed that antagonism by males towards females should be reduced when they compete with relatives, because reducing the future productivity of a female would result in an indirect fitness cost for a harmful male. We tested this prediction in the seed beetle Callosobruchus maculatus , the males of which harm females with genital spines and pre-copulatory harassment. We compared lifespan, lifetime egg production and lifetime offspring production among females housed with groups of males that varied in their familiarity and relatedness. Females produced significantly more eggs and offspring when grouped with males who were both related and familiar to each other. There was no effect of male relatedness or familiarity on female lifespan. Our results suggest that males plastically adjust their harmfulness towards females in response to changes in inclusive fitness payoffs, and that in this species both genetic relatedness and social familiarity mediate this effect.

Human inbreeding avoidance: Culture in nature

1983 ◽  
Vol 6 (1) ◽  
pp. 91-102 ◽  
Author(s):  
Pierre L. van den Berghe
Keyword(s):  
Inbreeding Depression ◽  
Critical Period ◽  
Clinical Evidence ◽  
Inclusive Fitness ◽  
Inbreeding Avoidance ◽  
Fitness Costs ◽  
Optimal Balance ◽  
Social Animals ◽  
Close Inbreeding ◽  
Cultural Rules

AbstractMuch clinical and ethnographic evidence suggests that humans, like many other organisms, are selected to avoid close inbreeding because of the fitness costs of inbreeding depression. The proximate mechanism of human inbreeding avoidance seems to be precultural, and to involve the interaction of genetic predispositions and environmental conditions. As first suggested by E. Westermarck, and supported by evidence from Israeli kibbutzim, Chinese sim-pua marriage, and much convergent ethnographic and clinical evidence, humans negatively imprint on intimate associates during a critical period of early childhood (between ages 2 and 6).There is also much evidence that, like other social animals, humans do not seek to maximize outbreeding, but rather to maintain an optimal balance between outbreeding and inbreeding.Closeinbreeding reduces fitness through inbreeding depression, butsomeinbreeding brings the benefits of nepotism. For simple, stateless, horticultural societies, the optimal balance seems to be achieved by a combination of precultural inbreeding avoidance of relatives with anr≤·25 and cultural rules of preferential marriage with kin withr≥·25. Adjustment of the coefficient of inbreeding to other ecological settings seems to be largely cultural. An interactive model of “culture in nature” is presented, in which culture is seen as coevolving with genes to produce the maxiniization of individual inclusive fitness.

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