scholarly journals Life–history theory, fertility and reproductive success in humans

2002 ◽  
Vol 269 (1491) ◽  
pp. 553-562 ◽  
Author(s):  
Beverly I Strassmann ◽  
Brenda Gillespie
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Life History Theory

Examining the link between religiousness and fitness in a behavioural ecological framework

2019 ◽  
Vol 52 (5) ◽  
pp. 756-767 ◽  
Author(s):  
Janko Međedović
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Parental Investment ◽  
Life History Theory ◽  
Community Sample ◽  
Future Research ◽  
Harsh Environment ◽  
Age At First Birth ◽  
First Birth ◽  
Number Of Children

AbstractIn recent years there have been attempts to explain religiousness from an evolutionary viewpoint. However, empirical data on this topic are still lacking. In the present study, the behavioural ecological theoretical framework was used to explore the relations between religiousness, harsh environment, fitness (reproductive success and parental investment) and fitness-related outcomes (age at first birth, desired number of children and the romantic relationship duration). The data were collected from 461 individuals from a community sample who were near the end of their reproductive phase (54% females, Mage = 51.75; SD = 6.56). Positive links between religiousness, harsh environment, fitness and fitness-related outcomes were expected, with the exception of age at first birth, for which a negative association was hypothesized. Hence, the main assumption of the study was that religiousness has some attributes of fast life-history phenotypes – that it emerges from a harsh environment and enables earlier reproduction. The study findings partially confirmed these hypotheses. Religiousness was positively related to environmental harshness but only on a zero-order level. Religious individuals had higher reproductive success (this association was especially pronounced in males) but religiousness did not show associations with parental investment. Religiousness was positively associated with desired number of children and negatively associated with age at first birth, although the latter association was only marginally significant in the multivariate analyses. Finally, path analysis showed that desired number of children and age at first birth completely mediated the relation between religiousness and reproductive success. The data confirmed the biologically adaptive function of religiousness in contemporary populations and found the mediating processes that facilitate fitness in religious individuals. Furthermore, the findings initiate a more complex view of religiousness in a life-history context which could be fruitful for future research: a proposal labelled as ‘ontogeny-dependent life-history theory of religiousness’.

scholarly journals Age-based soldier polyethism: old termite soldiers take more risks than young soldiers

2018 ◽  
Vol 14 (3) ◽  
pp. 20180025 ◽  
Author(s):  
Saki Yanagihara ◽  
Wataru Suehiro ◽  
Yuki Mitaka ◽  
Kenji Matsuura
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Life Expectancy ◽  
Task Allocation ◽  
Life History Theory ◽  
Nest Defence ◽  
Front Line ◽  
Age Dependent ◽  
Predatory Ants ◽  
Termite Soldiers

Who should take on risky tasks in an age-heterogeneous society? Life-history theory predicts that, in social insects, riskier tasks should be undertaken by sterile individuals with a shorter life expectancy. The loss of individuals with shorter life expectancy is less costly for colony reproductive success than the loss of individuals with longer life expectancy. Termite colonies have a sterile soldier caste, specialized defenders engaged in the most risky tasks. Here we show that termite soldiers exhibit age-dependent polyethism, as old soldiers are engaged in front-line defence more than young soldiers. Our nest defence experiment showed that old soldiers went to the front line and blocked the nest opening against approaching predatory ants more often than young soldiers. We also found that young soldiers were more biased toward choosing central nest defence as royal guards than old soldiers. These results demonstrate that termite soldiers have age-based task allocation, by which ageing predisposes soldiers to switch to more dangerous tasks. This age-dependent soldier task allocation increases the life expectancy of soldiers, allowing them to promote their lifetime contribution to colony reproductive success.

scholarly journals Reproductive ecology of short and long-term mating: implications for sexual selection and life history theory

2020 ◽  
Author(s):  
Janko Mileta Međedović
Keyword(s):  
Sexual Selection ◽  
Life History ◽  
Reproductive Success ◽  
Life History Theory ◽  
Human Life ◽  
Reproductive Ecology ◽  
Mating Patterns ◽  
Number Of Children ◽  
Human Reproductive

Mating patterns are crucial for understanding selection regimes in current populations and highly implicative for sexual selection and life history theory. However, empirical data on the relations between mating and fitness-related outcomes in contemporary humans are lacking. In the present research we examined the sexual selection on mating (with an emphasis on Bateman’s third parameter – the association between mating and reproductive success) and life history dynamics of mating by examining the relations between mating patterns and a comprehensive set of variables which determine human reproductive ecology. We conducted two studies (Study 1: N=398, Mage=31.03; Study 2: N=996, Mage=40.81, the sample was representative for participants’ sex, age, region, and settlement size). The findings from these studies were mutually congruent and complementary. In general, the data suggested that short-term mating was unrelated or even negatively related to reproductive success. Conversely, long-term mating was positively associated with reproductive success and there were indices that the beneficial role of long-term mating is more pronounced in males, which is in accordance with Bateman’s third principle. Observed age of first reproduction fully mediated the link between long-term mating and number of children but only in male participants. There were no clear indications of the position of the mating patterns in human life history trajectories; however, the obtained data suggested that long-term mating has some characteristics of fast life history dynamics. Findings are implicative for sexual selection and life history theory in humans.

scholarly journals Time spent in distinct life-history stages has sex-specific effects on reproductive fitness in wild Atlantic salmon

2019 ◽  
Author(s):  
Kenyon B. Mobley ◽  
Hanna Granroth-Wilding ◽  
Mikko Ellmen ◽  
Panu Orell ◽  
Jaakko Erkinaro ◽  
...  
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Atlantic Salmon ◽  
Marine Environment ◽  
Mating Success ◽  
Life History Theory ◽  
Reproductive Fitness ◽  
Life Cycles ◽  
Male Mating ◽  
Life History Stages

AbstractIn species with complex life cycles, life history theory predicts that fitness is affected by conditions encountered in previous life history stages. Here, we use a four-year pedigree to investigate if time spent in two distinct life history stages has sex-specific reproductive fitness consequences in anadromous Atlantic salmon (Salmo salar). We determined the amount of years spent in fresh water as juveniles (freshwater age, FW), and years spent in the marine environment prior to sexual maturation (sea age, SW) on 264 spawning adults. We then estimated reproductive fitness as the number of offspring (reproductive success) and the number of mates (mating success) using genetic parentage analysis (>5000 offspring). Sea age is positively correlated with reproductive and mating success of both sexes whereby older and larger individuals gained the highest reproductive fitness benefits (females: increase of 16.5 offspring/SW and 0.86 mates/SW; males: increase of 12.4 offspring/SW and 0.43 mates/SW). Younger freshwater age was related to older sea age and thus increased reproductive fitness, but only among females (females: −9.0 offspring/FW and −0.80 mates/FW). This implies that females can obtain higher reproductive fitness by transitioning to the marine environment earlier. In contrast, male mating and reproductive success was unaffected by freshwater age and males returned to spawn earlier than females despite the fitness advantage of later sea age maturation. Our results show that the timing of transitions between juvenile and adult phases has a sex-specific consequence on female reproductive fitness, demonstrating a life-history trade-off between maturation and reproduction in wild Atlantic salmon.

scholarly journals Phenotypic Signals of Sexual Selection and Fast Life History Dynamics for the Long-Term but Not Short-Term Mating

2021 ◽  
Vol 19 (4) ◽  
pp. 147470492110571
Author(s):  
Janko Međedović
Keyword(s):  
Sexual Selection ◽  
Life History ◽  
Reproductive Success ◽  
Life History Theory ◽  
Human Life ◽  
Short Term ◽  
Mating Patterns ◽  
Number Of Children ◽  
Human Reproductive

Mating patterns are crucial for understanding selection regimes in current populations and highly implicative for sexual selection and life history theory. However, empirical data on the relations between mating and reproductive outcomes in contemporary humans are lacking. In the present research we examined the sexual selection on mating (with an emphasis on Bateman's third parameter – the association between mating and reproductive success) and life history dynamics of mating by examining the relations between mating patterns and a comprehensive set of variables which determine human reproductive ecology. We conducted two studies (Study 1: N = 398, Study 2: N = 996, the sample was representative for participants’ sex, age, region, and settlement size). The findings from these studies were mutually congruent and complementary. In general, the data suggested that short-term mating was unrelated or even negatively related to reproductive success. Conversely, long-term mating was positively associated with reproductive success (number of children in Study 1; number of children and grandchildren in Study 2) and there were indices that the beneficial role of long-term mating is more pronounced in males, which is in accordance with Bateman's third principle. Observed age of first reproduction mediated the link between long-term mating and number of children but only in male participants (Study 2). There were no clear indications of the position of the mating patterns in human life history trajectories; however, the obtained data suggested that long-term mating has some characteristics of fast life history dynamics. Findings are implicative for sexual selection and life history theory in humans.

Interrelationships of factors of social development are more complex than Life History Theory predicts

2019 ◽  
Vol 42 ◽  
Author(s):  
Boris Kotchoubey
Keyword(s):  
Life History ◽  
Social Development ◽  
Life History Theory ◽  
Strong Correlations ◽  
Behavioral Features

Abstract Life History Theory (LHT) predicts a monotonous relationship between affluence and the rate of innovations and strong correlations within a cluster of behavioral features. Although both predictions can be true in specific cases, they are incorrect in general. Therefore, the author's explanations may be right, but they do not prove LHT and cannot be generalized to other apparently similar processes.

scholarly journals Five reasons COVID-19 is less severe in younger age groups

2020 ◽  
Author(s):  
Paul W Turke
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Age Of Onset ◽  
Age Groups ◽  
Medical Community ◽  
System Function ◽  
The Third ◽  
Immune System Function ◽  
Age Related ◽  
Younger Age

Abstract The severity of COVID-19 is age-related, with the advantage going to younger age groups. Five reasons are presented. The first two are well-known, are being actively researched by the broader medical community, and therefore are discussed only briefly here. The third, fourth, and fifth reasons derive from evolutionary life history theory, and potentially fill gaps in current understanding of why and how young and old age groups respond differently to infection with SARS-CoV-2. Age of onset of generalized somatic aging, and the timing of its progression, are identified as important causes of these disparities, as are specific antagonistic pleiotropic tradeoffs in immune system function.

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