scholarly journals Height, Age at First Birth, and Lifetime Reproductive Success: A Prospective Cohort Study of Finnish Male and Female Twins

2013 ◽  
Vol 16 (2) ◽  
pp. 581-589 ◽  
Author(s):  
Karri Silventoinen ◽  
Samuli Helle ◽  
Jessica Nisén ◽  
Pekka Martikainen ◽  
Jaakko Kaprio
Keyword(s):  
Reproductive Success ◽  
Short Stature ◽  
Genetic Factors ◽  
Family Background ◽  
Lifetime Reproductive Success ◽  
Age At First Birth ◽  
First Birth ◽  
Individual Level ◽  
Number Of Children ◽  
The Third

The associations between height and reproductive success in humans have attracted long-time scientific interest, but in addition to rather mixed previous results, little is still known about the background mechanisms of these associations. We analyzed the association of adult height with age at first birth and lifetime reproductive success using a twin study design that is able to optimally take into account family background and estimate the contributions of genetic and environmental factors. Information on live births as of June 2009 for 7,830 Finnish twins born 1950–1957 was extracted from the national population register. We found evidence for non-linear associations in men, as men in the third sex-specific height quintile had the highest probability of having one to two children, or three or more children at individual level analyses, and also to have any children when analyzing twin pairs discordant for height. Furthermore, the probability of having a spouse was highest in the third height category in men. Short stature was associated with earlier age at first birth in females, explained by correlated genetic factors, but not with lifetime number of children or having a spouse. Our results suggest that average stature may give some advantage for reproduction in males. In females, genetic factors explained the association between short stature and young age at first birth, which may suggest the role of hormonal factors.

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 Intelligence and Fitness: The Mediating Role of Educational Level

2017 ◽  
Vol 15 (2) ◽  
pp. 147470491770693 ◽  
Author(s):  
Janko Međedović
Keyword(s):  
Reproductive Success ◽  
Cognitive Abilities ◽  
Evolutionary Status ◽  
Age At First Birth ◽  
First Birth ◽  
Short Term ◽  
Number Of Children ◽  
Mediating Role ◽  
Fitness Indicators

The evolutionary status of intelligence is not clear: It is positively related to various indicators of fitness but negatively to reproductive success as the most important fitness marker. In the present research, we explored the links between intelligence and three fitness indicators: number of children (short-term reproductive success), number of grandchildren (long-term reproductive success), and age at first birth. Participants were individuals in a postreproductive stage ( N = 191; mean age = 66.5 years). Intelligence had a positive correlation with short-term reproductive success and age at first birth but a negative correlation with long-term reproductive success. Participants’ education turned out to be a significant mediator of the link between intelligence and criterion measures. The results showed that intelligence can elevate short-term reproductive success. Furthermore, individuals with higher intellectual abilities tended to delay reproduction, which negatively affected their long-term reproductive success. Education was revealed as a very important resource which affects the link between cognitive abilities and fitness, thus proving its evolutionary role in contemporary populations.

scholarly journals Schizophrenia risk and reproductive success: a Mendelian randomization study

2019 ◽  
Vol 6 (3) ◽  
pp. 181049 ◽  
Author(s):  
Rebecca B. Lawn ◽  
Hannah M. Sallis ◽  
Amy E. Taylor ◽  
Robyn E. Wootton ◽  
George Davey Smith ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Mendelian Randomization ◽  
Causal Effect ◽  
Sexual Partners ◽  
Age At First Birth ◽  
First Birth ◽  
Genetic Liability ◽  
Number Of Children ◽  
Fitness Advantage ◽  
Number Of Sexual Partners

Schizophrenia is a debilitating and heritable mental disorder associated with lower reproductive success. However, the prevalence of schizophrenia is stable over populations and time, resulting in an evolutionary puzzle: how is schizophrenia maintained in the population, given its apparent fitness costs? One possibility is that increased genetic liability for schizophrenia, in the absence of the disorder itself, may confer some reproductive advantage. We assessed the correlation and causal effect of genetic liability for schizophrenia with number of children, age at first birth and number of sexual partners using data from the Psychiatric Genomics Consortium and UK Biobank. Linkage disequilibrium score regression showed little evidence of genetic correlation between genetic liability for schizophrenia and number of children ( r g = 0.002, p = 0.84), age at first birth ( r g = −0.007, p = 0.45) or number of sexual partners ( r g = 0.007, p = 0.42). Mendelian randomization indicated no robust evidence of a causal effect of genetic liability for schizophrenia on number of children (mean difference: 0.003 increase in number of children per doubling in the natural log odds ratio of schizophrenia risk, 95% confidence interval (CI): −0.003 to 0.009, p = 0.39) or age at first birth (−0.004 years lower age at first birth, 95% CI: −0.043 to 0.034, p = 0.82). We find some evidence of a positive effect of genetic liability for schizophrenia on number of sexual partners (0.165 increase in the number of sexual partners, 95% CI: 0.117–0.212, p = 5.30×10 −10 ). These results suggest that increased genetic liability for schizophrenia does not confer a fitness advantage but does increase mating success.

scholarly journals European countries with delayed childbearing are not those with lower fertility

Genus ◽  
2021 ◽  
Vol 77 (1) ◽  
Author(s):  
Éva Beaujouan ◽  
Laurent Toulemon
Keyword(s):  
Context Effects ◽  
Negative Relationship ◽  
Age At First Birth ◽  
First Birth ◽  
Individual Level ◽  
Number Of Children ◽  
Country Level ◽  
Strong Negative Relationship ◽  
Lower Fertility ◽  
The Individual

AbstractAt the individual level, a very strong negative relationship is observed between age at first birth and total number of children. However, at the country level, it is possible that no relationship exists between factors that reduce fertility at younger ages and stimulate it at older ages. Hence, across countries, the size of the decline in youth fertility is potentially unrelated to the size of the increase in fertility at older ages or the decline in total fertility. We study the fertility of women and their age at childbirth, with particular attention to their evolution over the last 40 years in countries across Europe. Comparing these countries, the increase in births after age 30 has occurred relatively independently of the decline at younger ages according to both period and cohort, and we find no positive relationship between the delay of first birth and decline in total fertility. On the contrary, an inverse relationship evidently exists at the country level, as longer delays generally correspond to smaller declines in total fertility. Context effects largely dominate individual constraints and play an important role in the occurrence of later births.

scholarly journals Schizophrenia risk and reproductive success: A Mendelian randomization study

2018 ◽  
Author(s):  
Rebecca B Lawn ◽  
Hannah M Sallis ◽  
Amy E Taylor ◽  
Robyn E Wootton ◽  
George Davey Smith ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Mendelian Randomization ◽  
Causal Effect ◽  
Age At First Birth ◽  
First Birth ◽  
Genetic Liability ◽  
Number Of Children ◽  
Log Odds ◽  
Using Data ◽  
Robust Evidence

SummarySchizophrenia is a debilitating and heritable mental disorder associated with lower reproductive success. However, the prevalence of schizophrenia is stable over populations and time, resulting in an evolutionary puzzle: how is schizophrenia maintained in the population given its apparent fitness costs? One possibility is that increased genetic liability for schizophrenia, in the absence of the disorder itself, may confer some reproductive advantage. We assessed the correlation and causal effect of genetic liability for schizophrenia with number of children and age at first birth using data from the Psychiatric Genomics Consortium and UK Biobank. Linkage disequilibrium score regression showed little evidence of genetic correlation between genetic liability for schizophrenia and number of children (rg=0.002, p=0.84) or age at first birth (rg=-0.007, p=0.45). Mendelian randomization indicated no robust evidence of a causal effect of genetic liability for schizophrenia on number of children (mean difference: 0.003 increase in number of children per doubling in the natural log odds ratio of schizophrenia risk, 95% CI: −0.003 to 0.009, p=0.39) or age at first birth (−0.004 years lower age at first birth, 95% CI: −0.043 to 0.034, p=0.82). These results suggest that increased genetic liability for schizophrenia does not confer a reproductive advantage.

scholarly journals Variations in reproductive events across life: a pooled analysis of data from 505 147 women across 10 countries

2019 ◽  
Vol 34 (5) ◽  
pp. 881-893 ◽  
Author(s):  
Keyword(s):  
Age At Menarche ◽  
Age At First Birth ◽  
First Birth ◽  
Natural Menopause ◽  
Individual Level ◽  
Level Data ◽  
Education Levels ◽  
Reproductive Events ◽  
Racial Ethnic ◽  
Reproductive Indices

Abstract STUDY QUESTION How has the timing of women’s reproductive events (including ages at menarche, first birth, and natural menopause, and the number of children) changed across birth years, racial/ethnic groups and educational levels? SUMMARY ANSWER Women who were born in recent generations (1970–84 vs before 1930) or those who with higher education levels had menarche a year earlier, experienced a higher prevalence of nulliparity and had their first child at a later age. WHAT IS KNOWN ALREADY The timing of key reproductive events, such as menarche and menopause, is not only indicative of current health status but is linked to the risk of adverse hormone-related health outcomes in later life. Variations of reproductive indices across different birth years, race/ethnicity and socioeconomic positions have not been described comprehensively. STUDY DESIGN, SIZE, DURATION Individual-level data from 23 observational studies that contributed to the International Collaboration for a Life Course Approach to Reproductive Health and Chronic Disease Events (InterLACE) consortium were included. PARTICIPANTS/MATERIALS, SETTING, METHODS Altogether 505 147 women were included. Overall estimates for reproductive indices were obtained using a two-stage process: individual-level data from each study were analysed separately using generalised linear models. These estimates were then combined using random-effects meta-analyses. MAIN RESULTS AND THE ROLE OF CHANCE Mean ages were 12.9 years at menarche, 25.7 years at first birth, and 50.5 years at natural menopause, with significant between-study heterogeneity (I2 > 99%). A linear trend was observed across birth year for mean age at menarche, with women born from 1970 to 1984 having menarche one year earlier (12.6 years) than women born before 1930 (13.5 years) (P for trend = 0.0014). The prevalence of nulliparity rose progressively from 14% of women born from 1940–49 to 22% of women born 1970–84 (P = 0.003); similarly, the mean age at first birth rose from 24.8 to 27.3 years (P = 0.0016). Women with higher education levels had fewer children, later first birth, and later menopause than women with lower education levels. After adjusting for birth year and education level, substantial variation was present for all reproductive events across racial/ethnic/regional groups (all P values < 0.005). LIMITATIONS, REASONS FOR CAUTION Variations of study design, data collection methods, and sample selection across studies, as well as retrospectively reported age at menarche, age at first birth may cause some bias. WIDER IMPLICATIONS OF THE FINDINGS This global consortium study found robust evidence on variations in reproductive indices for women born in the 20th century that appear to have both biological and social origins. STUDY FUNDING/COMPETING INTEREST(S) InterLACE project is funded by the Australian National Health and Medical Research Council project grant (APP1027196). GDM is supported by the Australian National Health and Medical Research Council Principal Research Fellowship (APP1121844).

scholarly journals Does natural selection favour taller stature among the tallest people on earth?

2015 ◽  
Vol 282 (1806) ◽  
pp. 20150211 ◽  
Author(s):  
Gert Stulp ◽  
Louise Barrett ◽  
Felix C. Tropf ◽  
Melinda Mills
Keyword(s):  
Natural Selection ◽  
Reproductive Success ◽  
The Netherlands ◽  
Child Survival ◽  
Average Height ◽  
Tall Stature ◽  
Age At First Birth ◽  
Number Of Children ◽  
The North ◽  
Rate Of Increase

The Dutch are the tallest people on earth. Over the last 200 years, they have grown 20 cm in height: a rapid rate of increase that points to environmental causes. This secular trend in height is echoed across all Western populations, but came to an end, or at least levelled off, much earlier than in The Netherlands. One possibility, then, is that natural selection acted congruently with these environmentally induced changes to further promote tall stature among the people of the lowlands. Using data from the LifeLines study, which follows a large sample of the population of the north of The Netherlands ( n = 94 516), we examined how height was related to measures of reproductive success (as a proxy for fitness). Across three decades (1935–1967), height was consistently related to reproductive output (number of children born and number of surviving children), favouring taller men and average height women. This was despite a later age at first birth for taller individuals. Furthermore, even in this low-mortality population, taller women experienced higher child survival, which contributed positively to their increased reproductive success. Thus, natural selection in addition to good environmental conditions may help explain why the Dutch are so tall.

scholarly journals Genome-wide analysis identifies genetic effects on reproductive success and ongoing natural selection at the FADS locus

2020 ◽  
Author(s):  
Iain Mathieson ◽  
Felix R. Day ◽  
Nicola Barban ◽  
Felix C. Tropf ◽  
David M. Brazel ◽  
...  
Keyword(s):  
Natural Selection ◽  
Reproductive Success ◽  
European Ancestry ◽  
Age At First Birth ◽  
Hormone Regulation ◽  
Number Of Children ◽  
Two Generations ◽  
Reproductive Ageing ◽  
Children Ever Born ◽  
Using Data

AbstractIdentifying genetic determinants of reproductive success may highlight mechanisms underlying fertility and also identify alleles under present-day selection. Using data in 785,604 individuals of European ancestry, we identify 43 genomic loci associated with either number of children ever born (NEB) or childlessness. These loci span diverse aspects of reproductive biology across the life course, including puberty timing, age at first birth, sex hormone regulation and age at menopause. Missense alleles in ARHGAP27 were associated with increased NEB but reduced reproductive lifespan, suggesting a trade-off between reproductive ageing and intensity. As NEB is one component of evolutionary fitness, our identified associations indicate loci under present-day natural selection. Accordingly, we find that NEB-increasing alleles have increased in frequency over the past two generations. Furthermore, integration with data from ancient selection scans identifies a unique example of an allele—FADS1/2 gene locus—that has been under selection for thousands of years and remains under selection today. Collectively, our findings demonstrate that diverse biological mechanisms contribute to reproductive success, implicating both neuro-endocrine and behavioural influences.

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