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Salinari G, De Santis G, Zarulli V, Giuliani C, Franceschi C, Breschi M. Fertility decline and the emergence of excess female survival in post-reproductive ages in Italy. GENUS 2022. [DOI: 10.1186/s41118-022-00166-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
AbstractIn Italy, at least in the cohorts born up to the beginning of the twentieth century, women’s mortality in post-reproductive ages was influenced by fertility, with large progenies (and, to a lesser extent, childlessness) leading to markedly lower survival chances. This relationship proved strong enough to affect the female-to-male ratio in old age as fertility declined. In this paper, we show that various measures of extra female survival at high ages are closely connected to the fertility transition in Italy, and to its peculiar historical and geographical evolution.
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Helle S. Selection bias in studies of human reproduction-longevity trade-offs. Proc Biol Sci 2018; 284:rspb.2017.2104. [PMID: 29187632 DOI: 10.1098/rspb.2017.2104] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 10/30/2017] [Indexed: 11/12/2022] Open
Abstract
A shorter lifespan as a potential cost of high reproductive effort in humans has intrigued researchers for more than a century. However, the results have been inconclusive so far and despite strong theoretical expectations we do not currently have compelling evidence for the longevity costs of reproduction. Using Monte Carlo simulation, it is shown here that a common practice in human reproduction-longevity studies using historical data (the most relevant data sources for this question), the omission of women who died prior to menopausal age from the analysis, results in severe underestimation of the potential underlying trade-off between reproduction and lifespan. In other words, assuming that such a trade-off is expressed also during reproductive years, the strength of the trade-off between reproduction and lifespan is progressively weakened when women dying during reproductive ages are sequentially and non-randomly excluded from the analysis. In cases of small sample sizes (e.g. few hundreds of observations), this selection bias by reducing statistical power may even partly explain the null results commonly found in this field. Future studies in this field should thus apply statistical approaches that account for or avoid selection bias in order to recover reliable effect size estimates between reproduction and longevity.
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Affiliation(s)
- Samuli Helle
- Section of Ecology, Department of Biology, University of Turku, Turku 20014, Finland
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van den Berg N, Beekman M, Smith KR, Janssens A, Slagboom PE. Historical demography and longevity genetics: Back to the future. Ageing Res Rev 2017; 38:28-39. [PMID: 28689042 DOI: 10.1016/j.arr.2017.06.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 06/30/2017] [Accepted: 06/30/2017] [Indexed: 11/30/2022]
Abstract
Research into the genetic component of human longevity can provide important insights in mechanisms that may protect against age-related diseases and multi-morbidity. Thus far only a limited number of robust longevity loci have been detected in either candidate or genome wide association studies. One of the issues in these genetic studies is the definition of the trait being either lifespan, including any age at death or longevity, i.e. survival above a diverse series of thresholds. Likewise heritability and segregation research have conflated lifespan with longevity. The heritability of lifespan estimated across most studies has been rather low. Environmental factors have not been sufficiently investigated and the total amount of genetic variance contributing to longevity has not been estimated in sufficiently well-defined and powered studies. Up to now, genetic longevity studies lack the required insights into the nature and size of the genetic component and the optimal strategies for meta-analysis and subject selection for Next Generation Sequencing efforts. Historical demographic data containing deep genealogical information may help in estimating the best definition and heritability for longevity, its transmission patterns in multi-generational datasets and may allow relevant additive and modifying environmental factors such as socio-economic status, geographical background, exposure to environmental effects, birth order, and number of children to be included. In this light historical demographic data may be very useful for identifying lineages in human populations that are worth investigating further by geneticists.
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Affiliation(s)
- Niels van den Berg
- Department of Molecular Epidemiology, Leiden University, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
| | - Marian Beekman
- Department of Molecular Epidemiology, Leiden University, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
| | - Ken Robert Smith
- Department of Family and Consumer Studies, Population Sciences, Huntsman Cancer Institute, University of Utah, 225 S. 1400 E. Rm 228, Salt Lake City, United States.
| | - Angelique Janssens
- Department of Economic, Social, and Demographic History, Radboud University, Erasmusplein 1, 6525 HT Nijmegen, The Netherlands.
| | - Pieternella Eline Slagboom
- Department of Molecular Epidemiology, Leiden University, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
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Gavrus-Ion A, Sjøvold T, Hernández M, González-José R, Esteban Torné ME, Martínez-Abadías N, Esparza M. Measuring fitness heritability: Life history traits versus morphological traits in humans. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2017. [DOI: 10.1002/ajpa.23271] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Alina Gavrus-Ion
- Section of Zoology and Biological Anthropology; University of Barcelona; Barcelona Spain
| | | | - Miguel Hernández
- Section of Zoology and Biological Anthropology; University of Barcelona; Barcelona Spain
| | - Rolando González-José
- Instituto Patagónico de Ciencias Sociales y Humanas, Centro Nacional Patagónico, Consejo Nacional de Investigaciones Científicas y Técnicas; Puerto Madryn Argentina
| | - María Esther Esteban Torné
- Section of Zoology and Biological Anthropology; University of Barcelona; Barcelona Spain
- Institut de Recerca de la Biodiversitat (IRBIO), University of Barcelona; Barcelona Spain
| | - Neus Martínez-Abadías
- Section of Zoology and Biological Anthropology; University of Barcelona; Barcelona Spain
- Centre for Genomic Regulation (CRG); Barcelona Spain
- Universitat Pompeu Fabra; Barcelona Spain
| | - Mireia Esparza
- Section of Zoology and Biological Anthropology; University of Barcelona; Barcelona Spain
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Poulain M, Herm A, Chambre D, Pes G. Fertility History, Children's Gender, and Post-Reproductive Survival in a Longevous Population. BIODEMOGRAPHY AND SOCIAL BIOLOGY 2016; 62:262-274. [PMID: 27809663 DOI: 10.1080/19485565.2016.1207502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The question of whether mothers' fertility history influences their post-reproductive survival has been addressed frequently in the scientific literature. Using data from Villagrande Strisaili, Sardinia, where longevity is higher than anywhere else in Europe, we analyzed the relationship between the fertility pattern of mothers who survived past age 50 (n = 539) and their post-reproductive lifespan. We find that, after adjustment for potential confounders (mothers' birth cohort, survival of spouse), the mothers who on average delivered their children later displayed a reduced mortality risk (‒2.9 percent for each additional year), supporting previously reported findings. We also find that a male-skewed offspring ratio was associated with decreased mortality risk of mothers, with longer survival of mothers who delivered their sons above age 35 (p = 0.005), a result not found for daughters. So far, no biological explanation has been suggested for the positive effect of delivering sons later in life. We conjecture that in our dataset stronger nonbiological factors such as gender-specific sociocultural and economic factors may have masked the negative effect reported in other populations, for which a biological explanation was proposed.
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Affiliation(s)
- Michel Poulain
- a Estonian Institute for Population Studies , Tallinn University , Tallinn , Estonia
- b Institute for the Analysis of Change in Historical and Contemporary Societies (IACCHOS) , Université Catholique de Louvain , Louvain-la-Neuve , Belgium
| | - Anne Herm
- a Estonian Institute for Population Studies , Tallinn University , Tallinn , Estonia
| | | | - Gianni Pes
- d Department of Clinical and Experimental Medicine , Università degli Studi di Sassari , Sassari , Italy
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6
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Natural fertility and longevity. Fertil Steril 2015; 103:1109-16. [PMID: 25934597 DOI: 10.1016/j.fertnstert.2015.03.030] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 03/23/2015] [Accepted: 03/25/2015] [Indexed: 12/25/2022]
Abstract
Much empirical work suggests an association between fertility patterns and longevity. I review this association, focusing on natural fertility populations and emphasizing the role of both the timing and the intensity of fertility. Overall, it appears that although age at last reproduction routinely correlates with post-reproductive longevity, suggesting a slower rate of senescence among late fertile women, the same is not true for age at first reproduction and parity. I discuss some of the conceptual and methodologic issues, as well as the sources of the biases, that have been a persistent feature of this body of research. I conclude by suggesting avenues of research that could be initiated or pursued in the area.
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Wang X, Byars SG, Stearns SC. Genetic links between post-reproductive lifespan and family size in Framingham. Evol Med Public Health 2013; 2013:241-53. [PMID: 24481203 PMCID: PMC3868361 DOI: 10.1093/emph/eot013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 06/17/2013] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND AND OBJECTIVES Is there a trade-off between children ever born (CEB) and post-reproductive lifespan in humans? Here, we report a comprehensive analysis of reproductive trade-offs in the Framingham Heart Study (FHS) dataset using phenotypic and genotypic correlations and a genome-wide association study (GWAS) to look for single-nucleotide polymorphisms (SNPs) that are related to the association between CEB and lifespan. METHODOLOGY We calculated the phenotypic and genetic correlations of lifespan with CEB for men and women in the Framingham dataset, and then performed a GWAS to search for SNPs that might affect the relationship between post-reproductive lifespan and CEB. RESULTS We found significant negative phenotypic correlations between CEB and lifespan in both women (rP = -0.133, P < 0.001) and men (rP = -0. 079, P = 0.036). The genetic correlation was large, highly significant and strongly negative in women (rG = -0.877, P = 0.009) in a model without covariates, but not in men (P = 0.777). The GWAS identified five SNPs associated with the relationship between CEB and post-reproductive lifespan in women; some are near genes that have been linked to cancer. None were identified in men. CONCLUSIONS AND IMPLICATIONS We identified several SNPs for which the relationship between CEB and post-reproductive lifespan differs by genotype in women in the FHS who were born between 1889 and 1958. That result was not robust to changes in the sample. Further studies on larger samples are needed to validate the antagonistic pleiotropy of these genes.
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Affiliation(s)
- Xiaofei Wang
- Department of Statistics, Yale University, New Haven, CT 06520-8102, USA, Department of Biology, Copenhagen University, Universitetsparken 15, 2100 Copenhagen, Denmark and Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520-8102, USA
| | - Sean G. Byars
- Department of Statistics, Yale University, New Haven, CT 06520-8102, USA, Department of Biology, Copenhagen University, Universitetsparken 15, 2100 Copenhagen, Denmark and Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520-8102, USA
| | - Stephen C. Stearns
- Department of Statistics, Yale University, New Haven, CT 06520-8102, USA, Department of Biology, Copenhagen University, Universitetsparken 15, 2100 Copenhagen, Denmark and Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520-8102, USA
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Chereji E, Gatz M, Pedersen NL, Prescott CA. Reexamining the association between fertility and longevity: testing the disposable soma theory in a modern human sample of twins. J Gerontol A Biol Sci Med Sci 2012; 68:499-509. [PMID: 23213027 DOI: 10.1093/gerona/gls218] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The disposable soma theory proposes a trade-off between fertility and longevity but existing findings on this association have been mixed. This study used data from 15,622 twins born between 1901 and 1925 ascertained from the population-based Swedish Twin Registry to test the child-longevity association and whether it is accounted for by individual-level factors or by genetic and environmental factors shared by family members. Based on survival analysis, both women and men with children had significantly longer survival relative to the childless, with a slightly higher relative advantage in men. Adjustments for demographic factors and cotwin fertility did not mediate the parenting-survival association, indicating that this association is attributable to individual-level factors associated with fertility rather than family-level environmental or genetic factors shared by cotwins. These results, derived from a large, population-based sample, are inconsistent with the disposable soma theory as applied to modern human populations.
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Affiliation(s)
- Elizabeth Chereji
- Department of Psychology, University of Southern California, Los Angeles, CA 90089-1061, USA.
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Gagnon A, Smith KR, Tremblay M, Vézina H, Paré PP, Desjardins B. Is there a trade-off between fertility and longevity? A comparative study of women from three large historical databases accounting for mortality selection. Am J Hum Biol 2009; 21:533-40. [PMID: 19298004 PMCID: PMC6121733 DOI: 10.1002/ajhb.20893] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Frontier populations provide exceptional opportunities to test the hypothesis of a trade-off between fertility and longevity. In such populations, mechanisms favoring reproduction usually find fertile ground, and if these mechanisms reduce longevity, demographers should observe higher postreproductive mortality among highly fertile women. We test this hypothesis using complete female reproductive histories from three large demographic databases: the Registre de la population du Québec ancien (Université de Montréal), which covers the first centuries of settlement in Quebec; the BALSAC database (Université du Québec à Chicoutimi), including comprehensive records for the Saguenay-Lac-St-Jean (SLSJ) in Quebec in the nineteenth and twentieth centuries; and the Utah Population Database (University of Utah), including all individuals who experienced a vital event on the Mormon Trail and their descendants. Together, the three samples allow for comparisons over time and space, and represent one of the largest set of natural fertility cohorts used to simultaneously assess reproduction and longevity. Using survival analyses, we found a negative influence of parity and a positive influence of age at last child on postreproductive survival in the three populations, as well as a significant interaction between these two variables. The effect sizes of all these parameters were remarkably similar in the three samples. However, we found little evidence that early fertility affects postreproductive survival. The use of Heckman's procedure assessing the impact of mortality selection during reproductive ages did not appreciably alter these results. We conclude our empirical investigation by discussing the advantages of comparative approaches.
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Affiliation(s)
- Alain Gagnon
- Population Studies Centre, Department of Sociology, University of Western Ontario, London, Canada.
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Alter G, Dribe M, Van Poppel F. Widowhood, family size, and post-reproductive mortality: a comparative analysis of three populations in nineteenth-century Europe. Demography 2008; 44:785-806. [PMID: 18232211 DOI: 10.1353/dem.2007.0037] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Researchers from a number of disciplines have offered competing theories about the effects oJ childbearing on parents 'postreproductive longevity. The "disposable soma theory" argues that investments in somatic maintenance increase longevity but reduce childbearing. "Maternal depletion" models suggest that the rigors of childrearing increase mortality in later years. Other researchers consider continued childbearing a sign of healthy aging and a predictor of future longevity. Empirical studies have produced inconsistent and contradictory results. Our focus is on the experience of widowhood, which has been ignored in previous studies. We hypothesize that the death of a spouse is a stressful event with long-term consequences for health, especially for women with small children. Data are drawn from historical sources in Sweden, Belgium, and the Netherlands from 1766 to 1980. Postreproductive mortality was highest among young widows with larger families in all three samples. Age at last birth had little or no effect. We conclude that raising children under adverse circumstances can have long-lasting, harmful effects on a mother's health.
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Affiliation(s)
- George Alter
- Inter-university Consortium for Political and Social Research and Population Studies Center, University of Michigan, P.O. Box 1248, Ann Arbor, MI 48106-1248, USA.
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Helle S, Helama S. Climatic variability and the population dynamics of historical hunter-gatherers: the case of Sami of Northern Finland. Am J Hum Biol 2008; 19:844-53. [PMID: 17696129 DOI: 10.1002/ajhb.20650] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Our current knowledge on climate-mediated effects on human population dynamics is based on preindustrial agrarian societies where climate-induced crop failures had a major impact on fertility and mortality rates. However, because most of the human evolutionary history has been shaped by hunter-gatherer lifestyle relying on diverse plant and animal food sources, it is also important to understand how climate affected the population dynamics of hunter-gatherers. We thus studied whether climate, measured as a reconstructed annual mean temperature, had concurrent or delayed effects on the key components of population dynamics, annual births and deaths, in three historical (1722-1850) Sami populations of Northern Finland that depended mainly on fishing, hunting, and reindeer herding for their livelihood. We found only weak concurrent effects of mean temperature on annual births and deaths, although in general warm years correlated with increased birth and reduced mortality rates. Likewise, temperature-mediated delayed effects were mainly absent: in one population only, a warm previous year tended to reduce the number of births. By contrast, annual numbers of births and deaths were more closely associated, as indicated by negative correlations between births and deaths up to three previous years. To summarize, in contrast to historical agrarian societies, the population dynamics of historical Sami seemed to be only weakly associated with annual mean temperature, which may indicate that these populations, probably due to their dietary breadth, were rather unaffected by climatic variation.
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Affiliation(s)
- Samuli Helle
- Section of Ecology, Department of Biology, University of Turku, FI-20014 Turku, Finland.
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12
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Abstract
It is often assumed that Afrikaners stem from a small number of Dutch immigrants. As a result they should be genetically homogeneous, show founder effects and be rather inbred. By disentangling my own South African pedigree, that is on average 12 generations deep, I try to quantify the genetic heritage of an Afrikaner. As much as 6% of my genes have been contributed by slaves from Africa, Madagascar and India, and a woman from China. This figure compares well to other genetic and genealogical estimates. Seventy three percent of my lineages coalesce into common founders, and I am related in excess of 10 times to 20 founder ancestors (30 times to Willem Schalk van der Merwe). Significant founder effects are thus possible. The overrepresentation of certain founder ancestors is in part explained by the fact that they had more children. This is remarkable given that they lived more than 300 years (or 12 generations) ago. DECONSTRUCT, a new program for pedigree analysis, identified 125 common ancestors in my pedigree. However, these common ancestors are so distant from myself, paths of between 16 and 25 steps in length, that my inbreeding coefficient is not unusually high (f approximately 0.0019).
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Affiliation(s)
- J M Greeff
- Department of Genetics, University of Pretoria, Pretoria 0002, South Africa.
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Van Bodegom D, May L, Meij HJ, Westendorp RGJ. Regulation of Human Life Histories: The Role of the Inflammatory Host Response. Ann N Y Acad Sci 2007; 1100:84-97. [PMID: 17460167 DOI: 10.1196/annals.1395.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Most species with a long life span have few offspring while species with a short life span have many offspring. This evolutionary trade-off between fertility and body maintenance, based on the theory of r/K-selection, is a central theme in the theory of life history regulation. This trade-off is not only found between various species but also between individuals within one species. There is accumulating evidence for this trade-off in humans. We hypothesize that the innate immune system is a critical factor skewing an individual into the direction of either a high fertility or better maintenance strategy. As over thousands of years human survival has been highly dependent on resistance to infectious diseases, genetic adaptations resulting in inflammatory responses were favored. An inflammatory host response is critical to fight infection necessary to survive up to reproductive age. An inflammatory host response is also negatively associated with fertility and can explain for the trade-off between fertility and body maintenance. After human reproductive age, these inflammatory responses contribute also to development of chronic degenerative diseases. These will especially become apparent in affluent societies where the majority of individuals reach old age. Identifying the inflammatory host response as a critical factor both in the regulation of human life histories and in the occurrence of chronic diseases at old age implies means for intervention allowing individuals to live healthier for longer.
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Affiliation(s)
- David Van Bodegom
- Department of Geriatrics and Gerontology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
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Miller GF, Penke L. The evolution of human intelligence and the coefficient of additive genetic variance in human brain size. INTELLIGENCE 2007. [DOI: 10.1016/j.intell.2006.08.008] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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McArdle PF, Pollin TI, O'Connell JR, Sorkin JD, Agarwala R, Schäffer AA, Streeten EA, King TM, Shuldiner AR, Mitchell BD. Does having children extend life span? A genealogical study of parity and longevity in the Amish. J Gerontol A Biol Sci Med Sci 2006; 61:190-5. [PMID: 16510865 DOI: 10.1093/gerona/61.2.190] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The relationship between parity and life span is uncertain, with evidence of both positive and negative relationships being reported previously. We evaluated this issue by using genealogical data from an Old Order Amish community in Lancaster, Pennsylvania, a population characterized by large nuclear families, homogeneous lifestyle, and extensive genealogical records. METHODS The analysis was restricted to the set of 2,015 individuals who had children, were born between 1749 and 1912, and survived until at least age 50 years. Pedigree structures and birth and death dates were extracted from Amish genealogies, and the relationship between parity and longevity was examined using a variance component framework. RESULTS Life span of fathers increased in linear fashion with increasing number of children (0.23 years per additional child; p =.01), while life span of mothers increased linearly up to 14 children (0.32 years per additional child; p =.004) but decreased with each additional child beyond 14 (p =.0004). Among women, but not men, a later age at last birth was associated with longer life span (p =.001). Adjusting for age at last birth obliterated the correlation between maternal life span and number of children, except among mothers with ultrahigh (>14 children) parity. CONCLUSIONS We conclude that high parity among men and later menopause among women may be markers for increased life span. Understanding the biological and/or social factors mediating these relationships may provide insights into mechanisms underlying successful aging.
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Affiliation(s)
- Patrick F McArdle
- Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Helle S, Lummaa V, Jokela J. Are reproductive and somatic senescence coupled in humans? Late, but not early, reproduction correlated with longevity in historical Sami women. Proc Biol Sci 2005; 272:29-37. [PMID: 15875567 PMCID: PMC1634941 DOI: 10.1098/rspb.2004.2944] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Evolutionary theory of senescence emphasizes the importance of intense selection on early reproduction owing to the declining force of natural selection with age that constrains lifespan. In humans, recent studies have, however, suggested that late-life mortality might be more closely related to late rather than early reproduction, although the role of late reproduction on fitness remains unclear. We examined the association between early and late reproduction with longevity in historical post-reproductive Sami women. We also estimated the strength of natural selection on early and late reproduction using path analysis, and the effect of reproductive timing on offspring survival to adulthood and maternal risk of dying at childbirth. We found that natural selection favoured both earlier start and later cessation of reproduction, and higher total fecundity. Maternal age at childbirth was not related to offspring or maternal survival. Interestingly, females who produced their last offspring at advanced age also lived longest, while age at first reproduction and total fecundity were unrelated to female longevity. Our results thus suggest that reproductive and somatic senescence may have been coupled in these human populations, and that selection could have favoured late reproduction. We discuss alternative hypotheses for the mechanisms which might have promoted the association between late reproduction and longevity.
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Affiliation(s)
- Samuli Helle
- Section of Ecology, Department of Biology, University of Turku, FIN-20014 Turku, Finland.
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Pettay JE, Kruuk LEB, Jokela J, Lummaa V. Heritability and genetic constraints of life-history trait evolution in preindustrial humans. Proc Natl Acad Sci U S A 2005; 102:2838-43. [PMID: 15701704 PMCID: PMC549452 DOI: 10.1073/pnas.0406709102] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2004] [Indexed: 11/18/2022] Open
Abstract
An increasing number of studies have documented phenotypic selection on life-history traits in human populations, but less is known of the heritability and genetic constraints that mediate the response to selection on life-history traits in humans. We collected pedigree data for four generations of preindustrial (1745-1900) Finns who lived in premodern fertility and mortality conditions, and by using a restricted maximum-likelihood animal-model framework, we estimated the heritability of and genetic correlations between a suite of life-history traits and two alternative measures of fitness. First, we demonstrate high heritability of key life-history traits (fecundity, interbirth interval, age at last reproduction, and adult longevity) and measures of fitness (individual lambda and lifetime reproductive success) for females but not for males. This sex difference may have arisen because most of the measured traits are under physiological control of the female, such that a male's fitness in monogamous societies may depend mainly on the reproductive quality of his spouse. We found strong positive genetic correlations between female age at first reproduction and longevity, and between interbirth intervals and longevity, suggesting reduced life spans in females who either started to breed relatively early or who then bred frequently. Our results suggest that key female life-history traits in this premodern human population had high heritability and may have responded to natural selection. However genetic constraints between longevity and reproductive life-history traits may have constrained the evolution of life history and facilitated the maintenance of additive genetic variance in key life-history traits.
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Affiliation(s)
- Jenni E Pettay
- Section of Ecology, Department of Biology, University of Turku, FIN-20014, Turku, Finland.
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Helle S, Lummaa V, Jokela J. SELECTION FOR INCREASED BROOD SIZE IN HISTORICAL HUMAN POPULATIONS. Evolution 2004. [DOI: 10.1554/03-307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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