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Ukonaho S, Chapman SN, Briga M, Lummaa V. Grandmother presence improved grandchild survival against childhood infections but not vaccination coverage in historical Finns. Proc Biol Sci 2023; 290:20230690. [PMID: 37253424 PMCID: PMC10229226 DOI: 10.1098/rspb.2023.0690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 05/02/2023] [Indexed: 06/01/2023] Open
Abstract
Grandmother presence can improve the number and survival of their grandchildren, but what grandmothers protect against and how they achieve it remains poorly known. Before modern medical care, infections were leading causes of childhood mortality, alleviated from the nineteenth century onwards by vaccinations, among other things. Here, we combine two individual-based datasets on the genealogy, cause-specific mortality and vaccination status of eighteenth- and nineteenth-century Finns to investigate two questions. First, we tested whether there were cause-specific benefits of grandmother presence on grandchild survival from highly lethal infections (smallpox, measles, pulmonary and diarrhoeal infections) and/or accidents. We show that grandmothers decreased all-cause mortality, an effect which was mediated through smallpox, pulmonary and diarrhoeal infections, but not via measles or accidents. Second, since grandmothers have been suggested to increase vaccination coverage, we tested whether the grandmother effect on smallpox survival was mediated through increased or earlier vaccination, but we found no evidence for such effects. Our findings that the beneficial effects of grandmothers are in part driven by increased survival from some (but not all) childhood infections, and are not mediated via vaccination, have implications for public health, societal development and human life-history evolution.
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Affiliation(s)
- Susanna Ukonaho
- Department of Biology, University of Turku, 20014 Turku, Finland
| | - Simon N. Chapman
- INVEST Flagship Research Centre, University of Turku, 20014 Turku, Finland
| | - Michael Briga
- Department of Biology, University of Turku, 20014 Turku, Finland
- Infectious Disease Epidemiology Group, Max Planck Institute for Infection Biology, 10117 Berlin, Germany
| | - Virpi Lummaa
- Department of Biology, University of Turku, 20014 Turku, Finland
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Young EA, Chesterton E, Lummaa V, Postma E, Dugdale HL. The long-lasting legacy of reproduction: lifetime reproductive success shapes expected genetic contributions of humans after 10 generations. Proc Biol Sci 2023; 290:20230287. [PMID: 37161329 PMCID: PMC10170207 DOI: 10.1098/rspb.2023.0287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Abstract
An individual's lifetime reproductive success (LRS) measures its realized genetic contributions to the next generation, but how well does it predict this over longer periods? Here we use human genealogical data to estimate expected individual genetic contributions (IGC) and quantify the degree to which LRS, relative to other fitness proxies, predicts IGC over longer periods. This allows an identification of the life-history stages that are most important in shaping variation in IGC. We use historical genealogical data from two non-isolated local populations in Switzerland to estimate the stabilized IGC for 2230 individuals approximately 10 generations after they were born. We find that LRS explains 30% less variation in IGC than the best predictor of IGC, the number of grandoffspring. However, albeit less precise than the number of grandoffspring, we show that LRS does provide an unbiased prediction of IGC. Furthermore, it predicts IGC better than lifespan, and accounting for offspring survival to adulthood does not improve the explanatory power. Overall, our findings demonstrate the value of human genealogical data to evolutionary biology and suggest that reproduction-more than lifespan or offspring survival-impacts the long-term genetic contributions of historic humans, even in a population with appreciable migration.
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Affiliation(s)
- Euan A Young
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, 9747AG, The Netherlands
| | - Ellie Chesterton
- Faculty of Biological Sciences, School of Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Virpi Lummaa
- Department of Biology, University of Turku, Turku 20014, Finland
| | - Erik Postma
- Centre for Ecology and Conservation, University of Exeter, Penryn TR10 9FE, UK
| | - Hannah L Dugdale
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, 9747AG, The Netherlands
- Faculty of Biological Sciences, School of Biology, University of Leeds, Leeds LS2 9JT, UK
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Briga M, Griffin RM, Berger V, Pettay JE, Lummaa V. What have humans done for evolutionary biology? Contributions from genes to populations. Proc Biol Sci 2018; 284:rspb.2017.1164. [PMID: 29118130 DOI: 10.1098/rspb.2017.1164] [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: 05/25/2017] [Accepted: 10/09/2017] [Indexed: 12/15/2022] Open
Abstract
Many fundamental concepts in evolutionary biology were discovered using non-human study systems. Humans are poorly suited to key study designs used to advance this field, and are subject to cultural, technological, and medical influences often considered to restrict the pertinence of human studies to other species and general contexts. Whether studies using current and recent human populations provide insights that have broader biological relevance in evolutionary biology is, therefore, frequently questioned. We first surveyed researchers in evolutionary biology and related fields on their opinions regarding whether studies on contemporary humans can advance evolutionary biology. Almost all 442 participants agreed that humans still evolve, but fewer agreed that this occurs through natural selection. Most agreed that human studies made valuable contributions to evolutionary biology, although those less exposed to human studies expressed more negative views. With a series of examples, we discuss strengths and limitations of evolutionary studies on contemporary humans. These show that human studies provide fundamental insights into evolutionary processes, improve understanding of the biology of many other species, and will make valuable contributions to evolutionary biology in the future.
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Affiliation(s)
- Michael Briga
- Department of Biology, University of Turku, Turku 20014, Finland
| | - Robert M Griffin
- Department of Biology, University of Turku, Turku 20014, Finland
| | - Vérane Berger
- Department of Biology, University of Turku, Turku 20014, Finland
| | - Jenni E Pettay
- Department of Biology, University of Turku, Turku 20014, Finland
| | - Virpi Lummaa
- Department of Biology, University of Turku, Turku 20014, Finland
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Hamel S, Gaillard JM, Yoccoz NG, Bassar RD, Bouwhuis S, Caswell H, Douhard M, Gangloff EJ, Gimenez O, Lee PC, Smallegange IM, Steiner UK, Vedder O, Vindenes Y. General conclusion to the special issue Moving forward on individual heterogeneity. OIKOS 2018. [DOI: 10.1111/oik.05223] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Sandra Hamel
- Dept of Arctic and Marine Biology; UiT The Arctic Univ. of Norway; Tromsø Norway
| | | | - Nigel G. Yoccoz
- Dept of Arctic and Marine Biology; UiT The Arctic Univ. of Norway; Tromsø Norway
| | - Ron D. Bassar
- Dept of Biology; Williams College; Williamstown MA USA
| | - Sandra Bouwhuis
- Inst of Avian Research ‘Vogelwarte Helgoland’; Wilhelmshaven Germany
| | - Hal Caswell
- Inst. for Biodiversity and Ecosystem Dynamics; Univ. of Amsterdam; Amsterdam the Netherlands
| | | | - Eric J. Gangloff
- Station d’Ecologie Théorique et Expérimentale du CNRS; Moulis France
| | - Olivier Gimenez
- CEFE UMR 5175; CNRS, Univ. de Montpellier, Univ. Paul-Valéry Montpellier; Montpellier France
| | - Phylis C. Lee
- Psychology, Faculty of Natural Sciences; Univ. of Stirling; Stirling UK
| | - Isabel M. Smallegange
- Inst. for Biodiversity and Ecosystem Dynamics; Univ. of Amsterdam; Amsterdam the Netherlands
| | - Ulrich K. Steiner
- Max-Planck Odense Centre on the Biodemography of Aging, and Dept of Biology; Odense Denmark
| | - Oscar Vedder
- Inst of Avian Research ‘Vogelwarte Helgoland’; Wilhelmshaven Germany
- Groningen Inst. for Evolutionary Life Sciences; Univ. of Groningen; Groningen the Netherlands
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Brosnan SF, Postma E. Humans as a model for understanding biological fundamentals. Proc Biol Sci 2017; 284:rspb.2017.2146. [PMID: 29237858 DOI: 10.1098/rspb.2017.2146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 10/30/2017] [Indexed: 12/15/2022] Open
Abstract
How special are humans? This question drives scholarly output across both the sciences and the humanities. Whereas some disciplines, and the humanities in particular, aim at gaining a better understanding of humans per se, most biologists ultimately aim to understand life in general. This raises the question of whether and when humans are acceptable, or even desirable, models of biological fundamentals. Especially for basic biological processes, non-human species are generally accepted as a relevant model to study topics for which studying humans is impractical, impossible, or ethically inadvisable, but the reverse is controversial: are humans 'too unique' to be informative with respect to biological fundamentals relevant to other species? Or are there areas where we share key components, or for which our very uniqueness serves to allow novel explorations? In this special feature, authors from disciplines including biology, psychology, anthropology, neuroscience and philosophy tackle this question. Their overall conclusion is a qualified yes: humans do tell us about biological fundamentals, in some contexts. We hope this special feature will spur a discussion that will lead to a more careful delineation of the similarities and the differences between humans and other species, and how these impact the study of biological fundamentals.
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Affiliation(s)
- Sarah F Brosnan
- Departments of Psychology, Philosophy and Neuroscience, Center for Behavioral Neuroscience, Language Research Center, Georgia State University, Atlanta, GA, USA
| | - Erik Postma
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Penryn TR10 9FE, UK
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Abstract
Like every other species, our species is the result of descent with modification under the influence of natural selection; a tip in an increasingly large and deep series of nested clades, as we trace its ancestry back to increasingly remote antecedents. As a consequence of shared history, our species has much in common with many others; as a consequence of its production by the general mechanisms of evolution, our species carries information about the mechanisms that shaped other species as well. For reasons unconnected to biological theory, we have far more information about humans than we do about other species. So in principle and in practice, humans should be usable as model organisms, and no one denies the truth of this for mundane physical traits, though harnessing human data for more general questions proves to be quite challenging. However, it is also true that human cognitive and behavioural characteristics, and human social groups, are apparently radically unlike those of other animals. Humans are exceptional products of evolution and perhaps that makes them an unsuitable model system for those interested in the evolution of cooperation, complex cognition, group formation, family structure, communication, cultural learning and the like. In all these respects, we are complex and extreme cases, perhaps shaped by mechanisms (like cultural evolution or group selection) that play little role in other lineages. Most of the papers in this special issue respond by rejecting or downplaying exceptionalism. I argue that it can be an advantage: understanding the human exception reveals constraints that have restricted evolutionary options in many lineages.
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Affiliation(s)
- Kim Sterelny
- Philosophy, Australian National University, Canberra, Australian Capital Territory 0200, Australia
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Griffin RM, Hayward AD, Bolund E, Maklakov AA, Lummaa V. Sex differences in adult mortality rate mediated by early-life environmental conditions. Ecol Lett 2017; 21:235-242. [PMID: 29210148 DOI: 10.1111/ele.12888] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 09/18/2017] [Accepted: 11/06/2017] [Indexed: 12/16/2022]
Abstract
Variation in sex differences is affected by both genetic and environmental variation, with rapid change in sex differences being more likely due to environmental change. One case of rapid change in sex differences is human lifespan, which has become increasingly female-biased in recent centuries. Long-term consequences of variation in the early-life environment may, in part, explain such variation in sex differences, but whether the early-life environment mediates sex differences in life-history traits is poorly understood in animals. Combining longitudinal data on 60 cohorts of pre-industrial Finns with environmental data, we show that the early-life environment is associated with sex differences in adult mortality and expected lifespan. Specifically, low infant survival rates and high rye yields (an important food source) in early-life are associated with female-bias in adult lifespan. These results support the hypothesis that environmental change has the potential to affect sex differences in life-history traits in natural populations of long-lived mammals.
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Affiliation(s)
- Robert M Griffin
- Department of Biology, University of Turku, 20014, Turku, Finland
| | - Adam D Hayward
- Department of Biological and Environmental Sciences, University of Stirling, Stirling, FK9 4LA, UK
| | - Elisabeth Bolund
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, 752 36, Sweden
| | - Alexei A Maklakov
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, 752 36, Sweden.,School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Virpi Lummaa
- Department of Biology, University of Turku, 20014, Turku, Finland
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