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Medawar and Hamilton on the selective forces in the evolution of ageing
Both Medawar and Hamilton contributed key ideas to the modern evolutionary theory of ageing. In particular, they both suggested that, in populations with overlapping generations, the force with which selection acts on traits declines with the age at which traits are expressed. This decline would eve...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Springer International Publishing
2021
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8616860/ https://www.ncbi.nlm.nih.gov/pubmed/34822012 http://dx.doi.org/10.1007/s40656-021-00476-6 |
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author | Giaimo, Stefano |
author_facet | Giaimo, Stefano |
author_sort | Giaimo, Stefano |
collection | PubMed |
description | Both Medawar and Hamilton contributed key ideas to the modern evolutionary theory of ageing. In particular, they both suggested that, in populations with overlapping generations, the force with which selection acts on traits declines with the age at which traits are expressed. This decline would eventually cause ageing to evolve. However, the biological literature diverges on the relationship between Medawar’s analysis of the force of selection and Hamilton’s. Some authors appear to believe that Hamilton perfected Medawar’s insightful, yet ultimately erroneous analysis of this force, while others see Hamilton’s analysis as a coherent development of, or the obvious complement to Medawar’s. Here, the relationship between the two analyses is revisited. Two things are argued for. First, most of Medawar’s alleged errors that Hamilton would had rectified seem not to be there. The origin of these perceived errors appears to be in a misinterpretation of Medawar’s writings. Second, the mathematics of Medawar and that of Hamilton show a significant overlap. However, different meanings are attached to the same mathematical expression. Medawar put forth an expression for the selective force on age-specific fitness. Hamilton proposed a full spectrum of selective forces each operating on age-specific fitness components, i.e. mortality and fertility. One of Hamilton’s expressions, possibly his most important, is of the same form as Medawar’s expression. But Hamilton’s selective forces on age-specific fitness components do not add up to yield Medawar’s selective force on age-specific fitness. It is concluded that Hamilton’s analysis should be considered neither as a correction to Medawar’s analysis nor as its obvious complement. |
format | Online Article Text |
id | pubmed-8616860 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | Springer International Publishing |
record_format | MEDLINE/PubMed |
spelling | pubmed-86168602021-12-01 Medawar and Hamilton on the selective forces in the evolution of ageing Giaimo, Stefano Hist Philos Life Sci Original Paper Both Medawar and Hamilton contributed key ideas to the modern evolutionary theory of ageing. In particular, they both suggested that, in populations with overlapping generations, the force with which selection acts on traits declines with the age at which traits are expressed. This decline would eventually cause ageing to evolve. However, the biological literature diverges on the relationship between Medawar’s analysis of the force of selection and Hamilton’s. Some authors appear to believe that Hamilton perfected Medawar’s insightful, yet ultimately erroneous analysis of this force, while others see Hamilton’s analysis as a coherent development of, or the obvious complement to Medawar’s. Here, the relationship between the two analyses is revisited. Two things are argued for. First, most of Medawar’s alleged errors that Hamilton would had rectified seem not to be there. The origin of these perceived errors appears to be in a misinterpretation of Medawar’s writings. Second, the mathematics of Medawar and that of Hamilton show a significant overlap. However, different meanings are attached to the same mathematical expression. Medawar put forth an expression for the selective force on age-specific fitness. Hamilton proposed a full spectrum of selective forces each operating on age-specific fitness components, i.e. mortality and fertility. One of Hamilton’s expressions, possibly his most important, is of the same form as Medawar’s expression. But Hamilton’s selective forces on age-specific fitness components do not add up to yield Medawar’s selective force on age-specific fitness. It is concluded that Hamilton’s analysis should be considered neither as a correction to Medawar’s analysis nor as its obvious complement. Springer International Publishing 2021-11-25 2021 /pmc/articles/PMC8616860/ /pubmed/34822012 http://dx.doi.org/10.1007/s40656-021-00476-6 Text en © The Author(s) 2021 https://creativecommons.org/licenses/by/4.0/Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . |
spellingShingle | Original Paper Giaimo, Stefano Medawar and Hamilton on the selective forces in the evolution of ageing |
title | Medawar and Hamilton on the selective forces in the evolution of ageing |
title_full | Medawar and Hamilton on the selective forces in the evolution of ageing |
title_fullStr | Medawar and Hamilton on the selective forces in the evolution of ageing |
title_full_unstemmed | Medawar and Hamilton on the selective forces in the evolution of ageing |
title_short | Medawar and Hamilton on the selective forces in the evolution of ageing |
title_sort | medawar and hamilton on the selective forces in the evolution of ageing |
topic | Original Paper |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8616860/ https://www.ncbi.nlm.nih.gov/pubmed/34822012 http://dx.doi.org/10.1007/s40656-021-00476-6 |
work_keys_str_mv | AT giaimostefano medawarandhamiltonontheselectiveforcesintheevolutionofageing |