study<\/a> published today in Nature examined the records of 117 captive mammal species, from lions to rats. The data revealed a pattern: when animals stop reproducing \u2013\u00a0whether through hormonal contraception or surgical sterilisation \u2013\u00a0they tend to live longer.<\/p>\nMuch longer.<\/p>\n
\u201cThe increase in life expectancy averaged between 10 and 20% across species. These findings offer some of the strongest evidence yet for one of evolutionary biology\u2019s central ideas: reproduction shortens lifespans,\u201d says UNSW coauthor Dr Malgorzata Lagisz.<\/p>\n
Evolutionary theory predicts the energy invested in producing and raising young is energy taken away from repairing cells, fighting infections or maintaining the body\u2019s long-term health. Yet, in mammals, evidence for this has so far been inconsistent \u2013\u00a0mostly because of a lack of large and comparable datasets across species.<\/p>\n
Zoo datasets changed that. Here, well-documented birth and death data sit alongside data on hormonal contraception or surgical sterilisation, which is administered to prevent surplus animals, maintain genetic diversity, manage behaviour or for health reasons.<\/p>\n
By tapping into these extensive life-history records, researchers could build a picture of longevity across mammals of all sizes, diets and life strategies.<\/p>\n
Their results suggest hormones may interact with pathways that regulate the biology of ageing. But while the relative increase in lifespan was similar in males and females, there were different underlying reasons.<\/p>\n
\u201cIn males, only castration extends lifespan \u2013 not vasectomy \u2013 which indicates that the effect comes from removing sex hormones,\u201d says lead author Associate Professor Mike Garratt from the University of Otago.<\/p>\n
A vasectomy prevents reproduction but leaves testosterone production intact, while castration removes both the testes and the hormones they produce.<\/p>\n
Dr Lagisz says this distinction matters.<\/p>\n
\u201cSex hormones shape the development of individuals,\u201d Dr Lagisz says. \u201cThe biggest longevity boosts occurred when males were castrated early in life.\u201d<\/p>\n
Comparing the sexes<\/p>\n
Without testosterone, males likely engaged in fewer risky, aggressive behaviours that often lead to injury or early death. But, Dr Lagisz says, the influence of sex hormones reaches deeper \u2013\u00a0into the cellular and molecular machinery of ageing itself.<\/p>\n
In females, the pattern was different. While contraception or surgical sterilisation consistently extended female lifespans across species, timing didn\u2019t matter. Early-life and later-life interventions both produced similar benefits.<\/p>\n
Here, the reason is energetic.<\/p>\n
\u201cPregnancy, lactation and repeated reproductive cycles are not only metabolically taxing but can weaken the immune system,\u201d Dr Lagisz says.<\/p>\n
Without such physiological demands, females retain more resources to fuel their immunity and tissue repair \u2013\u00a0and are less likely to die from infection and infectious diseases.<\/p>\n
\u201cIt\u2019s not just one hormonal mechanism,\u201d Dr Lagisz says. \u201cIt\u2019s the cumulative cost of females making and supporting offspring.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"Drawing on data from more than 100 mammal species, an international team of researchers examined the trade-off between…\n","protected":false},"author":2,"featured_media":341245,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[64,63,69596,1325,137,111612,337,128,88733,69597,69598],"class_list":["post-341244","post","type-post","status-publish","format-standard","has-post-thumbnail","category-health","tag-au","tag-australia","tag-division-of-equity-diversity-inclusion","tag-general","tag-health","tag-healthy-lives","tag-research","tag-science","tag-science-tech","tag-sdg","tag-sdg3"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/341244","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=341244"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/341244\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/341245"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=341244"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=341244"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=341244"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}