{"id":765478,"date":"2026-06-28T09:54:12","date_gmt":"2026-06-28T09:54:12","guid":{"rendered":"https:\/\/www.newsbeep.com\/au\/765478\/"},"modified":"2026-06-28T09:54:12","modified_gmt":"2026-06-28T09:54:12","slug":"the-shadow-in-evolution-that-explains-why-long-life-comes-at-a-cost-sciencealert","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/au\/765478\/","title":{"rendered":"The ‘Shadow’ in Evolution That Explains Why Long Life Comes at a Cost : ScienceAlert"},"content":{"rendered":"

The world’s population is shifting. We’re living longer<\/a> than ever before, with elderly people taking up a greater proportion of the people on the planet.<\/p>\n

And yet those extra years aren’t necessarily being enjoyed in good health<\/a>.<\/p>\n

So how do these shifts interact with what we know about genetics and evolution<\/a>? How might old age \u2013 a relatively recent concept, in the history of Homo sapiens \u2013 change our species<\/a>?<\/p>\n

And is the association between getting older and being less healthy inevitable?<\/p>\n

To try to answer those questions, evolutionary geneticists Handan Melike D\u00f6nerta\u015f and Linda Partridge reviewed several huge modern-day genetic datasets to test an idea that’s been around since the mid-20th century: the ‘selection shadow’<\/a>.<\/p>\n

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“Advances in comparative genomics, large-scale human genetic studies and multi-omics aging biomarkers now enable rigorous testing of evolutionary predictions,” write<\/a> the researchers in their published paper.<\/p>\n

The selection shadow concept is the idea that the natural filtering carried out by evolutionary pressures \u2013 the classic ‘survival of the fittest’<\/a> mantra \u2013 is driven by the need for a species to reproduce.<\/p>\n

Once the next generation has arrived, however, how fit or otherwise we are matters much less in evolutionary terms.<\/p>\n

That impacts health in old age in a couple of ways. First, harmful genetic mutations that manifest themselves when we’re elderly aren’t being weeded out by evolution \u2013 at that stage, we’ve already had kids.<\/p>\n

Second, genes that are helpful in youth and damaging in old age are also kept around, because evolution strongly favors the early benefits.<\/p>\n

\"SelectionThe force of natural selection declines with age. It operates strongly on harmful mutations in early life (A) but weakens over time, allowing other, less potent mutations to accumulate (C), even if they are detrimental in later life (B). (D\u00f6nerta\u015f & Partridge, Nat. Rev. Genet., 2026)<\/p>\n

For example, if a gene or gene variant increases cancer risk<\/a> in old age but helps you reproduce in your 20s and 30s, that’s a good trade-off from an evolutionary perspective.<\/p>\n

That’s the theory \u2013 and because we now have so much more genetic data to analyze, D\u00f6nerta\u015f and Partridge were able to see how it stacks up against the available evidence.<\/p>\n

“An evolutionary view of aging isn’t just a historical curiosity,” says<\/a> D\u00f6nerta\u015f, from the Fritz Lipmann Institute in Germany.<\/p>\n

“It points to the conserved, ancient pathways whose continued activity in later life contributes to age-related disease, and where interventions are therefore most likely to work.”<\/p>\n

The researchers referred to several<\/a> studies<\/a>, covering hundreds of thousands of individuals, that highlight weaker natural selection in old age \u2013 essentially confirming the selection shadow is real.<\/p>\n

They didn’t stop there.<\/p>\n

\"AgeingGenes associated with aging hallmarks, such as chronic inflammation and stem cell<\/a> exhaustion, are consistent across species, the researchers found. (D\u00f6nerta\u015f & Partridge, Nat. Rev. Genet., 2026)<\/p>\n

D\u00f6nerta\u015f and Partridge also looked at how old age looks different in different species, such as the long-living mole rat<\/a>. Biological tricks that these species use to work around the selection shadow could help inform research into healthy aging for humans, too.<\/p>\n

In other words, a deeper understanding of aging from an evolutionary perspective will give us clues about how aging might be modified.<\/p>\n

“It also reframes the goal: not simply extending lifespan, but partially relieving the late-life costs of a biology that natural selection optimized for early life \u2013 so that more of life is spent in good health,” says<\/a> Partridge, from the University College London.<\/p>\n

There’s also wide variability in the lifespan of humans,<\/a> of course, which the researchers also noted.<\/p>\n

\"Subscribe<\/a><\/p>\n

Fundamentally, we get older and eventually die because our cells wear out<\/a>.<\/p>\n

But there’s the tantalizing prospect<\/a> that there might be ways to shift the body’s priorities to some extent, and this review offers a new angle on how that might be done.<\/p>\n

“The selection shadow that permitted aging to evolve now offers a framework for reversing its consequences,” write<\/a> the researchers.<\/p>\n

Related: Younger Adults May Be Aging Faster Than Previous Generations<\/a><\/p>\n

“Aligning evolutionary theory with mechanistic studies and human genomics will enable research to advance from cataloging age-related changes to rationally targeting their upstream causes, compressing morbidity and extending human healthspan.”<\/p>\n

The research has been published in Nature Reviews Genetics<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"The world’s population is shifting. We’re living longer than ever before, with elderly people taking up a greater…\n","protected":false},"author":2,"featured_media":765479,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[64,63,2967,128],"class_list":["post-765478","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-au","tag-australia","tag-msft-content","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/765478","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=765478"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/765478\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/765479"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=765478"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=765478"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=765478"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}