Comment on Is it true that the natural lifespan of humans is only 38 years old and we only live past that because of loads of modern medicines/technology?

owenfromcanada@lemmy.ca ⁨1⁩ ⁨day⁩ ago

• krooklochurm@lemmy.ca ⁨1⁩ ⁨day⁩ ago

  Poopypoops?

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• Buffalox@lemmy.world ⁨1⁩ ⁨day⁩ ago

  Average lifespan used to be shorter because of the amount of infant mortality.

  That is completely wrong. discovermagazine.com/what-was-the-life-expectancy…

  Other research reveals that the lifespan of Homo sapiens may have changed from the Middle Paleolithic to the later Upper Paleolithic, since the ratio of older to younger remains increases. The same research shows that starting about 30,000 years ago at the beginning of the Upper Paleolithic, the average lifespan began to push past 30 years.

  Note that Lifespan is NOT the same as life expectancy:

  my.clevelandclinic.org/health/articles/lifespan

  Lifespan is the maximum length of time that a person can live

  So 30000 years ago 30 years was pretty much the maximum age a person could achieve. Life expectancy would probably have been 15-20.

  Read my other comment, the study is probably pretty close to the truth.
  lemmy.world/comment/19682894

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• Talonflame@lemmy.cafe ⁨1⁩ ⁨day⁩ ago

  According to the article it’s not about life expectancy, but that the lifespan of 38 is hardcoded into our DNA/Telomeres

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  • AbouBenAdhem@lemmy.world ⁨1⁩ ⁨day⁩ ago

    Unless I missed something, the word “telomeres” doesn’t occur in the article or its source paper—rather, it discusses the rate of DNA methylation.

    IMO, the key passage in the paper is this:

    However, any genetic regulation for a species may potentially be a secondary factor as there may be other environmental selective pressures. This may be the case with species which have lifespans post reproductive age and therefore, there may be non-genetic factors that may be more predictive of their maximum lifespan.

    I suspect that the methylation rate is actually tracking the end of the reproductive stage of the lifecycle, rather than the length of the lifecycle as a whole.

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    • Talonflame@lemmy.cafe ⁨1⁩ ⁨day⁩ ago

      It’s saying 38 is basically the maximum lifespan of a human and the only reason we live past 38 is due to unnatural interventions ie medicines

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      • AbouBenAdhem@lemmy.world ⁨1⁩ ⁨day⁩ ago

        It’s saying 38 is the maximum lifespan predicted by their model—but it also says their model has an R^2 of 0.76, meaning their model only accounts for about 76% of the actual measured variation. And then they mention other factors that could account for the remaining 24% of the variation, including post-reproductive-age lifespan.

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  • owenfromcanada@lemmy.ca ⁨1⁩ ⁨day⁩ ago

    I’m not sure what the difference between “lifespan” and “expectancy” is other than semantics, given the context of your questions. Regardless of what our DNA says, our life expectancy is typically in the 70s or 80s, and that hasn’t changed much throughout known human history, so it has nothing to do with modern technology.

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    • Talonflame@lemmy.cafe ⁨1⁩ ⁨day⁩ ago

      Life expectancy can be affected by things like infant deaths, disease, etc.

      lifespan is the age an animal is designed to live for. The study (which was published in Nature btw) implies that humans reaching past 38 is unnatural and only a result of luck and modern technology.

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      • missingno@fedia.io ⁨1⁩ ⁨day⁩ ago

        Humans lived past 38 long before modern technology.

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      • Tenniswaffles@lemmy.blahaj.zone ⁨1⁩ ⁨day⁩ ago

        pmc.ncbi.nlm.nih.gov/articles/PMC2625386/

        sc.edu/…/conversation-old-age-is-not-a-modern-phe…

        sapiens.org/…/life-expectancy-measure-mispercepti…

        Logically, average life expectancy cannot be higher than average lifespan. For that to be true would mean that more people who made it out of childhood lived past their expected lifespan than didn’t, which doesn’t make sense.

        If the expected lifespan is 38, than the average life expectancy before medical science advanced to the point where we could extend it should be lower than 38, but we in fact know that more often than not if you made it out of childhood in the past your chances of making it to 50+ were good, barring disease, war or what have you.

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