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Related [0], large animals seldom get cancer, at least at rates much lower than humans, which is surprising considering how many more cells they have (each of w

• Retric 7y ago
  Human vision goes years before our cancer rates spike. We are essentially living past our primitive life expectancy until something fails which is very recent and evolution has had little time to catch up to this. At a nuts and bolts level cell volume is less indicative of cancer as interfaces like skin, lungs, and intestines are vastly more likely to get cancer than most other tissues. Early cancers are often the result of mutations during growth from a single cell which is closer to log(volume) vs simple volume in terms of risks.
  • fpoling 7y ago
    It is only ability to focus that goes down so for a person without myopia only near vision is affected. This is still bad as it affects the gatherer part of hunter-gazerer society, but it does not imply that evolution has not tried to optimize vision for people over 40 years old. They still can spot a lion far away.
    • Retric 7y ago
      Quite a bit breaks down with age including a massive reduction in night vision. https://www.allaboutvision.com/over60/vision-changes.htm https://www.allaboutvision.com/over60/vision-changes.htm This might not seem like a major issue to us, but would be if trying to walk around by starlight at night.
      • fpoling 7y ago
        That does not imply that evolution has not tried. Human ancestors had much shorter life span and even millions of years can be not enough to fully adapt the vision for a longer lifespan especially when things works good enough. Witness flatfish. We have good records for species to see that it took tenths of millions years for eyes to move 90 degrees on the head after fish ancestors decided to lay flat on the side on ocean floor. It was good enough for the fish to see with single eye most of the time and evolution had little room for improvements since any wrong move with change in vision implied no vision and death.
        • Retric 7y ago
          Evolution has clearly been doing quite a bit. But, so much about our environment has been changing so quickly it’s more like a first pass than the deep optimization you see with say sharks. If the Bronze Age had lasted 10+ million years many things would have changed.
  • beefield 7y ago
    > . We are essentially living past our primitive life expectancy until something fails which is very recent and evolution has had little time to catch up to this. To my naive understanding of evolution, it has little incentive to fix anything that breaks after reproduction age. So I would not expect evolution to catch on cancer ever.
    • toxik 7y ago
      In particular for primates, the elderly help the community and this is obviously beneficial for survival and reproduction.
      • crazydoggers 7y ago
        The elderly would have to specifically help their own grandchildren, not just the community, for evolution to have an effect (otherwise you’re talking group selection nonsense). I’d imagine it’s debatable whether elderly grandparents past reproductive years are helping their grandchildren be more reproductively successful. Possible, but not a forgone conclusion by any means.
        • deleted 7y ago
          [deleted]
        • barry-cotter 7y ago
          Grandmothers increase their offspring’s genetic impact, for daughters by increasing survival rates, for sons by increasing numbers of offspring. http://en.wikipedia.org/wiki/Grandmother_hypothesis http://en.wikipedia.org/wiki/Grandmother_hypothesis > The grandmother hypothesis is a hypothesis to explain the existence of menopause in human life history by identifying the adaptive value of extended kin networking. It builds on the previously postulated "mother hypothesis" which states that as mothers age, the costs of reproducing become greater, and energy devoted to those activities would be better spent helping her offspring in their reproductive efforts. It suggests that by redirecting their energy onto those of their offspring, grandmothers can better ensure the survival of their genes through younger generations.
  • lordnacho 7y ago
    > Human vision goes years before our cancer rates spike. But is this due to how we use our eyes? I always wondered how it could be that maybe half of everyone I knew in uni used glasses, when you'd think a 20-year old hunter-gatherer would need to be able to see stuff.
    • barry-cotter 7y ago
      Different mechanisms of action. Age related deterioration of eyesight, presbyopia, is caused by hardening of the lens and weakening of focusing muscles. Myopia is probably caused by lack of exposure to the extremely bright light of the sun during childhood and adolescence. Twenty year old hunter gatherers have great eyesight, sixty year old ones, not so much.
      • justjash 7y ago
        > Myopia is probably caused by lack of exposure to the extremely bright light of the sun during childhood and adolescence Is there research on this? Just wondering since I ended up having issues with nearsightedness in my early 20s but feel like I spent a lot more time outdoors as a child compared to children these days.
        • ashelmire 7y ago
          Yes, google it.
    • walterbell 7y ago
      > I always wondered how it could be that maybe half of everyone I knew in uni used glasses There are many possible factors, including genetics, light exposure, amount of time spent on closeup vs distance, and a shortage of vision therapy / behavioral optometry experts. https://gettingstronger.org/2016/03/faq-for-vision-improvement-by-hormetism/ https://gettingstronger.org/2016/03/faq-for-vision-improveme...
  • criley2 7y ago
    >We are essentially living past our primitive life expectancy until something fails I will chime in and say "not really". If a human makes it past say 10 years old (even really makes it past 2 years old), odds are they make it to 55-80 without modern medicine, civilization, etc. The only reason life expediencies appear lower than 50 (all the way down to the 30s) in places and in eras is due to insane infant mortality driving the numbers down. The life expectancy of those who make it to 2 years old is dramatically higher than that general life expectancy number.
    • falcor84 7y ago
      >The only reason life expediencies appear lower than 50 (all the way down to the 30s) in places and in eras is due to insane infant mortality driving the numbers down. Violence (leading to either immediate death, or due to infection) and epidemics (e.g. HIV) are also very significant factors.
    • tuxone 7y ago
      The likelihood of making it past 2-10 years old depends on modern medicine and civilization. So does marking it up to 55-80
      • Ensorceled 7y ago
        You are agreeing with the parent on the first part and simply disagreeing with the parent, without any evidence, on the second part.
        • glenneroo 7y ago
          I understood GP's comment to mean that modern medicine and civilization are the reason for both parts.
      • Amezarak 7y ago
        The effect of modern medicine is actually mostly muted in the data, excluding infant mortality, because of other factors (diet, fitness, environment.) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2672390/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2672390/ Between 1850-1880, life expectancy in England was as long or longer than it is now. This predates antibiotics and nearly all vaccines, let alone what we today think of as advanced medical care.
• arcticbull 7y ago
  Elephants in particular almost never get cancer. [1] [1] https://www.nbcnews.com/health/health-care/why-don-t-elephants-get-cancer-new-gene-study-explains-n854321 https://www.nbcnews.com/health/health-care/why-don-t-elephan...
  • danieltillett 7y ago
    That is because they stave to death when their sixth set of teeth wear out. To get cancer at anything similar to human rates elephants need to live longer.
    • close04 7y ago
      They are also exposed to far less carcinogens. Half of cancers as far as I read on Wikipedia can be attributed to artificial factors like smoking, alcohol, diet triggered obesity, etc.
      • ivanhoe 7y ago
        It's always a combination of genetic predisposition and external effects working together (except, of course, in very rare cases of lethal-dose exposures to carcinogens). Usually external effects just increase the chances of mutations, and then fate and your genetics role the dice.
      • hevi_jos 7y ago
        Not to forget Chemicals like PVCs plasticizers, solvents like benzene in paints, bis-phenol A in plastic bottles, flame retardants in our home that we breathe whenever we sit down in something soft, insecticides(air in cities is super polluted of them) and diesel particles. Those things are extremely dangerous, but we have not natural sensors to detect and avoid exposure to them. I bought a geiger detector and it surprised me to find places with thousands of times more radiation than others.
        • ethbro 7y ago
          Don't put it near a banana...
• whiddershins 7y ago
  There are many theories, but one fun one is that the cancer gets cancer: https://academic.oup.com/icb/article/47/2/317/719209 https://academic.oup.com/icb/article/47/2/317/719209
  • dalore 7y ago
    My favourite is that cancer and glucose are linked https://www.ncbi.nlm.nih.gov/pubmed/16892078 https://www.ncbi.nlm.nih.gov/pubmed/16892078 so removing glucose starves the cancer.
• mac01021 7y ago
  Don't larger animals tend to have lower metabolic rates (per cell)? That could easily be the relevant factor.