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  1. 29 Apr '15 19:26 / 1 edit
    OK, here is my reasoning:

    I have picked the blue whale species in particular because they are the largest animals on Earth and you will see why that is relevant next:

    An adult blue whale's mass is typically about 180 tons
    An adult human's mass is typically about 1/12 tons
    So a typical human is about 12*180 = 2160 times more in mass.
    Lets call that 2000 times more.

    Now, assuming that the cells of a blue whale are about the same size as that of a humans (I tried googling this to check this but got nowhere ), and that the number of body cells in a mammal’s body is about proportional to its body size, an adult blue whale should have roughly about ~2000 more cells than a adult human.
    So that is 2000 times more cells that could mutate into a deadly cancer that will kill the animal. And, because it takes only one cell in the body to mutate to become a terminate strain of cancer, that means if each cell of the whale has the same probability of mutation into such a deadly strain of cancer as that of each human cell, that means there is up to a 2000 times more risk of the whale getting such a fatal cancer (actually, the maths of probability is more complicated than that and it will be at least a bit less than 2000 times the risk but, I think you get the idea ). But, if that is so, that would mean that every blue whale will almost inevitably get fatal cancer and they would have become extinct long ago as a result!

    But blue whales must have evolved to become so large from a much smaller species over many millions of years of evolution thus giving plenty of time for brutal Darwinian natural selection to evolve their cells to become much more resistant to becoming such a deadly cancer simply by the more cancer-prone whales being killed off by cancer. And, assuming an average blue whale is now no more prone to cancer than an average person, that means their cells have now evolved to be roughly about 2000 times less prone per cell to becoming cancerous than that of a human cell to compensate with having 2000 times more cells that could potentially become cancerous.

    Do you think this is a good theory based on valid reasoning?

    If my theory is correct, there may be some value in studying how blue whale cells are much more resistant to becoming cancerous because that may eventually lead to gene therapy or some other form of genetic engineering to make us humans more resistant to cancer. So I think it may be worth someone checking out my theory.
  2. 29 Apr '15 20:26
    Its not so simple. There are different causes of cancer and different types of cells are more susceptible. You probably should look at volumes of particular organs.
    In addition you must take age into account. Cancer risk goes up with age in humans and presumably does too with whales (which actually live about the same life span as first world humans do these days.
    Next, your body size estimates do not take into account the proportion of fat.
    Next you need to ask what types of cancer you are talking about and how lethal are they and what is the frequency in whales.
    Many cancers in humans are due to pollutants. It is possible whales are exposed to less pollutants or were in the past. Things like skin cancer from the sun in fair skinned people is caused by travel to places we didn't evolve.

    But you may still be on to something. Scientists also study very long living organisms to see how they avoid cancer.

    Oh, and whales don't smoke cigarettes and just that alone knocks off 5-10% of the risk of dying from cancer.
  3. 29 Apr '15 20:31
    http://www.bmj.com/content/347/bmj.f6833
  4. 29 Apr '15 20:55 / 1 edit
    Originally posted by twhitehead
    http://www.bmj.com/content/347/bmj.f6833
    Arr, so at least that link, if I am reading it right, implies that there probably isn't a lot of difference between the size of human cells and whale cells although I find it just a bit iffy to make that conclusion from that link because it doesn't directly say that.
  5. 29 Apr '15 20:56
    Originally posted by twhitehead
    Its not so simple. There are different causes of cancer and different types of cells are more susceptible. You probably should look at volumes of particular organs.
    In addition you must take age into account. Cancer risk goes up with age in humans and presumably does too with whales (which actually live about the same life span as first world humans do t ...[text shortened]... es don't smoke cigarettes and just that alone knocks off 5-10% of the risk of dying from cancer.
    Oh yes, I admittedly made a large number of simplifying assumptions there.
  6. 29 Apr '15 21:06
    Originally posted by humy
    Oh yes, I admittedly made a large number of simplifying assumptions there.
    I don't know for sure, but I think cell replication rates are very important. I think you would need to study a bit more about cancer before you would know whether you are really on to something.
    Also, even if it does turn out that whales are less susceptible to cancer, that won't necessarily help us deal with human cancers.

    With the advent of cheap DNA sequencing we are very close to finding many of the genetic susceptibilities to cancer, but knowing why you are susceptible to cancer doesn't automatically mean you can treat it - although it does help.
  7. Standard member Soothfast
    0,1,1,2,3,5,8,13,21,
    30 Apr '15 02:47
    Whales, usually being hundreds or thousands of feet underwater, are better protected from sources of radiation such as sunlight and cosmic rays. That may help.
  8. 30 Apr '15 06:42
    Originally posted by Soothfast
    Whales, usually being hundreds or thousands of feet underwater, are better protected from sources of radiation such as sunlight and cosmic rays. That may help.
    Actually whales spend a lot of their time on the surface. They are mammals and need to breathe air. But dark skin and the water probably do help to protect against skin cancer.
  9. Standard member DeepThought
    Losing the Thread
    02 May '15 19:41
    Originally posted by twhitehead
    I don't know for sure, but I think cell replication rates are very important. I think you would need to study a bit more about cancer before you would know whether you are really on to something.
    Also, even if it does turn out that whales are less susceptible to cancer, that won't necessarily help us deal with human cancers.

    With the advent of cheap D ...[text shortened]... u are susceptible to cancer doesn't automatically mean you can treat it - although it does help.
    I agree with what you're saying, but a major factor is the overall stability of the genome. Anatomically modern humans have been around for about 70,000 - 100,000 years. So our genome is set up for change. If point mutations are less suppressed in humans then cancer is more likely. Also the more successful a species is the less need there is for evolution to protect us from things like cancer.
  10. 02 May '15 20:30 / 8 edits
    Originally posted by DeepThought
    ... the more successful a species is the less need there is for evolution to protect us from things like cancer.
    But, surely, the evolution process, being totally mindless and without intelligence, is totally blind to how "successful" a species is as a whole and to any "need" that species may have as a whole.
    Evolution doesn't 'care' what happens or is happening to the evolving species.
    Even if there is a relatively 'small' survival/reproductive advantage of the individuals having an inheritable characteristic (such as greater resistance to cancer even if only ~2% of individuals currently get it ), natural selection will, if it can without it being counterproductive by doing so, slowly give that species that advantageous inheritable characteristic irrespective of how "successful" a species is or 'unsuccessfully' a species seems to be doing currently and irrespective of any "need" or lack of "need" for the species as a whole to have that characteristic for its survival.
    Evolution works more directly on the gene level and not exactly directly on the species level (remember the title of the book "the selfish gene" ).

    But, that said, I assume there to be a point where the relatively survival/reproductive advantage of the individuals having an inheritable characteristic may become so 'small' (such as greater resistance to cancer when already the species has evolved so that less than ~001% of individuals currently get it ) that there simply wouldn't be enough natural selection 'pressure' to even extremely slowly give that species that advantageous inheritable characteristic because there would be the constant interference from such things a genetic drift and, even it there is a very small survival 'cost' of having, say, greater resistance to cancer (such as making the species more prone to some other disease ) natural selection by even select against it!
  11. 02 May '15 20:38
    Originally posted by DeepThought
    I agree with what you're saying, but a major factor is the overall stability of the genome. Anatomically modern humans have been around for about 70,000 - 100,000 years. So our genome is set up for change.
    I don't understand what you are saying. Are you implying that humans are changing faster genetically than whales?

    If point mutations are less suppressed in humans then cancer is more likely. Also the more successful a species is the less need there is for evolution to protect us from things like cancer.
    Actually it usually has more to do with the age of reproduction, and typical time of death due to other causes. Generally any mutation that doesn't have a significant effect of reproduction stays. So a mutation that causes death after typical age of death due to other causes will have no problem spreading.

    But humys point is that if there are mutations in humans that cause us to get cancer more frequently than whales then comparing the genomes may lead to a better understanding of cancer and potentially prevention or cures.
  12. 02 May '15 20:43
    Originally posted by humy
    But, surely, the evolution process, being totally mindless and without intelligence, is totally blind to how "successful" a species is as a whole and to any "need" that species may have as a whole.
    The is however a strong effect relating to how many children a typical parent has. Animals that have fewer children per mother invest more into the survival of those children and thus should have lower rates of cancer (up to reproduction age).
  13. 09 May '15 14:28
    Originally posted by humy
    OK, here is my reasoning:

    I have picked the blue whale species in particular because they are the largest animals on Earth and you will see why that is relevant next:

    An adult blue whale's mass is typically about 180 tons
    An adult human's mass is typically about 1/12 tons
    So a typical human is about 12*180 = 2160 times more in mass.
    Lets call that 2000 ...[text shortened]... e us humans more resistant to cancer. So I think it may be worth someone checking out my theory.
    Peto's paradox.
  14. 09 May '15 15:01 / 2 edits
    Originally posted by C Hess
    Peto's paradox.
    Thanks for that!

    http://en.wikipedia.org/wiki/Peto%27s_paradox
    "...Peto's Paradox is the observation, due to Richard Peto, that at the species level, the incidence of cancer does not appear to correlate with the number of cells in an organism.[1] For example, the incidence of cancer in humans is much higher than the incidence of cancer in whales.[2] This is despite the fact that a whale has many more cells than a human. If the probability of carcinogenesis were constant across cells, one would expect whales to have a higher incidence of cancer than humans.

    Evolutionary considerations

    The evolution of multicellularity has required the suppression of cancer to some extent,[3] and connections have been found between the origins of multicellularity and cancer.[4][5] In order to build larger and longer-lived bodies, organisms required greater cancer suppression. Evidence suggests that large organisms such as elephants have more adaptations that allow them to evade cancer.[6] The reason that intermediate-sized organisms have relatively few of these genes may be because the advantage of preventing cancer these genes conferred was, for moderately-sized organisms, outweighed by their disadvantages—particularly reduced fertility.[7]

    A paper in Cell Reports in 2015 claimed to have found genes in the bowhead whale (Balaena mysticetus) that may be associated with longevity.[8]

    Metabolic considerations

    A 2014 paper in 'Evolutionary Applications' by Maciak and Michalak emphasized what they termed the "a largely underappreciated relation of cell size to both metabolism and cell division rates across species" as key factors underlying the paradox, and concluded that "larger organisms have bigger and slowly dividing cells with lower energy turnover, all significantly reducing the risk of cancer initiation." [9]
    ..."

    never heard of this Peto paradox before but this makes it evident that my OP idea isn't new.
  15. 11 May '15 21:19
    Originally posted by humy
    ...never heard of this Peto paradox before but this makes it evident that my OP idea isn't new.
    Quite right, but good thinking.