A biological cell becomes cancerous if a certain set of rare mutations all happen in that same cell before its organism dies. This is quite unlikely to happen in any one cell, but a large organism has enough cells to create a substantial chance of cancer appearing somewhere in it before it dies. If the chances of mutations are independent across time, then the durations between the timing of mutations should be roughly equal, and the chance of cancer in an organism rises as a power law in time, with the power equal to the number of required mutations, usually around six.
In your analogy of cancer that isn't what happens across species. Peto's paradox is an observation that at the species level, the incidence of cancer does not appear to correlate with the number of cells in an organism. Elephants do not get cancer at the rate of elephant sized humans. Possibly because elephants have 20 copies of tumor suppressor gene TP53 in their genome, where humans and other mammals have only one. I don't think whales get cancer at all. How are we to know that the universe is filled with human like galaxies and not whale or elephant like galaxies. Wasn't there an article that suggested that phosphorus was not evenly spread out across the universe and don't we observe an over abundance of phosphorus on earth than the current model of galactic nucleosynthesis would suggest. One percent of stars cataloged have P. What if an over abundance of P is the difference between 1 tumor suppressor gene and twenty.
I can Google some research if desired, but for some reason I thought whales had normal incidence of cancer, but their huge size meant there was greater complexity/structure required for tumors to get big enough to threaten survival, which very rarely happens. Something like “their tumors get their own tumors.”
I'd guess the power law is changed, and is closer to the # of hard steps you would have naively estimate than to the revised higher estimate. As an example, suppose that there are 2 hard steps each occurring with probability epsilon per year, but they need to happen within 1 year of each other. Then the probability of happening within N years is N epsilon^2 rather than being quadratic in N. In general, a pair of hard steps that need to happen within 1 year (or that have say a 10%/year chance of getting undone) can just be modeled as a single hard step with a much lower rate, at least for the purposes of estimating P(life) as a function of planet age.
Which suggests that grabby aliens are out there, have now filled roughly half the universe, and will soon fill all of it, creating a deadline soon that explains why we are so early. And this power lets us estimate how soon we would meet them: in roughly a billion years.
What are the confidence/credible intervals for these? (half, billion)
Cancer rates can vary by organism type, and also change due to pathogens and environmental insult. Those aren't in conflict with the theory that they are caused by mutations.
I don't think cancer is especially common in enormous whales, which can live a very long time (bowhead whales are the longest living mammals). Greg Cochran would suggest cancer is more likely to be the result of pathogens or some novel environmental insult rather than random mutations you can calculate based on how many cells you have.
There is this:Why don't all whales have cancer? A novel hypothesis resolving Peto's paradoxhttps://pubmed.ncbi.nlm.nih...
But it's an explanatory model, not an observation.
In your analogy of cancer that isn't what happens across species. Peto's paradox is an observation that at the species level, the incidence of cancer does not appear to correlate with the number of cells in an organism. Elephants do not get cancer at the rate of elephant sized humans. Possibly because elephants have 20 copies of tumor suppressor gene TP53 in their genome, where humans and other mammals have only one. I don't think whales get cancer at all. How are we to know that the universe is filled with human like galaxies and not whale or elephant like galaxies. Wasn't there an article that suggested that phosphorus was not evenly spread out across the universe and don't we observe an over abundance of phosphorus on earth than the current model of galactic nucleosynthesis would suggest. One percent of stars cataloged have P. What if an over abundance of P is the difference between 1 tumor suppressor gene and twenty.
Ah, now if only we could figure out (and make use of?) the secret(s) of the stunning longevity of Greenland sharks. https://en.wikipedia.org/wi...
I can Google some research if desired, but for some reason I thought whales had normal incidence of cancer, but their huge size meant there was greater complexity/structure required for tumors to get big enough to threaten survival, which very rarely happens. Something like “their tumors get their own tumors.”
Well now that we have differing intuitions, that raises the priority of actually figuring out the answer.
I'd guess the power law is changed, and is closer to the # of hard steps you would have naively estimate than to the revised higher estimate. As an example, suppose that there are 2 hard steps each occurring with probability epsilon per year, but they need to happen within 1 year of each other. Then the probability of happening within N years is N epsilon^2 rather than being quadratic in N. In general, a pair of hard steps that need to happen within 1 year (or that have say a 10%/year chance of getting undone) can just be modeled as a single hard step with a much lower rate, at least for the purposes of estimating P(life) as a function of planet age.
You can read those roughly off of our graphs in our paper.
The notion of multiple set-backs occurring along the way seems very plausible to me.https://i.pinimg.com/origin...
Which suggests that grabby aliens are out there, have now filled roughly half the universe, and will soon fill all of it, creating a deadline soon that explains why we are so early. And this power lets us estimate how soon we would meet them: in roughly a billion years.
What are the confidence/credible intervals for these? (half, billion)
Cancer rates can vary by organism type, and also change due to pathogens and environmental insult. Those aren't in conflict with the theory that they are caused by mutations.
I don't think cancer is especially common in enormous whales, which can live a very long time (bowhead whales are the longest living mammals). Greg Cochran would suggest cancer is more likely to be the result of pathogens or some novel environmental insult rather than random mutations you can calculate based on how many cells you have.