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Elephants have solved cancer. Their larger size is due to more cells (not bigger cells), so they would be more at risk of cancer. But they've evolved to have m

Elephants have solved cancer. Their larger size is due to more cells (not bigger cells), so they would be more at risk of cancer. But they've evolved to have more TP53 genes, so their lifetime risk of cancer is around 5%: https://www.nih.gov/news-events/nih-research-matters/how-elephants-defend-against-cancer https://www.nih.gov/news-events/nih-research-matters/how-ele...

Gatsky 4y ago
This isn’t quite right, elephants do have bigger cells as well, so 1kg of elephant has fewer cells than 1kg of mice. There is also the fact that metabolism shows sub linear scaling with body mass. Geoffrey West has various papers about this. As well as all that, elephant cells are intrinsically more cancer resistant as you point out.
hetspookjee 4y ago
You can also add naked mole rats to that pile.
robocat 4y ago
> Elephants have solved cancer. Unfortunately untrue. You are referring to https://en.wikipedia.org/wiki/Peto%27s_paradox https://en.wikipedia.org/wiki/Peto%27s_paradox but as you say 5% of Elephants still die of cancer. Elephants have evolved other mechanisms to protect against cancer because they have more cells (more copy errors) https://www.sciencedaily.com/releases/2021/02/210204131438.htm https://www.sciencedaily.com/releases/2021/02/210204131438.h... When thinking of cancer, try to think of the incentives of the organism to avoid copying errors, which are eventually deadly. So many deaths are direct effects of copying errors (cancer), that the human body gives most cells a lifetime of ~40 duplications (https://en.wikipedia.org/wiki/Hayflick_limit https://en.wikipedia.org/wiki/Hayflick_limit measured by telomeres) before killing off cells (cell senescence). Senescence causes the majority of other deaths i.e. the root cause of death is often indirectly due to the body’s mechanisms to prevent cancer. The mechanism to cause senescence has to be robust to error, so that mutations are unlikely to defeat cell death. A metaphor: the body tries to keep the tree of all cell duplications as a balanced tree - and cancer is when one node has enough error that it can reproduce and unbalance the tree. https://royalsocietypublishing.org/doi/10.1098/rstb.2016.0448 https://royalsocietypublishing.org/doi/10.1098/rstb.2016.044... links to better information, and it has a lovely summary: “We assume that selection favours short telomeres as a mechanism to protect against cancer. At the same time, selection favours long telomeres as a protective mechanism against DNA damage and replicative senescence.” We have evolved compromises that protect us against DNA copying errors, but those compromises are imperfect (from a longevity POV). Cancer is an area where there is extensive misinformation as to the root causes, and “the cure for cancer” is non-sensical: the cure would require eliminating DNA errors in all cells within the body. Currently we can fix some individual errors (specific cancer therapies), or attack dividing cells.

Gatsky 4y ago

This isn’t quite right, elephants do have bigger cells as well, so 1kg of elephant has fewer cells than 1kg of mice. There is also the fact that metabolism shows sub linear scaling with body mass. Geoffrey West has various papers about this. As well as all that, elephant cells are intrinsically more cancer resistant as you point out.

hetspookjee 4y ago

You can also add naked mole rats to that pile.

robocat 4y ago

> Elephants have solved cancer. Unfortunately untrue. You are referring to https://en.wikipedia.org/wiki/Peto%27s_paradox https://en.wikipedia.org/wiki/Peto%27s_paradox but as you say 5% of Elephants still die of cancer. Elephants have evolved other mechanisms to protect against cancer because they have more cells (more copy errors) https://www.sciencedaily.com/releases/2021/02/210204131438.htm https://www.sciencedaily.com/releases/2021/02/210204131438.h... When thinking of cancer, try to think of the incentives of the organism to avoid copying errors, which are eventually deadly. So many deaths are direct effects of copying errors (cancer), that the human body gives most cells a lifetime of ~40 duplications (https://en.wikipedia.org/wiki/Hayflick_limit https://en.wikipedia.org/wiki/Hayflick_limit measured by telomeres) before killing off cells (cell senescence). Senescence causes the majority of other deaths i.e. the root cause of death is often indirectly due to the body’s mechanisms to prevent cancer. The mechanism to cause senescence has to be robust to error, so that mutations are unlikely to defeat cell death. A metaphor: the body tries to keep the tree of all cell duplications as a balanced tree - and cancer is when one node has enough error that it can reproduce and unbalance the tree. https://royalsocietypublishing.org/doi/10.1098/rstb.2016.0448 https://royalsocietypublishing.org/doi/10.1098/rstb.2016.044... links to better information, and it has a lovely summary: “We assume that selection favours short telomeres as a mechanism to protect against cancer. At the same time, selection favours long telomeres as a protective mechanism against DNA damage and replicative senescence.” We have evolved compromises that protect us against DNA copying errors, but those compromises are imperfect (from a longevity POV). Cancer is an area where there is extensive misinformation as to the root causes, and “the cure for cancer” is non-sensical: the cure would require eliminating DNA errors in all cells within the body. Currently we can fix some individual errors (specific cancer therapies), or attack dividing cells.