How are animal cancer rates established in the first place? It seems like you'd have to go through the tissues of a large number of creatures to do this. Plus you have the issue that the carcasses you get might be selected unevenly, eg the cancer rate among zoo elephants might be different to the ones in the wild?
Seems like a mistake to assume drastic differences in the number of cell divisions between say humans and Elephants. Starting from one cell it's an exponential process so it's likely ~50 vs ~54 cell divisions or something.
Good quote from the article:<p>> Mel Greaves, a cancer biologist at the Institute for Cancer Research in London, agrees that TP53 cannot be the only explanation. “As large animals get bigger, they become more and more sluggish,” he notes, thereby slowing their metabolism and the pace at which their cells divide. And protective mechanisms can only do so much to stop cancer, he adds. “What would happen if elephants smoked and had a bad diet,” he says. “Would they really be protected from cancer? I doubt it.”
<i>That is surprising: the cells of large-bodied or older animals should have divided many more times than those of smaller or younger ones, so should possess more random mutations predisposing them to cancer.</i><p>Can a biologist reading this confirm that? I thought smaller organisms generally have much faster metabolisms to offset their shorter lifespans. Or is it the same at the cellular level?
I've read that big mammals (liek whales) can live through cancer without noticing, because cancer often mutates itself to death before it can kill the host.<p>Maybe that's another reason?
Anyone interested in Cancer has to read the Pulitzer prize winning book, The Emperor of All Maladies: A Biography of Cancer by Siddhartha Mukherjee. It's one of the most interesting non-fiction books I had ever read and in one of the latter chapters he mentions about the genes which prevent tumors (as discussed in the posted article).
There is a corellation between beeing hunted by a predator (external death stimulus) and not beeing hunted by a predator (internal death stimulus). Predators life a dangerous life, for them theire daily activity is a eds.
Obviously the benefits of cancer suppressing DNA in a population apply only if you are either to well hidden (naked mole rat, sloth) or to big to be predated (Rhino, Elephant, Whale).
Sorry, we as humans are part of a predatable species, so live fast and leave a devourable corpse for your descendants to mourn was our main strategy. If in search for human compatible cancer avoidance, the biggest interest should be on the most well hidden monkey - or the biggest (silverback).<p>Interesting is also how the re-productive cycle factors into this. If a individual takes a long time to grow up- cancer is a selector tortoises, if the reproduction is fast (mice/birds) cancer is basically not important. If every mice would get cancer after year 2 - the species still would continue.
Summary:<p>The gene TP53 is a tumour suppressor, that is activated when cell suffer DNA damage. The encoded protein either repairs or kills the cells, thereby preventing the cell to become cancerous.<p>Humans and most other mammals have only one copy of this gene, while Elephants (which are known for their very low cancer rates) have twenty copies of this gene.<p>Compared to other mammals, compromised Elephant cells are killed at a much higher rate, instead of being repaired.<p>However, this is most likely not the only factor at play.
They rarely eat sausages or other processed meats & were ahead of the game when "5-a-day" became "10-a-day" for fruit & veg.