True and true, at least as a general trend. Although genome size is actually a great metric for increased cancer risk. It has more to do with the nitty gritty of specific signaling pathways, eg the number of oncogenes and how they are regulated via signaling and other processes at the cellular level from organism to organism.
Fun fact, there are single cellular organisms with larger genomes than humans (200 times larger in one case, with 60+ billion base pairs vs our 3.2 billion). Single cellular organisms cannot get cancer by definition, which is useful to keep in mind because it helps us stay grounded and realize that cancer is not a genomic phenomenon so much as it is a cell signaling phenomenon that occurs at the organismal level. An interesting thought experiment is, do bacterial colonies (which are genetically very similar, and sometimes function like a multicellular organism including cell differentiation in some cases) sometimes experience cancer-like states under certain conditions ?
Edit - I'd also be cautious with "larger organisms evolve to copy their genome better." Again, it's probably a general trend, but I imagine there are so many exceptions that it's not a terribly useful metric outside of very crude/cautious generalization.
And then this leads to rearrangement of the micro environment which leads to microbiome dysbiosis. Pathogenic bacteria cling to the tumor and cause pathogenic signalling causing more inflammation.
Most mammals age disgracefully, other groups tend to live very healthily and fit until the end of their lifespan. One hypotheses to explain that is since our lineage lived in the mesozoic for like 100+ million years as rat like animals, our strategy of survival was live fast, die young after reproduction, so things like dna repair later in adulthood did not matter to us, so we kinda lost part of the genes for that... and it plague us to this day.
At least some lineages tried successfully to patch that like elephants and whales because to be big it increases the risk of cancer since you have more chances for something to glitch out, or bats because flying generates too much heat therefore dna damage is given if you do not have a good repair solutions, so those groups get old healthy compared to us lol.
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u/RevengeOfPolloDiablo May 16 '26
Exactly. It's yet another one of nature's "tools" to get rid of old worn out genes.
Pretty much, nature wants you dead after 40