It is also being researched how endogenous retroviruses are part of aging. The very rough idea being that at some point long in past a retrovirus became endogenous and provided a pathway for aging increasing the evolutionary rate of that organism, which would then out-compete most of the immortal organisms with time.
Endo is internal, exo is external. Another example is endonym/exonym (nym is the particle for name): endonym - the name a group gives itself, exonym - the name outsiders give a group.
Genous, you can think of it as analogous with genesys, it's the root word for creation.
That's incredibly interesting! Do you know some (pop)science books that could help learn more about viruses? I found two that sound good from description: "Viruses: A Very Short Introduction" by Dorothy H. Crawford and "A Planet of Viruses" by Carl Zimmer. Would you recommend any of these or something else?
I'm not really in a position to suggest a good book on viruses. I found out about this from a pop-sci book on latest research on aging and longevity.
When it comes to viruses though, there's one more very fascinating hypothesis. That the cell nucleus itself was once actually a virus that took over some bacteria to do its bidding.
Red queen gives some perspective on evolutionary arms race between hosts and pathogen. Virus is a piece of genetic material, so to understand a virus one needs to understand how a gene evolves.
It’s not a science book, but this did bring to mind an enjoyable sci-fi book by Greg Bear called Darwin’s Radio, for reasons that’ll be obvious: https://en.wikipedia.org/wiki/Darwin%27s_Radio
And the unusual factor that certain species adopted an intergenerational social system (which makes longer lifespan slightly more advantageous).
Thus we have some species nurturing their young (most mammals, marsupials, and birds) as opposed to spawning them and then going on to other things (e.g. fish, insects).
The most extreme case of this is humans: females live well beyond their fertile age and, effectively, so do men (while technically fertile in their 70s, the offspring are not as vigorous, in the evolutionary sense, as those conceived when the father was in his 20s). It is believed that this is because older humans have learned lots of things that can be useful in keeping kids alive and effective until they can propagate their genes.
Although 99+% of evolutionary psychology is utter bullshit this is nonetheless fascinating.
Biological immortality is the technical term for organisms which do not die unless killed, or more accurately where rate of mortality from senescence does not increase with chronological age.
They're similar but distinct concepts. Negligible senescence means after a point aging doesn't negatively affect the organism. They don't lose reproductive capability or experience functional decline. Imagine being 20 forever.
Biological immortality means after some point mortality rates don't increase with age - you can still grow old, it just won't directly kill you. Biologically immortal organisms don't have a max lifespan, if they're lucky they can just keep on going, but they may be dramatically more feeble than their younger counterparts.
I think some Lobsters and Crocodiles are in the later category. Immune to cancer, their cells divide without limit over the years. So they never stop growing. The enormous ones are the oldest, and have a size fitness advantage in hunting and other combat, but a counter balancing fitness disadvantage in their increased needs.
I'm not aware of a context where immortal refers to organisms that can't be killed by accidents and predators. In mythology and novels alike, vampires, gods, elves, ..., are all called immortal and still can be killed.
I thought crocodiles or alligators (forget which one) were immortal and they tend to die only because they get so big and can't eat enough to maintain life eventually. But, they're not on this list?
>> The very rough idea being that at some point long in past a retrovirus became endogenous and provided a pathway for aging increasing the evolutionary rate of that organism, which would then out-compete most of the immortal organisms with time.
No virus needed. Humans are currently (or were very recently) under enormous evolutionary pressure to get smarter. The ability to adapt is likely itself a trait as you suggest, but it makes sense that it can vary over time as needed depending on environmental factors.
Something like:
https://pubmed.ncbi.nlm.nih.gov/20346965/