From an evolutionary perspective, and that of the article, those factors don't matter.
Exactly my point... except the article is muddying the water on the point, first making the point and then dismissing it. There's no direct means by which life beyond reproductive age "can" exercise a direct influence on selection. It will be true, of course, that old guys defending the homestead confers advantages on those younger... there's value in the genetic contribution, if there is one, that enables that utility beyond reproductive age... contributions... instead of having the old guys be dead weight that has to be carried entirely at the expense of the younguns who don't gain a benefit. Blurring the lines between genetics and culture isn't a new thing... and we're not going to resolve it here...
A species life expectancy may vary depending on the factors your site, BUT no amount of social safety net can change the *maximum* lifespan.
I don't think that's at all clear... first because it isn't very clear what the maximum life span is... or should be.
We do understand aging SO much better now than we did a generation ago... that if you are intent on doing it, today, you can at least slow the clock and live a lot longer than predecessors could. And, there are elements in which aging can be reversed, to a degree... No one I see is talking about adding on new telomeres yet... to rewind the clock in strictly genetic terms... but, we've only known about that for a decade or two now ? We're getting pretty close to being able to extend the average to 100 and beyond... maybe still see something closer to a limit at 130... but we have no idea, still, what the impacts of recent discoveries will be... when someone just born this year applies the lessons learned over a life time ?
We're not talking aborted baby blood infusions or anything like that... but, of course, that's out there... even if it isn't being widelty publicized that people are doing that...
And, then... we're also not talking near speed of light travel... which adds another wrinkle to consider... as time, in time, might prove to be just as (more) fungible as the operation of the clocks are proving now... but, that's well beyond the issue of the genetics, of course.
For most species, being non-productive means the last season of life. Many even die once they have reproduced. So why do humans have such an exceptionally long lifespan? Why is it that we live for so many years after menopause?
Pretty sure I've met more than my share of women who had just a bit too much of the black widow in them... who would happily enough shorten your life for you, that way, if you'd let them ? Here's to better choices and happy returns.
Being a bit more conspiratorially minded... it would also be rational, perhaps, to think the reason we live longer than other species do is that there's great advantage in it for the medical industrial establishment and insurance companies... throw in the leisure industry... RV sales would implode if you worked until you died without taking a few years off at the end ? So the answer is... its more profitable ? Old people surviving longer gives young people more of a reason to live... going to work and paying taxes to support them ?
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The intriguing idea there is so that grandparents can pass on their wisdom to their grandchildren and in the process improve the survival rate of the species. Think about it - Children take care of their parents, and their parents take care of their grandchildren. This cycle has a lot of positives to it which you cannot find in other species.
Are they right? I don't know. But I can imagine that humanity would not be what it is today if older generations could not pass on the benefit of their wisdom to the younger ones.
I don't think there are many questions about the relative advantage of having intact and cross generational families and a culture that values self sufficient units that can survive life's challenges...
It is a wide open question how much of that is a function of genetic predisposition or how much influence the choices of a family, or the larger cultural framework, has in influencing whatever genetic component there is to the "relative advantage" that selective pressures might operate upon.
That it is beneficial to survival... doesn't make it genetic...
>> As gene editing technology advances... I don't think you will be able to stop people using it.
Netflix has a new documentary series, "Unnatural Selection." I think you will enjoy it.
I probably will... but, currently on strike from all other forms of media... other than SI and the selected flows in my news feeds on the laptop... for a variety of reasons, as is true of most decisions... But, way too much advertising, way too much crap, way too much time wasted battling with it all... for WAY too little value.
Off the topic but... Changes occurring rapidly now in the digital landscape... making privacy increasingly impossible... and at the same time doubling down on the external imposition of selected narratives in diametric opposition to a "free press" and free choice. I don't support it. So, I'm working on eliminating all my interfaces with the increasingly evil Google companies... already limited to very spare use of gmail and Youtube... done with them. Not any higher regard for Netflix or Amazon...
By choice I'm back to listening to the radio more... and reading a lot more... and enjoying that a lot more than I thought I would. Got a backlog in a stack of Science magazines that need to be read...
I do know people who are active advocates of more deliberate selection... focused on solving problems that "can" be solved that way, as ridiculous... or immoral... as that sounds. Space travel... would be a lot easier if astronauts were scaled more like Homo luzonensis... so, why not make some ? Sticky wickets to navigate there in re-writing laws to define who gets to make choices like that... for others ? My opinion is: No. But, however that discussion turns out here in the U.S., it won't limit what they do in China... where they're already harvesting organs from people who are guilty of nothing other than... being out of favor with the state ?
We're seeing technology running well out ahead of human capacity to make wise choices, again...
There is clearly a strong correlation between fertility and longevity.
Or, many correlations... True in the negative sense that animals, including humans, that invest very heavily in a single offspring can ill afford to have the effort made be wasted... So, because less fertile, we care for our kids, instead of scattering billions of human eggs in the sea and letting them take their chances with tuna fishing trawlers and ship traffic... the way baby porpoises and whales must, now...
This has been studied extensively in animals. I addition to what I said above, there is a flip side to living past menopause, as in time-to-puberty. It takes humans longer to reach puberty than most species have to live. Intuitively we can sense that if it takes a species a long time to reach puberty, then they need to live longer to survive.
One of the Star Trek series tried, largely failed I think, to broach that subject with the character Kes... who was a full grown "Ocampa"... two years old... with a full life expectancy of nine.
Given my choice, I'd try to avoid discussing this with Bill Gates or Prince Charles... or any of the other "we need to dramatically reduce the population to be more sustainable" crowd... improved over Hitler only because, hey, they're not as obvious in being racists... they basically want to kill everyone ?
Victims of our own success... means someone out there thinks you need to be a victim in more real terms ?
There is that parallel risk in the technology, too... that advancements in technology won't only contribute to greater longevity. I mean... we've had tortilla chips for as long as I have been alive, and I've eaten them for most of that time... but only in the last few years have technical advancements made them increasingly deadly... with the more recent introduction of new technology enabling squeezable sour cream packages.
I'm pretty sure that one innovation is shaving some number of years off my own longevity.
Consider an extreme example of insects vs humans. Insects mature fast and lay thousands of eggs. If they lived as long as humans, there would be no balance in nature. Humans on the other hand take at least 13 - 15 years to procreate (including the gestation time) and normally give birth to only one child at a time. A short lifespan would make us extinct.
Ahh... that gets back closer to what I was getting at... The population wide and social impacts aren't something you can ignore in relation to the genetics... in terms of the range of normal variation within the existing potential... which isn't "evolution" rather than acclimatization within existing potential as the times change. The time to puberty is strongly variable... with changes in the culture. It might be closer to 8 to 11 years in some situations... or more like late teens to early twenties in others. There's a longer term periodicity to it... with variations that synch with other things in parallel... like the swings between more or less religion in society... between higher or lower hem lines... also synched with the economy... boom times of the 20's saw changing social mores and clothing... that we were so far distant from in the 1950's... and have swung back to now in spades... I don't think the drivers are well characterized... but, "fast" times, or not, and "fat" times, or not, probably not the limit... social changes occurring rapidly... has impact... I suspect risk of survival has strong impact in relation... long and brutal wars probably changing those things, too ?
Not like you want to design an experimental situation just to study it... but, then, you don't have to...
Again brings up the parallel issue of how technology alters the cultural influences versus the genetic elements in the population level variations... Privacy and porn on computers... might well be an influence that alters that long period variation... disrupting some aspects of long term social cyclicallity ?
But this association has not been fully studied. We know that the more children you have (especially for women) the shorter the lifespan (all other factors being equal). The shortest "optimal" time between births for human female is ~3 years. *If* she is to have them before she is 30, then the theoretical maximum of births per woman is around 5 or 6 kids.
I'd have to study that one some more... some chicken or the egg issues inherent in it. Women having many more kids... ties in to the social cyclicallity issues... in which the probability of living less long is also strongly associated with the times you live in... no matter how many kids you have.
Technology again ? How much change results, today, from birth control options that didn't exist 100 years ago when women more routinely had larger numbers of children ?
Selective pressures ? The American frontier is an area of interest and study for me... the difficulties of life on the Oregon Trail... significant enough to impose real selective pressures... survivors were tough people...
Times aren't that hard now. People aren't that tough, either. We're not all cut out to be trailblazers... probably relatively few are... but those few ? How much impact on the rest of the population ? Portland (the original home of "being Shanghied") or San Francisco in 1845... or 1880... still probably dominated by those "tougher" types. Today ? Not so much ?
How true is that... and what does it mean for the survival of the species the next time the alien predators swing by to harvest a snack ? (I'm not really one of those who believes aliens put us here to farm us... sort of like sailors of old brought goats along on voyages of exploration... to off load them on random desert islands along the way... in the expectation that next time they passed by... there'd be a meal waiting for them.)
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