It's very likely that aging is driven by some kind of scheduled gene program. It makes perfect sense to phase out individuals from a group-level selection point of view.
Perhaps not a phase-out program, but a progressive shut-down program, as a trade off between peak performance and total lifespan, where the characteristic patterns of ageing is what allowed humans to live much longer than other animals around the same size. Similar to the idea in this comic: https://www.badspacecomics.com/post/the-suit
By this logic, as a hedge against sudden death around ~50, the human body start cranking down the output of its diverse subsystems by then, to maximize operacional life, just like NASA engineers from time to time turn off instruments in the voyager to keep it operational against the odds. This is what we call ageing.
I think this argument only makes sense on the surface level. If it was the case that humans hit some hard limit to growth (perhaps running out of 'room' to grow, or losing the ability to process new energy, etc), then I think it could make sense to do this sort of 'graceful decommissioning' behavior, which we'd come to know as aging. But is there a hard limit we hit, aside from the aging process itself? None is obvious to me.
What limitation is our body pushing off by 'choosing' to age, instead of continuing as normal?
Edit: Regardless of the validity of the argument, I loved that comic, thanks for sharing.
Maybe. But why in this case do we not see bugs and failures in this program, i.e. no one lived 5 times more than the average or did not live forever at all, for example? I'm not making a statement, just a guess.
Lots of models could explain this. For example, let's say it's not just one program, but thousand of programs running in your body, trying to get you to age or die. The chances that all of them bug out would be astronomically low.
Because the whole system is quite resilient and self-repairing, and probably requires a great deal of consistency between the various genes? Aging is quite fundamental to life, and a "bug" in that area would almost certainly cause severe problems in other areas, probably death. Cancer might be an example. And systems of many components tend to narrow the standard deviation of the composite.
But that's just guessing. The article might not even have found something profound, but a life-style effect. On the one hand, we're living long (historically speaking), on the other hand, we have unnatural habits.
Such arguments go both ways. For example, if aging is accumulation of damage and not programmed, then why don't we see lucky people who live 5 times longer. Also how come the patterns of aging are so similar between individuals and even between different species (wrinkly skin, grey hair, fragile bones).
Because the odds of something 5x the average that's more or less normally distributed are really, really low.
It's the same as how although you can occasionally get a "natural" person over seven feet tall, it's very rare. Most really tall people have gigantism or some other form of pituitary abnormality, and I believe every recorded person to break eight feet has had such an abnormality.
It's like asking why we've never had someone with 500 IQ. There's a hard limit where anyone with enough of a mutation to enable that would probably also not survive long at all. And indeed with the height thing we see a lot of super-tall people dying younger due to cardiovascular strain and other issues. You get the picture.
This would be an optimistic scenario and introduce a possibility for the "scheduled gene program" to be controlled or turned off. The current thinking in the field seems to favour the idea that aging is a complex combination of programmed changes, stochastic damage, as well as various adaptations to help cope with the damage.
Depends what you mean by "group-level". A large part of Dawkins was pointing out that many of your individual genes had a very large stake in wanting your nieces and nephews to survive, as there was a high probability those genes were also present in the niece and nephew.
Which is actually a pretty good reason for something like menopause to get programmed in. A proto-human capable of getting pregnant into her 60s would produce more offspring, but if accumulated damage meant they (and she) rarely survived the pregnancy, that could be less beneficial to the family group (including numerous relatives other than direct descendants) on average than having her switch the capability off and live another generation (but not many more generations, because then there's a lot of infertile people competing for food, and your tribe only needs so much accumulated wisdom)
Intuitively it seems like a logical selection to happen though. One of the reasons why all of the hierarchies have evolved, why some are leaders, why some are inventor minded, and why most people are like most people.
My hypothesis is that it's just the continuation of the development program that starts with conception. It just turns self-destructive at some point, because natural selection didn't do anything about that because when humans were living in caves, no one lived to these kinds of ages anyway.
So, to rejuvenate the body, you would have to find where the current state of that program is stored, and overwrite it to a younger one, as if using a debugger. So far there are two promising developments about that: Michael Levin's research about bioelectricity, and Harold Katcher's research about exosomes (he seems to have abandoned it, but other people are picking up).
Yes it is: "Group selection, which was once widely rejected as a significant evolutionary force, is now accepted by all who seriously study the subject." (https://pmc.ncbi.nlm.nih.gov/articles/PMC3110649/)
Life expectancy much longer than 40 is a modern thing for humans though. So where would the over 40s schedule have come from? Or do you mean the schedule basically says: once you hit 50 start falling apart?
No, it’s not a modern thing, you’re conflating average life expectancy at birth with how long people lived in general.
> Back in 1994 a study looked at every man entered into the Oxford Classical Dictionary who lived in ancient Greece or Rome. Their ages of death were compared to men listed in the more recent Chambers Biographical Dictionary.
Of 397 ancients in total, 99 died violently by murder, suicide or in battle. Of the remaining 298, those born before 100BC lived to a median age of 72 years. Those born after 100BC lived to a median age of 66. (The authors speculate that the prevalence of dangerous lead plumbing may have led to this apparent shortening of life).
Life expectancy in the past was heavily depressed by high child and maternal mortality. For those who survived into adulthood (say, 20), dying in one's 30s or 40s was not the norm. Most lived into at least their 50s, and many reached their 60s or beyond. Hard labor and disease made very old age rarer than today, but old age itself is not a modern phenomenon. Skeletal remains and records confirm its presence throughout history.
The average life expectancy was low because of more deaths during childhood and wars. But the natural lifespan was more or less the same as it is today. For example, take a look at famous philosophers or politicians from Ancient Greece. Majority of them lived to about 70-80 years of age.
People keep repeating this, but my understanding is that low overall life expectancies historically were substantially about high infant mortality. If you made it out of childhood, your chances of living to be "old" were decent. It's not that the program used to say to start decaying at 40, it's that other exogenous forces would stop a lot of people from getting to that part of the program.
Qem|7 months ago
By this logic, as a hedge against sudden death around ~50, the human body start cranking down the output of its diverse subsystems by then, to maximize operacional life, just like NASA engineers from time to time turn off instruments in the voyager to keep it operational against the odds. This is what we call ageing.
pinkmuffinere|7 months ago
What limitation is our body pushing off by 'choosing' to age, instead of continuing as normal?
Edit: Regardless of the validity of the argument, I loved that comic, thanks for sharing.
rootingforroots|7 months ago
NoOn3|7 months ago
hyperman1|7 months ago
https://en.m.wikipedia.org/wiki/Henrietta_Lacks
csallen|7 months ago
tgv|7 months ago
But that's just guessing. The article might not even have found something profound, but a life-style effect. On the one hand, we're living long (historically speaking), on the other hand, we have unnatural habits.
piombisallow|7 months ago
kkoncevicius|7 months ago
0xcafefood|7 months ago
landl0rd|7 months ago
It's the same as how although you can occasionally get a "natural" person over seven feet tall, it's very rare. Most really tall people have gigantism or some other form of pituitary abnormality, and I believe every recorded person to break eight feet has had such an abnormality.
It's like asking why we've never had someone with 500 IQ. There's a hard limit where anyone with enough of a mutation to enable that would probably also not survive long at all. And indeed with the height thing we see a lot of super-tall people dying younger due to cardiovascular strain and other issues. You get the picture.
oneshtein|7 months ago
kkoncevicius|7 months ago
piombisallow|7 months ago
munchler|7 months ago
notahacker|7 months ago
Which is actually a pretty good reason for something like menopause to get programmed in. A proto-human capable of getting pregnant into her 60s would produce more offspring, but if accumulated damage meant they (and she) rarely survived the pregnancy, that could be less beneficial to the family group (including numerous relatives other than direct descendants) on average than having her switch the capability off and live another generation (but not many more generations, because then there's a lot of infertile people competing for food, and your tribe only needs so much accumulated wisdom)
mewpmewp2|7 months ago
piombisallow|7 months ago
grishka|7 months ago
So, to rejuvenate the body, you would have to find where the current state of that program is stored, and overwrite it to a younger one, as if using a debugger. So far there are two promising developments about that: Michael Levin's research about bioelectricity, and Harold Katcher's research about exosomes (he seems to have abandoned it, but other people are picking up).
petters|7 months ago
piombisallow|7 months ago
jebarker|7 months ago
adamors|7 months ago
> Back in 1994 a study looked at every man entered into the Oxford Classical Dictionary who lived in ancient Greece or Rome. Their ages of death were compared to men listed in the more recent Chambers Biographical Dictionary. Of 397 ancients in total, 99 died violently by murder, suicide or in battle. Of the remaining 298, those born before 100BC lived to a median age of 72 years. Those born after 100BC lived to a median age of 66. (The authors speculate that the prevalence of dangerous lead plumbing may have led to this apparent shortening of life).
https://www.bbc.com/future/article/20181002-how-long-did-anc...
Just one source
barrkel|7 months ago
kkoncevicius|7 months ago
dyauspitr|7 months ago
abeppu|7 months ago