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Old Spleens Suck (2021)

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Re: Old Spleens Suck (2021)

#51

Post by majormajor »

ryeights wrote: post #12
resoluteteeth wrote: post #11

Earlier quoted context omitted.

The programmed aging theory may be "obvious" but there is not really evidence to support it as of the present. If true, it would likely be very easy to stop aging (there would likely be some mechanism in cells causing aging that could simply be switched off), but this has not been borne out by research so far, and this is despite the fact that much anti-aging researching assumes it to be true. The preponderance of th…

I don’t think it is at all necessarily true that there would be one mechanism for programmed aging that could be disabled by modern medicine. Rather, evolutionary pressures might cause many mechanisms to develop simultaneously to prevent aging of individuals too far beyond the point of reproductive viability. If aging is caused by built-up damage, how would babies ever come to exist and live normal lifespans? The cel…

I don't understand the proposed mechanism of evolutionary pressure here.

Evolutionary pressure can result in traits being selected over others because the individuals with the un-selected traits frequently fail to pass them on. But the cause and effect isn't so much "we need to survive this, let's devise an adaptation," it's "a certain trait happened to end up providing an advantage." There isn't an intentional aspect to the randomness of genetics.

Why and how would evolution - random mutation and selection pressures - penalize the long-lived? Many past cultures actually did the opposite, and elevated and respected elders, for their roles as knowledge holders and such. So how would being longer lived cause your progeny - who at that point would already be born - to be less prolific?

Re: Old Spleens Suck (2021)

#52

Post by xenadu02 »

majormajor wrote: post #51
ryeights wrote: post #12

Earlier quoted context omitted.

I don’t think it is at all necessarily true that there would be one mechanism for programmed aging that could be disabled by modern medicine. Rather, evolutionary pressures might cause many mechanisms to develop simultaneously to prevent aging of individuals too far beyond the point of reproductive viability. If aging is caused by built-up damage, how would babies ever come to exist and live normal lifespans? The cel…

I don't understand the proposed mechanism of evolutionary pressure here. Evolutionary pressure can result in traits being selected over others because the individuals with the un-selected traits frequently fail to pass them on . But the cause and effect isn't so much "we need to survive this, let's devise an adaptation," it's "a certain trait happened to end up providing an advantage." There isn't an intentional aspe…

If groups with many longer lived members suffered a disadvantage then natural selection would favor dying earlier, but not too early. You have to think about survival of genes in groups, not just individual survival.

FWIW my guess is it just didn't matter much. Surviving to 50 was plenty enough to have offspring yet not so long you compete with you grandkids for resources or become too much of a burden. That's already much much longer than most species so if anything evolution has already optimized humans to live fairly long lives. Once that got to be "long enough" there just wasn't enough selective pressure to matter.

Re: Old Spleens Suck (2021)

#53

Post by echelon »

outworlder wrote: post #44
echelon wrote: post #39

Earlier quoted context omitted.

Spleens are one of the more vulnerable organs. They're prone to rupture during trauma, and if ruptured, can easily cause a person to bleed out. In many motorcyclist accidents, a ruptured spleen can be the cause of death. Spleens are essentially large bags of blood and immunological pulp, and the reason they evolved this way is because they act as a filter against bloodborne pathogens. They host a diverse but speciali…

> You should read up on the thymus next. That one is super important and is also implicated in aging. That one seems to self-deactivate with age.

Indeed. The thymus is responsible for much of our immune cell production, but it shrivels away to nothing by our elderly years.

It's unfortunate, because our responses to immune challenges - including cancer - diminish with age.

Re: Old Spleens Suck (2021)

#54

Post by Hallucinaut »

sokoloff wrote: post #5
krisoft wrote: post #4

Earlier quoted context omitted.

What do you mean by “flight ejections”? Are we talking about ejection seat activations in military aircraft? This factoid sounds very suspect. Doesn’t most people who need to activate an ejection seat survive spleen or no spleen? Deaths may occur of course, an ejection is not without risks, but if everyone or nearly everyone with a spleen dies then my understanding of the risk associated with an ejection is seriously…

The risk of injury in ejection is quite a bit higher than most people expect (typically over 25% towards 50% for older tech ejection seats). It’s still a way better scenario than riding it in. It is not uncommon for an ejection to end a pilot’s tactical jet flying days for medical reasons.

Obviously if you're ejecting at or near supersonic speeds there are other stresses, but if the trauma is mainly from the ejection booster itself why is it still done with such force?

It seems like a majority of ejections shouldn't be benefited by half a second less time to achieve clearance (or the jet itself could detect altitude and adjust the speed to increase survivability).

I'm guessing this is also a function of trying to achieve lateral separation from the ensuing fireball in a crash but it surprises me rates are so high for injury.

Re: Old Spleens Suck (2021)

#55

Post by djmips »

gcanyon wrote: post #43
melissalobos wrote: post #37

Earlier quoted context omitted.

At least it was related to the decision to remove a spleen or not. In at least one case I now know of, in a young patient they decided to keep the spleen. In some cases hearing of unextraordinary events helps to calibrate what extraordinary is. I have never suffered a spleen injury, but have heard of lots of young men having theirs removed when I was younger. This anecdote leads me to believe those may have been extr…

Mine was lost due to rupture in a motorcycle accident. The doctors didn't say whether keeping it was an option, but I doubt it: it came with a bunch of broken ribs and two punctured/collapsed lungs, so my body had more than a few things to deal with, and fixing a spleen was probably low on the list.

Any issues as a result of being spleenless?

Re: Old Spleens Suck (2021)

#56

Post by TylerE »

Hallucinaut wrote: post #54
sokoloff wrote: post #5

Earlier quoted context omitted.

The risk of injury in ejection is quite a bit higher than most people expect (typically over 25% towards 50% for older tech ejection seats). It’s still a way better scenario than riding it in. It is not uncommon for an ejection to end a pilot’s tactical jet flying days for medical reasons.

Obviously if you're ejecting at or near supersonic speeds there are other stresses, but if the trauma is mainly from the ejection booster itself why is it still done with such force? It seems like a majority of ejections shouldn't be benefited by half a second less time to achieve clearance (or the jet itself could detect altitude and adjust the speed to increase survivability). I'm guessing this is also a function o…

Because you have to get up and over the tail of the airplane without it slicing you like a cleaver.

Re: Old Spleens Suck (2021)

#57

Post by GenerocUsername »

aklemm wrote: post #20

As an adolescent around 1990, I burst my spleen in the final minutes of a school ski trip. Nearly bled to death as the school staff transported me home and left me in my living room to be found later by my parents nearly unconscious. Anyway, I got to the emergency room that evening and there was much debate whether to remove my spleen. They decided not to and instead kept me hospitalized for 10 days and then out of s…

Hi! Nice to meet you! Similar story! I was on a university research trip in the Philippians when my spleen spontaneously ruptured. It took 4 days to get home and by the time I got back to States for diagnosis half my blood was in my belly area... I rejected surgery since it had been days since initial event and healed on my own...
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