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Telomere shortening rate predicts species life span

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Re: Telomere shortening rate predicts species life span

#21

Post by curious_one »

keenmaster wrote: post #14
Rch_East wrote: post #8

How do we slow our personal telomere shortening rate?

Other than being born with the right genes? Moderate exercise, like 30 min. of cardio 3 times a week, may help increase telomere length just as much as marathon running. Omega 3 and most things associated with a good diet also correlate with longer telomeres. A study showed that processed meat (like bologna with nitrate) has a negative effect on telomeres. Go figure. There is a very strong negative association betwee…

You can actually increase your telomeres? Is there a way to get them measured accurately?

Re: Telomere shortening rate predicts species life span

#22

Post by scotradamus »

scotradamus wrote: post #20
axaxs wrote: post #9

Earlier quoted context omitted.

I've seen this before and get the gist, but at face value, it's ridiculous. A human who runs every day may expend twice the heartbeats of a sedentary person. He or she will not live half as long, or anything close to it.

It's true, and the microscopic theory was done by the same physicist who found the macroscopic relationship, Geoffrey West (one of my personal heroes an current director of the Santa Fe Institute). The theory also explains the upper and lower bounds for the possible size of an animal. If you want to read about it he wrote an amazing book called Scale. I _highly_ recommend it.

OK, I'll add a bit to my previous comment. Is there a limit to how small a mammal can be? If so, what sets the scale?

TL;DR – effective pumping of blood requires precise allowable branching network of capillaries in the circulatory system. At a certain size this network goes from AC to DC and sets the scale for metabolic rate and lifespan in all animals with a circulatory system.

The scale is set by impendance matching of the circulatory system. The heart pumps blood. It is AC. To prevent the AC wave of blood from reflecting back when the capillaries branch out and get smaller, the branching network of the capillaries requires the cross-sectional area of the mother branch to be equal to the sum of the cross-sectional areas of the daughter branches. But when capillaries get too small the heart loses this AC advantage and goes from AC blood wave to purely DC.

So the smallest mammal a shrew has 2 capillary branches, 1 AC, 1 DC. Humans have 8 branches 6 AC then 2 like the shrew 1AC, 1 DC. A blue whale has 15 branches 7 AC then 8 like a human (6 AC then 2 like the shrew 1AC, 1 DC). This branching network sets the smallest length scale of a mammal (actually for any animal that uses blood and mitochondria as its metabolic energy source).

Going back, a shrew has 2 branches 1AC, 1DC. A shrew is 4cm in length and its heart must beat 20 times a second, as nearly all the hearts energy for all animals is expended to push blood through the last small DC branch portion of the capillaries. The shrew must be only 4cm and pump blood with the same pressure and speed as a human (which is the same speed and pressure as a blue whale) through the shrew’s tiny little heart. That is, smaller the animal the larger the metabolic rate. The larger the metabolic rate, the more wear and tear and repair on cells, the shorter the life span.

Re: Telomere shortening rate predicts species life span

#24

Post by keenmaster »

curious_one wrote: post #21
keenmaster wrote: post #14

Earlier quoted context omitted.

Other than being born with the right genes? Moderate exercise, like 30 min. of cardio 3 times a week, may help increase telomere length just as much as marathon running. Omega 3 and most things associated with a good diet also correlate with longer telomeres. A study showed that processed meat (like bologna with nitrate) has a negative effect on telomeres. Go figure. There is a very strong negative association betwee…

You can actually increase your telomeres? Is there a way to get them measured accurately?

Yes there are several companies that do this. TeloYears is one. They use a blood sample to index your telomere length (actual length) against other people your age (expected length). One of the outputs is a percentile rank for cellular age. While this can be useful information, there are a couple issues. One is that you can’t reliably predict expected lifespan simply using telomere length. The other is that it is over $100. You already know if you’re healthy and have good genes. I guess it could be used for benchmarking to see whether your telomeres are on the right track.

Re: Telomere shortening rate predicts species life span

#25

Post by aerique »

function_seven wrote: post #19
copperx wrote: post #16

Earlier quoted context omitted.

That's the assumption, but I have never seen or done the math either, which is ridiculous because it shouldn't take more than 5 minutes to get some estimates.

Okay, you shamed me into doing it :) So, this is really rough napkin math, but here goes: Assuming that... ... a sedentary person (Donald) has a resting BPM of 80. ... an active runner (Justin) has a resting BPM of 60, and a peak BPM of 180 (while running) If Justin runs for a solid 2 hours, five times a week, he will have 158*60*60 + 10*60*180 = 676,800 beats per week While Donald, who doesn't run, but averages 1 ho…

Just to be that guy: using two names very similar to eachother (especially for a non-native speaker) is very confusing for examples like this.

Re: Telomere shortening rate predicts species life span

#26

Post by inlined »

function_seven wrote: post #10
axaxs wrote: post #9

Earlier quoted context omitted.

I've seen this before and get the gist, but at face value, it's ridiculous. A human who runs every day may expend twice the heartbeats of a sedentary person. He or she will not live half as long, or anything close to it.

I think the idea is that a frequent runner will have a much lower resting pulse rate, and the “extra” beats they use while exercising will be more than offset by the fewer beats that accumulate during rest? I haven’t done the math though.

When I was a runner, I had a resting heart rate in the low 50s. While running I would hover at 180bpm. Now that I’m sedentary (knee accident) I have a heart rate in the 70s.

There are about 10k minutes per week and I ran for about 300 of them. That means my active lifestyle had about 588k beats per week and my sedentary lifestyle has about 750k beats per week. Sedentary life added about 27% total heart rate.

Re: Telomere shortening rate predicts species life span

#27

Post by function_seven »

aerique wrote: post #25
function_seven wrote: post #19

Earlier quoted context omitted.

Okay, you shamed me into doing it :) So, this is really rough napkin math, but here goes: Assuming that... ... a sedentary person (Donald) has a resting BPM of 80. ... an active runner (Justin) has a resting BPM of 60, and a peak BPM of 180 (while running) If Justin runs for a solid 2 hours, five times a week, he will have 158*60*60 + 10*60*180 = 676,800 beats per week While Donald, who doesn't run, but averages 1 ho…

Just to be that guy: using two names very similar to eachother (especially for a non-native speaker) is very confusing for examples like this.

Thanks. I actually confused myself when I was writing it. I should have taken that as a sign to change the names. (I was going for a reference[1], but that shouldn't muddle things!)

I hope the new names are differentiated enough.

[1] https://en.wikipedia.org/wiki/Dan_%26_Dave

Re: Telomere shortening rate predicts species life span

#28

Post by jayd16 »

jes5199 wrote: post #15

this makes me think that telomeres are not the main cause of aging-related death. My mental model is: if you run out of telomere before you get old, you start to get disease - and that’s maladaptive. So there’s evolutionary pressure to slow down your shortening rate, up to a point. Once it becomes unlikely that you’ll outlive your telomeres, there’s no more pressure. So your telomere length + rate becomes a measureme…

This doesn't really make sense does it? There's only really evolutionary pressure up to the end of your child rearing years, no?

Re: Telomere shortening rate predicts species life span

#29

Post by peter_retief »

The life span of a species can mean at least two things. The lifespan of individuals that belong to the species or how long the entire species can survive without mutating. I believe extinction, species lifespan and the theory of recapitulation (ontogeny recapitulates phylogeny) are intertwined https://en.wikipedia.org/wiki/Recapitulation_theory

Re: Telomere shortening rate predicts species life span

#30

Post by afthonos »

jayd16 wrote: post #28
jes5199 wrote: post #15

this makes me think that telomeres are not the main cause of aging-related death. My mental model is: if you run out of telomere before you get old, you start to get disease - and that’s maladaptive. So there’s evolutionary pressure to slow down your shortening rate, up to a point. Once it becomes unlikely that you’ll outlive your telomeres, there’s no more pressure. So your telomere length + rate becomes a measureme…

This doesn't really make sense does it? There's only really evolutionary pressure up to the end of your child rearing years, no?

Should be context dependent. New parents benefit a lot from their own elder family members giving them advice on the basics; in an environment with less information (i.e. no internet), the advantage vs. people with no parents or family to help would have been substantial. So unless we expand the definition of “child-rearing years”, I think it could go either way.
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