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Ageing: The girls who never grow older

bbc.com

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Re: Ageing: The girls who never grow older

#11

Post by ars »

jostmey wrote: post #7
ars wrote: post #2

Summary: There are no conclusions or new research in this article. Talks about some theories of the scientist interviewed about what aging is (Spoiler: He doesn't know and all current theories have flaws), wastes some time on human interest fluff, gives an interesting picture of girls with Syndrome X (that prevents them from developing, in a way that might be a lack of aging - if you've already heard about it there i…

I actually thought this article did a pretty good job explaining why we age. As pointed out, our bodies fall apart because they are the product of an evolutionary process. Our genetic code is like a computer program that runs into a bunch of fatal errors after it has been left running for too long. These fatal errors do not matter to our genes provided enough time has elapsed since our birth for our DNA to pass on se…

Yes, that is one explanation, but it's refuted by other evidence. (And the article covers this.)

The main problem with the argument is that our body does a great job of fixing errors - so why does that process suddenly seem to stop? Why not just keep on fixing errors. If you can fix errors for 40 years why stop there? Why does the process suddenly stop at that age?

It's not like there is a gradual accumulation of errors - it's no errors for 40 years, then suddenly error correction mode is switched off. Why?

It also just raises the question of why there is a reproductive age in the first place? Why does that stop? (For women anyway - it doesn't seem to stop for men, so the evolutionary argument fails there too.)

But the biggest argument against that theory is other animals. Why do they have different lifespans? The genetic machinery for all mammals is more or less the same.

Re: Ageing: The girls who never grow older

#12

Post by withdavidli »

ars wrote: post #2

Summary: There are no conclusions or new research in this article. Talks about some theories of the scientist interviewed about what aging is (Spoiler: He doesn't know and all current theories have flaws), wastes some time on human interest fluff, gives an interesting picture of girls with Syndrome X (that prevents them from developing, in a way that might be a lack of aging - if you've already heard about it there i…

Wish I read this comment before reading that long article.

Re: Ageing: The girls who never grow older

#13

Post by drcode »

joe_the_user wrote: post #8

This is a new article on a condition that's been written about already. These are children who fail to reach maturity normally. All of this was evidence of what Walker dubbed “developmental disorganisation”. Brooke’s body seemed to be developing not as a coordinated unit, he wrote, but rather as a collection of individual, out-of-sync parts. “She is not simply ‘frozen in time’,” Walker wrote. “Her development is cont…

I really cringe at how this article takes some unfortunate people who are expected to die in early youth and sensationally spins it into "girls who have beaten aging".

Re: Ageing: The girls who never grow older

#14

Post by jostmey »

ars wrote: post #11
jostmey wrote: post #7

Earlier quoted context omitted.

I actually thought this article did a pretty good job explaining why we age. As pointed out, our bodies fall apart because they are the product of an evolutionary process. Our genetic code is like a computer program that runs into a bunch of fatal errors after it has been left running for too long. These fatal errors do not matter to our genes provided enough time has elapsed since our birth for our DNA to pass on se…

Yes, that is one explanation, but it's refuted by other evidence. (And the article covers this.) The main problem with the argument is that our body does a great job of fixing errors - so why does that process suddenly seem to stop? Why not just keep on fixing errors. If you can fix errors for 40 years why stop there? Why does the process suddenly stop at that age? It's not like there is a gradual accumulation of err…

First of all, there are a number of things that go wrong in our bodies as we age. Certainly genetic errors build up over time and are left uncorrected. But this is just one of many things that go wrong. The reason our bodies are allowed to degrade in the first place is because we have usually already survived well into our reproductive age.

The evolutionary theories of aging actually provide a pretty solid explanation as to why separate species have different lifespans. Some species take longer to reach reproductive maturity than others. Some species reproduce more slowly than others, which in turn effects how quickly the animal may age. Individuals in some species don't survive very long due to external pressures such as starvation and predation, which also shapes lifespan.

The best introduction into the evolutionary theories of aging I have found is: http://www.genetics.org/content/156/3/927.full.pdf . It is worth noting this theory explains human mortality curves once external causes of death have been removed.

Re: Ageing: The girls who never grow older

#16

Post by crystaln »

jostmey wrote: post #14
ars wrote: post #11

Earlier quoted context omitted.

Yes, that is one explanation, but it's refuted by other evidence. (And the article covers this.) The main problem with the argument is that our body does a great job of fixing errors - so why does that process suddenly seem to stop? Why not just keep on fixing errors. If you can fix errors for 40 years why stop there? Why does the process suddenly stop at that age? It's not like there is a gradual accumulation of err…

First of all, there are a number of things that go wrong in our bodies as we age. Certainly genetic errors build up over time and are left uncorrected. But this is just one of many things that go wrong. The reason our bodies are allowed to degrade in the first place is because we have usually already survived well into our reproductive age. The evolutionary theories of aging actually provide a pretty solid explanatio…

Would it not make more evolutionary sense to remain reproductively capable for hundreds or thousands of years?

The motive for genes to reproduce does not end after a single set of offspring. In fact, I don't think the motivation is even reduced.

Re: Ageing: The girls who never grow older

#17

Post by jostmey »

crystaln wrote: post #16
jostmey wrote: post #14

Earlier quoted context omitted.

First of all, there are a number of things that go wrong in our bodies as we age. Certainly genetic errors build up over time and are left uncorrected. But this is just one of many things that go wrong. The reason our bodies are allowed to degrade in the first place is because we have usually already survived well into our reproductive age. The evolutionary theories of aging actually provide a pretty solid explanatio…

Would it not make more evolutionary sense to remain reproductively capable for hundreds or thousands of years? The motive for genes to reproduce does not end after a single set of offspring. In fact, I don't think the motivation is even reduced.

The mathematics of life is exponential growth. Two begets four begets eight and so on. So if you happen to die from old age after the fifth or sixth generation, the effect on how many copies your genes make of themselves is marginal.

Re: Ageing: The girls who never grow older

#18

Post by SilasX »

crystaln wrote: post #16
jostmey wrote: post #14

Earlier quoted context omitted.

First of all, there are a number of things that go wrong in our bodies as we age. Certainly genetic errors build up over time and are left uncorrected. But this is just one of many things that go wrong. The reason our bodies are allowed to degrade in the first place is because we have usually already survived well into our reproductive age. The evolutionary theories of aging actually provide a pretty solid explanatio…

Would it not make more evolutionary sense to remain reproductively capable for hundreds or thousands of years? The motive for genes to reproduce does not end after a single set of offspring. In fact, I don't think the motivation is even reduced.

It's the standard problem of tradeoffs in evolution.

Strong is better than not strong. But a stronger model comes at its own fitness costs: maybe it requires more energy upkeep, maybe it sacrifices speed, etc. At some point, fitness benefit from additional strength is less than the fitness cost of the weakness it must accept.

Likewise, an infinitely-living, infinitely fertile organism is better (more fit) than a finite one. (The environmental cost is not a problem for those genes.) But the costs of having it eventually exceed the benefits: perhaps it requires a more robust replication process that's too energy-intensive.

OTOH, if somehow you could reduce this error rate that leads to aging without having to sacrifice in some other way, that would be a mystery.

Re: Ageing: The girls who never grow older

#19

Post by gone35 »

bnchdrff wrote: post #4
gejjaxxita wrote: post #3

Amazingly this can't be accessed from the UK, a bizarre consequence of the license fee: We're sorry but this site is not accessible from the UK as it is part of our international service and is not funded by the licence fee. It is run commercially by BBC Worldwide, a wholly-owned subsidiary of the BBC, the profits made from it go back to BBC programme-makers to help fund great new BBC programmes. You can find out mor…

BBC re-posted the article from this source: http://mosaicscience.com/story/arrested-development

Nice; that's a much better version. It includes references, for one.

For those interested, here is a non-paywalled version of the Walker 2009 paper that describes the case study [1].

[1] http://www4.utsouthwestern.edu/cellbio/shay-wright/publicati...

Re: Ageing: The girls who never grow older

#20

Post by ars »

jostmey wrote: post #17
crystaln wrote: post #16

Earlier quoted context omitted.

Would it not make more evolutionary sense to remain reproductively capable for hundreds or thousands of years? The motive for genes to reproduce does not end after a single set of offspring. In fact, I don't think the motivation is even reduced.

The mathematics of life is exponential growth. Two begets four begets eight and so on. So if you happen to die from old age after the fifth or sixth generation, the effect on how many copies your genes make of themselves is marginal.

You are completely forgetting that if the parent organism has extra copies so do all the children.

Compare 2^100 vs 3^100:

    2^100: 1267650600228229401496703205376
    3^100: 515377520732011331036461129765621272702107522001
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