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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

#31

Post by thaumasiotes »

jostmey wrote: post #28
ars wrote: post #27

Earlier quoted context omitted.

> No, I am not. I assumed that the offspring will die of old age too. How does that change the conclusion? 3 children vs 2 is still immensely more children, not just a marginal amount as you thought.

When that third child is being born the second child is already beginning to reproduce (if you reproduce like Yeast). Clearly, that second child is more important because it has already given you a grandchild when your third child is still in the process of being born. That second child has already resulted into two offspring, and counts for twice as much.

> Clearly, that second child is more important because it has already given you a grandchild when your third child is still in the process of being born. That second child has already resulted into two offspring, and counts for twice as much.

Well, to pull the idea from my own other comment... a child+grandchild pair is not twice as good as a child even if all you care about is that specific moment in time). It's 1.5 times as good, because a grandchild is only half as good as a child.

And (as ars says) once all concerned have died, the timing offset is of no significance whatever. However, for the impact on your total representation in the world of the present (no particular present), which does have significance... see my other comment, where you're still quite wrong. The Euler-Lotka equation values all members of the population equally; that has no relationship to reality when you're talking about (in your own exact words) "how many copies your genes make of themselves".

Re: Ageing: The girls who never grow older

#32

Post by ableal »

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…

> this article should have waited for the results.

"Publish early, publish often" ? You know how the biz works ;-)

Not that, as a reader, I disagree. Thanks for the outline.

Re: Ageing: The girls who never grow older

#34

Post by chrisdone »

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…

I like how all the replies to your post are appealing to tradition.

“If you lived forever you'd starve people of resources and never evolve, that'd be bad!” If you lived forever, you wouldn't need to evolve, because you wouldn't be dying due to the environment. If you are still alive: you are well suited to be. Reproduction is just a form of genetic immortality if not individual immortality.

All of this presupposes that some immortal people were born and just died out because being immortal wouldn't be rewarded by reproducing.

And ignores the fact that animals that live for a very long time reproduce slower than animals that live for a short time.

Re: Ageing: The girls who never grow older

#36

Post by Houshalter »

deciplex wrote: post #21
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.

Think about it from the perspective of genetic material temporarily 'trapped' in the body like passengers on a boat. All else being equal, a new boat is better than an old boat. And, a new body is better than an old body (even if all the error correction machinery is there and fully working, a 26 year-old body has an advantage over a 46 year-old one, or an 86 year-old one). After the genetic material has been transfe…

No. Evolution selects based on relative fitness. Killing older members is obviously more efficient for the population as a whole. However individual genes that "defect" and continue reproducing into old age will make more copies and spread themselves more into the next generation than the "aging" genes. Even if it's inefficient and they use more resources (which isn't true, it takes a lot of effort and energy to raise a child, keeping an existing body is way better.)

Re: Ageing: The girls who never grow older

#37

Post by exratione »

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.

No:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjourna...

"Understanding why we age is a long-lived open problem in evolutionary biology. Aging is prejudicial to the individual, and evolutionary forces should prevent it, but many species show signs of senescence as individuals age. Here, I will propose a model for aging based on assumptions that are compatible with evolutionary theory: i) competition is between individuals; ii) there is some degree of locality, so quite often competition will be between parents and their progeny; iii) optimal conditions are not stationary, and mutation helps each species to keep competitive. When conditions change, a senescent species can drive immortal competitors to extinction. This counter-intuitive result arises from the pruning caused by the death of elder individuals. When there is change and mutation, each generation is slightly better adapted to the new conditions, but some older individuals survive by chance. Senescence can eliminate those from the genetic pool. Even though individual selection forces can sometimes win over group selection ones, it is not exactly the individual that is selected but its lineage. While senescence damages the individuals and has an evolutionary cost, it has a benefit of its own. It allows each lineage to adapt faster to changing conditions. We age because the world changes."

Re: Ageing: The girls who never grow older

#38

Post by owlmonkey »

Another researcher was sequencing Brook before she died, and I believe using the PacBio sequencer to get the full sequence (instead of an incomplete "whole" sequence using Illumina sequencers.) Hopefully something useful will emerge. Here is a link to a video of Brook on Katie Couric's show: http://katiecouric.com/features/is-there-a-way-to-slow-your-...

Re: Ageing: The girls who never grow older

#39

Post by deciplex »

Houshalter wrote: post #36
deciplex wrote: post #21

Earlier quoted context omitted.

Think about it from the perspective of genetic material temporarily 'trapped' in the body like passengers on a boat. All else being equal, a new boat is better than an old boat. And, a new body is better than an old body (even if all the error correction machinery is there and fully working, a 26 year-old body has an advantage over a 46 year-old one, or an 86 year-old one). After the genetic material has been transfe…

No. Evolution selects based on relative fitness. Killing older members is obviously more efficient for the population as a whole. However individual genes that "defect" and continue reproducing into old age will make more copies and spread themselves more into the next generation than the "aging" genes. Even if it's inefficient and they use more resources (which isn't true, it takes a lot of effort and energy to rais…

But, the genes are in the new body as well? So, wouldn't the genes that move to a new host and program the old host to expire be better off?

Re: Ageing: The girls who never grow older

#40

Post by VLM »

hrjet wrote: post #25
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.

A large life-span would starve the younger generations of resources. And the younger generations are probably more crucial to the survival of the gene pool, than the older generations for various reasons. One reason is that younger generations might be better adapted to the environment because of mutations. Another reason could be that the brains and bodies of older generations will eventually get saturated / tired.…

"Keeping them alive is inefficient for the species."

A lot of that is based on the idea of a nuclear American 1950s family, mom dad and 2.5 kids in a house and grannie lives in Florida 1000 miles away.

More likely, if I lived for 1000 years I'd spend a lot of time ensuring the economic success of my descendants by teaching programming, electronics, maybe math unless a better mathematician comes along. If this situation existed in the past, I have a GGGGG-uncle (cousin?) who was a Harvard literature prof in the early 1800s and I'm sure he would have taken a decade out of his semi-eternal life to educate me on English lit and related topics. I have some GGGG-Uncles who were in the civil war and fought in Tennessee, surely their personal experiences would have more impact than merely reading a book.

This has certain economic and evolutionary effects, such that a "migrant farm harvesting laborer" not allowed to ever benefit from his own labor, would not be able to help his GGGG-grandkids in any obvious way. So some kids are going to grow up with 16 hours a day of continuous one on one academic tutoring from a team of perhaps a dozen PHD ancestors, while other kids are going to grow up basically playing video games, or at best, watching youtube videos.

Its an obvious sci-fi topic to explore the nature vs nurture question. A permanent overclass would likely develop based solely on ancestry (indirectly "nature" although in practice "nurture")

This is aside from obvious social interaction. Locally I know a lot of the people in my field, and a descendent going into my line of work could be financially (aka reproductively) rewarded by hanging out with me and meeting people. If I do nothing for a descendent other than socially introduce them to local hiring managers, that's still genetically a net win. Everyone else will be doing the same thing so I will have to keep up.

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