Ageing: The girls who never grow older • Hacker News Board

Re: Ageing: The girls who never grow older

#41

Post by bjeanes » Wed, May 21, 2014, 5:02 PM UTC

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…

> 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?

Because then you compete for resources with your offspring and limit the chances of passing on your genetic code.

Re: Ageing: The girls who never grow older

#42

Post by SilasX » Wed, May 21, 2014, 5:18 PM UTC

exratione wrote: post #37

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.

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 bet…

>drive immortal competitors to extinction.

That's something I wouldn't want to be quoted on. :-P

Seriously though, it's making a group selection argument, which stacks the deck against it: any gene that weeds out the host for the benefit of the "generation" will be strongly selected against.

Re: Ageing: The girls who never grow older

#43

Post by emiliobumachar » Wed, May 21, 2014, 11:50 PM UTC

deciplex wrote: post #39

Houshalter wrote: post #36

Earlier quoted context omitted.

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?

Genes do not move, they replicate. The old host did not lose the genes when reproducing.

Re: Ageing: The girls who never grow older

#44

Post by arkj » Thu, May 22, 2014, 6:24 AM UTC

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…

I think the question really is, if the inbuilt mechanisms are working efficiently, why should there be a difference between 46 year old vs 26 year old. I the replenishment of the cells go intact why should it matter how old one is, unless there is something inhering in the genetic material itself that is time bound.