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 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.
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."
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.
I think there is a case to be made that death gives organisms, that is to say it gives genetic material (which is the important bit, not the organism which is a mere vessel for the genes) an evolutionary advantage.
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.
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.
Compare 2^100 vs 3^100:
2^100: 1267650600228229401496703205376
3^100: 515377520732011331036461129765621272702107522001You neglected the variable of time. That third offspring will be born after the second one, which is born after the first one. You need to use the Euler-Lotka equation. The mathematics was worked out centuries ago. Here is the wikipedia article
How does that change the conclusion? 3 children vs 2 is still immensely more children, not just a marginal amount as you thought.
> That second child has already resulted into two offspring, and counts for twice as much.
Only for one generation, but we care about many many generations. 10 generation down the line the slight difference in timing makes no difference.
But the increase in number made an enormous difference.
You really need to sit and run some numbers and you'll see you are mistaken.
Maybe your intuition will help you if think of it as a steady state - babies in (born), babies out (die), rather than thinking about one moment in time. In a steady state the timing make no difference (because you've already waited out the time) - only the number matters.
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".