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Coreen W

Darwin's missing thread

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;) Darwin has a missing thread.

One: All life loves to live.

Two: All life must necessarily, adapt towards a longer lifespan.

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Two: All life must necessarily, adapt towards a longer life span.

 

Not really. However, it was a paradox for evolutionary biology some time ago.

 

(1) Genotype (or organism, if you want) tend to increase their contribution to the growth of a population ®, it's natural selection (briefly).

 

(2) The main fitness components are; Survival, l(x), and Fecundity, m(x)

 

(3) Increasing l(x) = better survival = increase in fitness ®*

 

(4) Increasing m(x) = more offsprings = increase in fitness ®*

 

(5) Reproducing early is more important than reproducing late, because those offsprings start reproducing faster, so having offspring early contribute more to fitness than late.

 

(6) Solution ? ... antagonist pleiotropy !!! Some genes were shown to be beneficial early in life, but deleterious late in life.

 

(7) As having offsprings early is better for fitness than late, those antagonist genes increase fitness even if they decrease survival. Mathematical tools like those given by Charlesworth show that reducing survival late in life have nearly no effect on fitness.

 

(8) All life must not necessarily adapt towards a longer life span. :(

 

* All other things being equal...

 

If you are interested, I can give you the references for each of those point.

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One: All life loves to live.

 

I tentatively disagree, pending your definition of "love" in this context. "Love" seems to be an imprecise term here. I will assume that you mean that an organism has a "will to live". That is also questionable. For example, a virus or bacteria (if you consider it living) is simply a living machine, it has no will (that we can discern) and no emotions. I would venture that they lack the biochemistry to experience "emotion", in the normal sense of the word (this is certainly so for the human experience of emotion, which is largely biochemical, but many times triggered by external pressures, sometimes not).

 

For higher animals this might be true but again, I would ask you to more precisely define "love" in this context.

 

All life must necessarily, adapt towards a longer lifespan.

 

Once again, this is imprecise. I must assume for the moment that you mean that individual organisms (as oppossed to generations of them) must adapt towards a longer lifespan.

 

No, not necessarily. That would depend entirely on environmental pressures and the current state of adaptation to that environment. I can think of environments and states of the organism where it would be more advantageous to possess a shorter lifespan.

 

In fact, It seems logical to me that faster and multiple organism reproduction(i.e. generating thousands of offspring at once as opposed to a few) would enable a species to survive as well as or better than individuals possessing longer lifespans.

 

No, I don't believe that this is necessarily so. It might be so in some cases, but not in other cases. It depends simply on the lifeform, the environment and changes (i.e. Environmental pressures) that occur in either or both of those variables.

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The evolutionary advantages of a longer lifespan would probably be that an organism can survive different environmental changes and thus adapt better to any environment. For example, compare mammalian lives with the lives of flies, we can live in pretty much any environment regardless of the weather, whether it be cold, hot, tropical, humid, slightly acidic/basic, variations of sunlight intensity.

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Actually, the physiological tolerances of organisms are not related to lifespan. Rats live a lot longer than roaches, and both have wide tolerances. In fact, highly varaible environments would, IMHO, favor short lifespan; if you never know if the next drought or winter will kill you or not, it'd be best to invest in lots and lots of kids now and damn the consequences to your lifespan.

 

Mokele

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I am talking about Darwin's missing thread. I am not talking about whether I am right or not.

You don't seem to be "talking" about anything at all.

 

Give this thread a visible point.

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;) Darwin has a missing thread.

One: All life loves to live.

Two: All life must necessarily' date=' adapt towards a longer lifespan.[/quote']

Oh I love to love - but my baby just loves to dance, she wants to dance, she loves to dance, she’s got to dance. Oh I love to love - but my baby just loves to dance ......

 

Oh I love to love, but there’s no time for right romance no, no, no. Oh I love to love - but my baby just loves to dance.

 

The minute the band begins to swing it. She’s on her feet to dig it. And dance the night awaaaay.......

 

Stop! I’m spinning like a top. We’ll dance until we drop. But if I had my waaaaayyy.........

 

 

Oh I love to love - but my baby just loves to dance, she wants to dance, she loves to dance, she’s got to dance. Oh I love to love - but my baby just loves to dance. Oh I love to love, but she won’t give a love a chance no, no, no. Oh I love to love - but my baby just loves to dance

 

 

Stop! I’m spinning like a top. We’ll dance until we drop. But if I had my waaaaayyy.........

 

 

Stop! (Stop!) Instead of going Down Town. We’ll stay at home and get down

to what I try to say.

 

I love to love - but my baby just loves to dance, yeah, yeah

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You know... that's just went throught my mind when I read the first posting too!

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