Evolution

[Woolygimp]

The mutation and replication of DNA and evolution as we know it is inherently as stupid as a rock because it's a non-intelligent entity. I look at it like a gutter is to water, as in it coerces the path in which water is to travel.

However, if it was merely survival of the species as the primary motivation for evolution why wouldn't our DNA conform in a manner to ensure the longest longevity of a given species? Species have a certain time clock involved for life expectancy as a fly can only live for days or weeks, while humans cannot live past 120-something (forgot the exact age). There are creatures with far more longevity than the average human, so evolution is definitely capable of longer lifespans but why does it settle for less in so many cases when it's counterproductive.

Another thing I was wondering about is whether or not there was an inherent random factor involved.
The first macro-evolution yielded dinosaurs, then they died out and we were supposedly the result on the second-go?

So assuming you have another planet in another galaxy with the exact same conditions as Earth, would dinosaurs be the result...or even humans? When I say conditions, I'm including oxygen levels, atmosphere, gravity, terrain composition, and natural disasters including the one that wiped out the dinosaurs.

[CallMeIshmael]

dying is evolutionarily superior to not dying

(by "dying" I mean the process of aging towards death)

[vhawk01]

[ QUOTE ]
The mutation and replication of DNA and evolution as we know it is inherently as stupid as a rock because it's a non-intelligent entity. I look at it like a gutter is to water, as in it coerces the path in which water is to travel.

However, if it was merely survival of the species as the primary motivation for evolution why wouldn't our DNA conform in a manner to ensure the longest longevity of a given species? Species have a certain time clock involved for life expectancy as a fly can only live for days or weeks, while humans cannot live past 120-something (forgot the exact age). There are creatures with far more longevity than the average human, so evolution is definitely capable of longer lifespans but why does it settle for less in so many cases when it's counterproductive.

Another thing I was wondering about is whether or not there was an inherent random factor involved.
The first macro-evolution yielded dinosaurs, then they died out and we were supposedly the result on the second-go?

So assuming you have another planet in another galaxy with the exact same conditions as Earth, would dinosaurs be the result...or even humans? When I say conditions, I'm including oxygen levels, atmosphere, gravity, terrain composition, and natural disasters including the one that wiped out the dinosaurs.

[/ QUOTE ]

Dinosaurs were nowhere near the first macroevolution, they are far closer to "most recent" than first. Also, evolution is not geared towards the survival of the species, it is geared toward the survival of the individual, and more specifically, the individual gene IN the individual. This is very often at the EXPENSE of the species, as it is almost always the case that your biggest competitors are your fellow humans, dinosaurs, birds, etc.

I'm not really sure what any of that has to do with the life expectancy question, just clearing up a few misconceptions. However, the life expectancy question is an interesting one, and I'm not positive there is a universally accepted and understood answer. We've had threads on it in the past, with regards to both humans and other animals. It does seem very much as if many animals are programmed to die at a very specific age, and it is impossible to tell for sure if humans are among them. Some evidence that points towards it is the fact that the maximum life expectancy hasn't really ever risen, as far as we can tell. This might just be an 'actuarial escape velocity' type problem, or it might be a genetically determined self-destruct sequence. I can hypothesize a few explanations for this, but I'm not sure what the data says.

[vhawk01]

[ QUOTE ]
dying is evolutionarily superior to not dying

(by "dying" I mean the process of aging towards death)

[/ QUOTE ]

I don't know why thats obviously true, except for the "if it happens, it was selected for at some point" argument, which isn't convincing in this case. It makes sense that sticking around and hogging all the resources while you were no longer reproducing is a giant waste, but I think this just raises more questions than it answers. Why do we only reproduce for a set number of years? Because our gametes have a shelf-life. Why do we even live as long as we do? Because humans are born very undeveloped, due to limitations on head size vs. pelvis width. This necessitates a longer juvenile stage, which means adults need to live longer, and so on.

Another objection: some species are, for all intents and purposes, immortal.

[CallMeIshmael]

[ QUOTE ]
[ QUOTE ]
dying is evolutionarily superior to not dying

(by "dying" I mean the process of aging towards death)

[/ QUOTE ]

I don't know why thats obviously true, except for the "if it happens, it was selected for at some point" argument

[/ QUOTE ]

Ill look around to see if I can get a copy of the work somewhere for free, but it was covered in this book:

http://www.amazon.com/Dynamic-Models-Bio...0277&sr=8-1 (http://www.amazon.com/Dynamic-Models-Biology-Stephen-Ellner/dp/0691125899/ref=sr_1_1/102-4890046-0457740?ie=UTF8&s=books&qid=1181520277&sr=8-1)

There is a very convincing model showing senescence is evolutionarily favourable

[ruken]

Looking at the dinosaurs and then humans as the two main byproducts of evolution is extraordinarily narrow and misses an enormous animal kingdom underneath in both instances, most of which we have little to no knowledge about.

Evolution is not really a process in the real sense - it's a by-product of massive numbers of organisms having statistically better or worse opportunity to reproduce. Any variation that results in improving a particular organism's chances to attract a mate and reproduce is going to be generationally favored over standard configurations (re: larger feathers on a peacock, for instance), thus shifting the curve for the entire species on the whole. Over time this can result in significant changes.

Short-lived species exist not because they are evolutionarily deficient, but simply because their life cycle model works for them. They still successfully reproduce and carry on their lineage and their species survives, so whether they live long or not is moot.

Cliff notes: Survival is not the goal. Reproduction is.

[FNG]

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However, if it was merely survival of the species as the primary motivation for evolution

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Gotta stop you right there.

First, evolution has NO motivation whatsoever. DNA reproduces imperfectly. Evolution emerges from this process.

Second, this should answer the rest of your questions, too.

[SNOWBALL]

we're just DNA vessels. Our genes couldn't give two [censored] about how long we live, as long as we breed, and our genes don't care how long our progeny live, as long as they breed, and so on and so forth. Replication is the only thing that matters for genes. It just so happens that human babies are so weak and stupid they they need parents to live for a while to take care of the baby. Similarly, Grandparents can be useful to impart wisdom. Everyone is just an appurtenance to the future generations though.

[Paragon]

Hypothetically, if all humans cooperated, we could increase our average/maximum lifespan, assuming we had enough time on an evolutionary scale. All you have to do is set a minimum age before being allowed to reproduce. Starting at 20 would already be pretty high. Gradually, after a few (hundred?) generations, start raising the bar to 21, 22, and upwards all the way to 50 if you like. Genes that were advantageous for long individual lifespans would quickly come to dominate. I'm guessing the ceiling could be raised pretty high...

[MidGe]

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First, evolution has NO motivation whatsoever.

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A very hard to understand but key element to understand if you want to have any meaningful discussion about evolution theory.

[soon2bepro]

[ QUOTE ]
Hypothetically, if all humans cooperated, we could increase our average/maximum lifespan, assuming we had enough time on an evolutionary scale. All you have to do is set a minimum age before being allowed to reproduce. Starting at 20 would already be pretty high. Gradually, after a few (hundred?) generations, start raising the bar to 21, 22, and upwards all the way to 50 if you like. Genes that were advantageous for long individual lifespans would quickly come to dominate. I'm guessing the ceiling could be raised pretty high...

[/ QUOTE ]

Do you really consider us ignorant and powerless enough to have to depend on natural evolution?

[Siegmund]

I consider us ignorant enough, and obsessed enough with our own power, to think we can do whatever the heck we want and completely ignore the consequences of natural evolution. It does still operate, and it will come around to bite us in the ass from time to time.

For instance - bringing into general use drugs which are moderately effective against a virus, is a great way to create a more powerful virus, not a great way to tame a disease. Might be better to wait until an efficient sledgehammer is developed.

For a couple more instances that operate on longer time scales - going so far out of our way to help infertile couples conceive and help sickly/premature babies survive may or may not have some interesting consequences in the future.
One thing that I AM sure is going to have severe consequences in the future is the popularity of c-sections. There are all sorts of survival advantages to having large babies, and average birth weight has already risen rapidly in the past hundred years... I think we could VERY easily get ourselves into a situation within a thousand years where it's virtually impossible for women to survive natural childbirth. "Give birth by surgery only" strikes me as a pretty serious evolutionary mis-step.