Human Life Span & Evolution

i doubt DNA has anything to do with lifespan. Blind luck was the only thing giving any semblance of a long lifespan in those days when hygene was non existant and a common cold was a killer. Lifespan was the same, there are referances to individuals living to their eighties. But wether or not you reached the point where you'd die of age was not a good chance.as to the theories of nemesis...
if we can assume that dna did NOT affect changes in death rates, then it must not have changed. if so, the the previously mentionioned "genetic purity" could not have changed either.
On the matter of the vapor canopy, where exactly did it go? Nemesis says it helped hyper-oxygenate the earth, but there could not have been anything there that wasn't previously, and if so, then it has to still be there now. "no matter or energy can be created or destroyed", barring nuclear physics. On the same topic, a hyper-oxygenated earth would not do one whit against a virus or bacteria, or lack of hygene. The only thing the oxygen would do is poision all the plants in the world.

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I believe in God, I just call it Nature

Correct.The King list goes on for over 150,000 years with only the latter portion of the list having human kings.The rest were apparently from the 11th planet and functioned like managers for this plannet.They are similar to the Nephilim.Btw: Many happy returns of the day, Jar

Yes, improved sanitation and health care technology have resulted in the extension of human lifespan, but what are the evolutionary consequences?First, human lifespan is not, per se, subject to selection. What may be subject to selection is reproductive lifespan, as that can directly affect fitness. Any increase in the former could be merely a secondary consequence of selection acting on the latter.In animals, lifespan appears tightly linked to reproductive strategies. Lifespan is often negatively correlated with reproductive effort or positively correlated with onset of reproduction. For example, in the extreme case of semelparous organisms, reproduction results in death immediately.So we can ask the following questions:1. Are we reproducing less? (that should, in theory, help us live longer). The answer is largely 'yes' in developed countries and 'no' in undeveloped countries, so such a correlation does appear consistent, but does not necessarily imply any causation.2. Are we reproducing later in life? (in theory, this can also lead to longer lifespans under situations where more resources must be garnered before initiating reproduction in porder for it to be successful). Again, the answer is generally 'yes' in developed countries, and 'no' in underdeveloped countries, so the corrlation between reproductive strategy and longevity holds again.So we consider that the developed countries have most of the technology and sanitation to extend not only human life, but human reproductive lifespan. This has lead to consequences quite consistent with evolutionary theory - delayed onset of reproduction (possible because of reduced risk of dying prior to having any offspring) and reduced numbers of offspring (possible because the chances of survival of each are greatly improved).
These trends are not evident in the developing world because lifespan is still substantially shorter there and consequently there is still strong selection for early reproduction and higher fecundity in those environments.The conclusion? If we could improve health care, sanitation and human longevity in the developing countries, the effect would be to reduce their population explosion problem because we would be relaxing selection for early onset of reproduction and high individual fecundity.

But these fellas failed to follow God's command. They were given all these years but only had a couple of kids. If I was given all that time I would start a country.... watch out China!!!

As usual, EZ, thank you for complicating my understanding.I wonder what you think about two other factors: the earlier onset of menarche in developed nations (usually attributed to improved nutrition, I believe) and the widespread use of contraceptivesWould not the earlier onset of menarche in the developed regions off-set the effects of otherwise delayed reproduction? We certainly see earlier reproduction in our own, "internal" less (economically) developed areas than we do in more affluent communities...I think.Doesn't the use of contraceptives to delay reprodution blur the selection effect, since the phenomenon is driven by chemical means rather than genetic ones? If the later-breeding orgamism is selected for, yet is breeding later without any correlation to genetic endowment, what is being selected?I'm all questions here, and I suspect I'm not seeing the matter clearly.

Yes, I have pondered this phenomenon.
I would speculate that 'potential reproductive lifespan' has probably been decoupled from 'actualized reproductive lifespan' in humans, especially in the developed world where contraception is readily available.
In other words, the availability of contraception, both male and female-based, may effectively counter what would otherwise be a trend toward earlier onset of reproduction associated with earlier onset of menarche. Also we have cultural factors - teenage pregancy is obviously heavily stigmatized in most modern (although not in many primitive) societies. I would not expect so. If anything, it could facilitate it.
In other words, humans in developed countries can now voluntarily choose to delay onset of reproduction beyond the limits otherwise determined by biology. The question is why they would choose to do so (i.e. why such behavior should be selected). So this sort of approaches your other question: The behavior. And although human behavior has a degree of heritability, it is also strongly affected by cultural selection independently of genetics. Quantity of surviving offspring is far too simple a definition of fitness for humans, regardless of its value in application to plants and other animals. Humans are probably more selected to maximize offspring 'quality' and this can be socially determined. The structure of human society redefines fitness for its own species. I suspect there are strong social and cultural benefits to individuals of delayed reproduction and reduced fecundity. The reduced financial burden is an obvious one. Many people delay having kids until they feel financially secure, and this typically comes later in life than reproductive maturity. (I waited until I was over forty - and I still didn't feel financially secure enough )These same 'socially-influenced reproductive strategies' are not functionally advantageous in generally impoverished countries, so we don't observe the same consequences for human demography.Although I am sure this explanation can be improved on, I think it is basically consistent with the evidence at hand. But feel free to tear it apart...

Not me, EZ. I appreciate the enlightening comments. I am particularly pleased to see: I often feel exasperated when I read analyses that treat humans like pea plants, as though behavioral elements were neither inheritable nor mediated by culture. I find your outline both fascinating and satisfying. Thanks again.

Genesis 6:3 KJV "That the sons of God saw the daughters of men that they were fair; and they took them wives of all which they chose. And the LORD said, My spirit shall not always strive with man, for that he also is flesh: yet his days shall be an hundred and twenty years."Just thought you might want some scripture on the topic.Funnily enough, Moses is believed to have been born around the middle of the 14th century BCE, and died sometime in the 13th century BCE, with an estimated life of 120 years. Genesis is dated in the 14th century BCE so he wrote it a long time before his death and i dont think he was referring to himself in this verse. The physical ends (tips) of each chromosome are named telomeres and after each replication of out DNA these ends shorten. These telomeres protect and stabalise our DNA sequence and as they shorten (with age/replication) the DNA becomes more prone to things such as cancer etc. From this it has been estimated that the maximum (although different depending on individual) age that one can live to is 124 years. I have no idea if this is valid or not, i just read it somewhere (google it- try telomeres).Yes I also realise that this does also provide evidence against the 900 year old figures in the bible. But you must take into account that the people in the bible are based around a miracle working, all powerful God who is not bound by these minor issues .Matt

I've heard similar, and that was always my understanding as to why human life was limited. The problem is that this is in direct conflict with the Bible.What can the Bible-believers say? Why did God suddenly decide to not let people live so long? In my opinion, it was just added by the writers so they could explain why we don't live that long.All the scientific explanations seem to do me fine... it's the Biblical one that doesn't make any sense.Trék

Well I did try to answer that in the scripture in my last post. Here is a translation thats a bit easier to understand.Genesis 6:1-3 NLT "When the human population began to grow rapidly on the earth, the sons of God saw the beautiful women of the human race and took any they wanted as their wives. Then the LORD said, "My Spirit will not put up with humans for such a long time, for they are only mortal flesh. In the future, they will live no more than 120 years."However every other translation I have read does not tranlate it as "will live no more than 120 years" but as "his days shall be an hundred and twenty years." or something to that effect.From the translation I gather that the age drop is a punishment to man for sexual sin e.g. taking many wives. This is just from what I can gather. Genesis was written by Moses. He is not a liar and would not have said "Then the LORD said" if he was just making up an explanation.I know in your previous posts you did say about not mentioning the fall. I dont think it was the fall specifically because the life spans only started getting shorter quite a while after Adam. The bible does tell us however that sin causes death. A Biblical explanation could be that as the people of the world became more corrupt and disobedient to God. Then earlier death was a natural result. The belief is held by many christians that the only reason we die is because of sin. If Jesus had continued to live a sinless life he could have lived forever, same with Adam. Man was initially created to live forever, we only die because of sin.John 10:18 NLT "No one can take my life from me. I lay down my life voluntarily. For I have the right to lay it down when I want to and also the power to take it again." - JesusI know I am saying some things as true statememnts not as "The bible teaches that". ( e.g. we only die because of sin.) This is just to save time. Most of what I have said just trying to show how it is understood biblically.You cant try to explain the lives of biblical people if you dont believe in God. Its like trying to believe Moses parted the Red Sea without believing in God. Im just trying to explain how some christians understand it.Hope I have helped.Matt

Matt, we are over on the science side of the board now. It's fine to mention that you happen to believe in some of the things you posted, like that Moses wrote Genesis or the Bible mentions folk living 120 years, but over here you really need some evidence.The Bible, the Epic of Gilgamesh, Rip van Winkle, Ask and Empla and other myths are anecdotal evidence but nothing more. We need something that can be tested. If you believe that folk did live longer at some time, you need to bring forward your evidence in support.

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I am not really sure of how I could answer this scientifically or in a way that could be tested. I was just attempting to answer his question as to how it is explained biblically.Im not saying people in the bible lived 120 years, people live 120 years today. We are discussing the claims in the bible that some people lived up to 900 years etc. Im not really aware of any other sources besides the bible that records the people he was asking about living this long, so thats all I have to go on.I dont think he was asking for a scientifical explanation, he was more asking what bible believers think. Maybe im wrong.Thanks.matt

Precisely. I am trying to grasp this one. There isn't any physical evidence of longer-living people in the past. All the evidence seems to show that people lived longer in the past. So, if more sin = shorter lives, than why do Christians claim the world is so full of sin, yet lifespans are continuing to increase?Like Jar said, evidence evidence evidence... that's what it's all about. A little Bible scripture is perfectly fine with me as long as you put up enough evidence to support it.Trék

Yeah, sort of, but I'm also interested in hearing the evidence behind the claims.Trék

Okay then, sorry. I misunderstood what you were after. Not to sure on that. But obviously its not a strict equation as in how much you sin will determine your lifetime. Because obviously there are people who live very sinful but yet very long lives and vice versa. I was just throwing some ideas out there.Sorry about my lack of evidence. I suppose the scripture from Genesis I gave is about it . Umm... What???ThanksMatt