Human Life Span & Evolution

Just realised that the lifespan increase could be attributed to advances in medicine and diet etc, which were not available to previous generations.Matt

Hey mate, don't think people are are out get you on this, it's just that in the science forums empirical evidence is the only currency!Edited by RickJB, : No reason given.

What? People are all fundementally the same, so of course you can. You can say "jesus went to the bathroom because he had eaten" and youve explained a part of his life. Just cant give a theory and say "you wouldn't understand, you're not christian" because then theres something fundementally wrong with the theory...

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-I believe in God, I just call it Nature
-One man with an imaginary friend is insane. a Million men with an imaginary friend is a religion.
-People must often be reminded that the bible did not arrive as a fax from heaven; it was written by men.

Average age span by species has been increasing, although it is hard to get real numbers to work with.Certainly the historical record is only good for the last 4000 years or so, which is fairly insignificant within the 160,000 to 200,000 span for Homo sap (~2 to 3%), and beyond that one needs to look at the fossil record.What we end up doing is comparing average ages of all fossils within a {species\time period} group. This is relatively unsatisfactory due to sampling error issues.One interesting thing is that apparently life span was greater for {hunter\gatherers} before agriculture than it was for the average human in the early agricultural dynasties.Of course this was when hunting technology had become fully developed, and earlier {H\G} populations had shorter lives.It is always interesting to find fossils of relatively old people in ancient fossil groups, evidence of care for the elderly, people with no or very bad teeth and physical deformities, a cultural plus.I used to have a link for life spans for hominids, but it is broken now. Lucy was 25 or so.Enjoy.

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RebelAAmerican.Zen[Deist
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Fair enough, but my point was that in evolutionay terms its doesnt make sense to believe that people could have at one stage lived 900 years. Maybe it does, but why would our life spans have decreased so drastically. Surely long life is an advantage.Matt

Precisely my point! Why do Believers insist on it being so without the evidence? I mean, even puting evolution aside for a second, 900-year spans don't make sense! Only if you're able to reproduce during that extra-long span. If not, you're almost in the way: using up resources that should go to reproduction-capable beings.I think I am understanding how only life up to reproduction (and perhaps successful child rearing after) matters in evolution.Trék

Jared Diamond in his book Guns, Germs, and Steel tells an ancedote about learning the botany on a pacific island I think. Don't have the book handy to refresh my memory. His informant would answer about what the people ate everyday, and only in tough times, and then with a word Jared couldn't understand. So the guy takes Jared to meet the old woman. She was toothless, her people had to chew food for her but she had been alive when a tsunami had struck the island and she remembered what the people could eat to survive such a disaster.Now these people didn't have written records. Old people were their knowledge base and they were important. They carried knowledge that could help the tribe survive disasters of rare occurances.It seems to me that this is a way human longevity could be selected for. Not perfectly but nevertheless it seems possible.The book is a fascinating overview of the developement of civilization and the way humans have spread across the planet.lfen

Wouldn't giving the knowledge over to someone else and letting the old woman die be more "efficient." It sounds like they did what they did out of concern and love for her.Trék

I'm hoping to do a lot of reading this summer and some of that would be reviewing books and Jared is a favorite author of mine. I honestly don't remember. I'll have to reread it to see. In fact that might have also been in a discussion about menopause as a way to avoid risking the life of older women in child bearing so that they would live longer to give extra support to their offspring thus giving greater survivability to their grandchildren.My memory conflates things with time and without Google or something like it I don't know what I'd do. I don't know if this argument is sound or not but I'm pretty sure that Diamond, or someone like him made it.At any rate human survival is resource intensive. A few offspring are given a lot of care for a long time so apparent efficiency may not always be what works.I know that's pretty fuzzy but it's something to consider.lfen

Please. In evolutionary terms all you need is old enough to breed. Beyond that no special limit one way or the other is necessary. It is of interest how old individuals were at death, but there is no need to show changing life spans one way or the other.What scientists do is look at the evidence to see how long individuals within species lived, and from that they make estimates about how long average individuals could live. What we see is a gradual increase in life span across millions of years, with some jumps and squiggles in the line - particularly any time a new technology is added that makes life easier.We do NOT, however, see ANY 'miraculously' old specimens of hominids, so where are all those old biblical type specimens from when everyone lived such long lives eh?It's not a matter of not believing, it's a matter of not having any evidence, and it's not a matter of not believing the bible story, it's a matter of not needing to believe ANY story of previously long lived humans -- because the evidence is that no early hominids lived that long, or even outlived modern humans.Enjoy.

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RebelAAmerican.Zen[Deist
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How can you tell how old a human was when it died from its fossil? Sure you can tell aprroximatley how long ago it died from carbon dating etc. What method is used to find how long it lived? But wouldnt the individuals that lived longer produce more offspring so they would pass on more genes to next generation?

Human bones undergo changes as the person ages. In the case of the skull its not one piece in the beginning as the person grows the bones of the skull fuse together.

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If "elitist" just means "not the dumbest motherfucker in the room", I'll be an elitist!
*not an actual doctor

As far as I know with the skull we are born with the skull unfused to assist with birth, but then the bones of skull fuse together pretty quickly after that (like a year or so). So i suppose that would be fine for aging todlers.Im referring more to adults when they are fully developed.

From the structure of the bones, the amount of cartilege, etc. Your bones don't stop growing when you are a toddler or you would never reach adult height. Then after that there are markers like osteoporosis that show age. Um, no. Carbon 14 dating is only good (1) for organic objects and (2) up to 50,000 years old. Fossils are usually older and have had the carbon atoms replaced by minerals. Other types of radiometric dating are used, generally on artifacts rather than the fossils directly. How old do you need to be to have 20 offspring? How many can you feed and protect? In every generation of every (wild) species more young are produced than survive to breed, it's part of the natural selection aspect.

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RebelAAmerican.Zen[Deist
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The skull was just an example of how bones change over time. Various other bones do various other things as the body ages.

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Just a monkey in a long line of kings.
If "elitist" just means "not the dumbest motherfucker in the room", I'll be an elitist!
*not an actual doctor