Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
8 online now:
Newest Member: popoi
Post Volume: Total: 915,817 Year: 3,074/9,624 Month: 919/1,588 Week: 102/223 Day: 13/17 Hour: 1/1


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Human Life Span & Evolution
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 34 of 71 (317342)
06-03-2006 7:44 PM
Reply to: Message 1 by Jon
05-29-2006 5:02 AM


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.

Join the effort to unravel {AIDSHIV} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 1 by Jon, posted 05-29-2006 5:02 AM Jon has not replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 40 of 71 (317551)
06-04-2006 9:39 AM
Reply to: Message 35 by watzimagiga
06-03-2006 9:45 PM


Re: huh?
Please.
... my point was that in evolutionay terms its doesnt make sense to believe that people could have at one stage lived 900 years.
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.

Join the effort to unravel {AIDSHIV} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 35 by watzimagiga, posted 06-03-2006 9:45 PM watzimagiga has replied

Replies to this message:
 Message 41 by watzimagiga, posted 06-05-2006 2:19 AM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 44 of 71 (317829)
06-05-2006 6:49 AM
Reply to: Message 41 by watzimagiga
06-05-2006 2:19 AM


Re: huh?
How can you tell how old a human was when it died from its fossil?
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.
Sure you can tell aprroximatley how long ago it died from carbon dating etc.
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.
But wouldnt the individuals that lived longer produce more offspring so they would pass on more genes to next generation?
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.

Join the effort to unravel {AIDSHIV} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 41 by watzimagiga, posted 06-05-2006 2:19 AM watzimagiga has replied

Replies to this message:
 Message 48 by watzimagiga, posted 06-05-2006 5:52 PM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 51 of 71 (318122)
06-05-2006 8:13 PM
Reply to: Message 48 by watzimagiga
06-05-2006 5:52 PM


Age at Death estimates
Okay, so from birth until full development, say 0-20, we can tell pretty accurately how old the person was at death.
There are changes that are still occurring after 20.
Here is a good (easy read) site for an overview of the methods and problems
http://www.spoilheap.co.uk/hsrspec.htm
Adult age at death is not so easy to estimate, and becomes increasingly difficult past the age of c.30 years. Once the teeth are fully erupted, age can be estimated from standard tooth wear charts, although the rate of wear is dependent on the type of food as well as the age. Most charts allow for an estimate of age within ten year periods. Another method is to use the changes which occur at the pubic symphsis (the joint at the front of the pelvis). This is generally ridged in the young adult, and becomes progressively smoother with age (other changes are also taken into consideration). However, this part of the skeleton is rarely preserved in ancient skeletons, and the method is very difficult to use accurately when it is. The stage of fusion of the cranial sutures was used in the past, but this method is no longer thought to be accurate. The general appearance of the bones may suggest a basic age category, particularly if arthritic changes or other signs of aging are present. Evidence from recent work on the documented skeletons from Spitalfields in London, suggests that many of the skeletal ageing techniques commonly used by human bone specialists produce inaccurate results. It seems that we may be underestimating the age at death of adults by some decades, the greatest problem concerning the older members of a skeletal population. Often the best the specialist can do is to suggest that an individual was young, middle-aged or old, since to provide more detailed estimates would be misleading.
I think they are overstating the degree of uncertainty here, as you can build up a database and have relative ages of different specimens, then you can make assumptions about how old they were in relative development of certain characteristics. The more samples they have the better the overall accuracy.
Should be good enough to get to +/-10 years eh?
Once all the biological evidence has been collected, it has to be interpreted taking into account the limitations imposed on the data by the methods used. The most useful information for the archaeologist is the demographical profile of the site. This will provide information on the minimum number of individuals, the infant mortality, sex ratios (which unfortunately cannot include the children), and life expectancy.
Here they seem to be pretty confident of having good age estimates, so the above statements can be taken as a bit "CYA"
Assuming that there is a 1 year gap between each child. Then by the time you have your 20th child, the earlier children would be becoming pretty self sufficient.
Ah, the nearsightedness of growing up in a well nourished, healthy society, eh? Look back 100 - 200 years and see what infant mortality was like. Families that had 6 or 7 kids usually had 2 to 3 survive to mate, now we have families with 2 or 3 kids 99% of whom survive to mate -- we live longer healthier lives but end up with about the same net productivity numbers eh?
You make it seem almost like factory output production, put more raw materials in and get more product.
However this is only 1/4 of the equation at best:
Sexual Selection -- a young handsome Lothario (like you?) is more likely to succeed at mating than an old cane tapper (like me?) because sexual selection is NOT based on {older is better}, and
Ecological Load --the environment only supports so many individuals. If you try to have more than that number of individuals, then they all suffer malnutrition to some degree and the more vulnerable die.
The genes for long life are not necessarily the genes that work for survival until mating age is attained, especially if they also code for longer growth time before becoming fertile
Are you trying to say that no matter how old a person lives, there is a cap on how many children they can have.
There is a limit to how big the group can be. Once that size is reached the first ones to die will be the infants.
Think of it this way: if productivity were the only factor, then multiple births would be selected for -- more families would have twins.
Triplets would still be a problem unless the average size of the human breast also increased to compensate for the insufficient number of nozzles, but there are also relatively common mutations of having extra teats on one breast (see POLYTHELIA or POLYMASTIA)
Supernumerary nipple - Wikipedia
A supernumerary nipple (also known as a third nipple, accessory nipple, nubbin, polythelia or polymastia) is an additional nipple occurring in mammals including humans. Often mistaken for moles, supernumerary nipples are diagnosed at a rate of 2% in females, less in males. The nipples appear along the two vertical "milk lines", which start in the armpit on each side, run down through the typical nipples and end at the groin. They are classified into eight levels of completeness from a simple patch of hair to a milk-bearing breast in miniature. Polythelia refers to the presence of an additional nipple alone while polymastia denotes the much rarer presence of additional mammary glands.
So if productivity were the only issue then multiple breasts and larger numbers of multiple births would also be selected.
That this is not so, also points to groups only being able to support a certain number of offspring on any one year.
Infant survival can be improved with more attention, better nutrition, etc, but this means spending more time {with\on} raising young so raw productivity falls for an increase in net productivity -- we may be selecting FOR older age by selecting for taking more time for each infant. This trend is seen in many species, however humans seem to have taken altricial to new heights.
Enjoy.

Join the effort to unravel {AIDSHIV} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 48 by watzimagiga, posted 06-05-2006 5:52 PM watzimagiga has replied

Replies to this message:
 Message 52 by watzimagiga, posted 06-05-2006 9:35 PM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 54 of 71 (318217)
06-06-2006 7:31 AM
Reply to: Message 52 by watzimagiga
06-05-2006 9:35 PM


Re: Age at Death estimates
What does wear of teeth mean? Do they slowly get filed down and get smaller every time we eat?
Yes, but more like sandpaper or emery cloth. Some foods more than others, and some diets more than others. Indians in the southwest the ground corn on stone also got some of the stone in the corn flour, and this caused increased wear in their teeth.
Because for a person to live for 800 years, the rate at which their body deteriorates would have to be less than a modern (todays) human.
It would have to be supernaturally enhanced eh? So that current rules don't apply? Without any evidence of any other way the rules don't apply?
See that is the problem. You can take any mythological story and start playing games with the evidence and the science to see how it could actually have occurred, but at the end of the day there is no real reason to assume that such is the case - other than wanting to believe that the myth in question is true.
The other problems you have are that the rest of the evidence doesn't fit either, the stature of the fossils gets smaller and the braincases get smaller, so you don't have tall noble intelligent people in the distant past no matter how long they lived. The fossils go back from us to Lucy, between 3'-6" and 4'-0" tall (see PubMed Article Abstract).
Enjoy.

Join the effort to unravel {AIDSHIV} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 52 by watzimagiga, posted 06-05-2006 9:35 PM watzimagiga has replied

Replies to this message:
 Message 55 by watzimagiga, posted 06-06-2006 8:32 AM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 56 of 71 (318443)
06-06-2006 9:01 PM
Reply to: Message 55 by watzimagiga
06-06-2006 8:32 AM


Re: Age at Death estimates
You have mentioned lucy a couple of times now. Lucy was not found intact in one place. I read that the bones, including the knee (which showed, she was probably bipedal) were not just found in different areas, but actually at different depths, showing different age of bones. Sorry if this is off topic, just when people talk about lucy I feel I need to bring this up.
You realize that this is claiming that Lucy is a fraud, and that the scientists are charletans. That's a pretty serious accusation to just drop. I'll just say that your "source" is misrepresenting the truth to you. But you are right this should be a separate topic and NOT discussed here.
This is also a science thread, and statements like that need to be substantiated or withdrawn. I've set up a new thread for this:
http://EvC Forum: Lucy - fact or fraud? -->EvC Forum: Lucy - fact or fraud?
{link edited to promoted version}
Yup, well I have already said that they couldnt have lived 900 years without God being involved somehow.
the rest of the evidence doesn't fit either, the stature of the fossils gets smaller and the braincases get smaller, so you don't have tall noble intelligent people in the distant past no matter how long they lived
I dont see how this is relevant to people living long lives.
Because it is part of the same {concept\myth\story} and without it there is no purpose to consider long lives that don't match the fossil record anyway.
I think I have shown that even if we had one on front of us we wouldnt be able to tell.
I find it hard to believe that we could be off by a factor of 2 with our current knowledge of aging patterns (ie a "70" year old could really be 140 years old), and what you need is a factor of 10 to 12. All you have shown is that we may not know that our "70" year old was really 50 or 90.
Enjoy.
Edited by RAZD, : changed link to promoted version of new topic

Join the effort to unravel {AIDSHIV} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 55 by watzimagiga, posted 06-06-2006 8:32 AM watzimagiga has replied

Replies to this message:
 Message 58 by watzimagiga, posted 06-06-2006 11:39 PM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 59 of 71 (318631)
06-07-2006 8:08 AM
Reply to: Message 58 by watzimagiga
06-06-2006 11:39 PM


Re: Age at Death estimates
I'll answer you more fully after you respond to the new thread
http://EvC Forum: Lucy - fact or fraud? -->EvC Forum: Lucy - fact or fraud?
This is a serious allegation of professional misconduct you have made and this is a science thread. Substantiate your claim, provide your source, or withdraw the claim.
Then we can chat about hypotheticals.
Enjoy.

Join the effort to unravel {AIDSHIV} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 58 by watzimagiga, posted 06-06-2006 11:39 PM watzimagiga has not replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 60 of 71 (319268)
06-08-2006 8:11 PM
Reply to: Message 58 by watzimagiga
06-06-2006 11:39 PM


Re: Age at Death estimates
Where does the bible mention anything about the height of the people it mentions? It also does not say that they had larger brain cases than us. So really this isnt really contradicting any of the evidence, because the bible talks nothing about either of these issues.
Well that is the impression I get from creationist talk about humans today being lesser beings than they were before the flood (shorter lived, more brutish, etc etc).
If you are saying that adam and eve could be similar in stature, physique and mental capacity to lucy, I can go with that, because that is the evidence of human ancestry.
But I still need some kind of other evidence that suddenly there was less wear on teeth, say, at some point in the past that allows for not just a doubling of age based on that marker but a 10 to 30 fold increase in age:
900 yr age / 25 yr old lucy = 36 fold increase in age.
I thought we were in agreement on the idea that, if these people who lived long lives deteriorated (wear of teeth etc) at a different rate, we would not be able to age them accuratley (ie we could not tell they lived 900 years).
There has to be some evidence that permits this concept: a remarkably different diet? Not based on the archaeological evidence of garbage left by early hominids, particularly after the 'invention' of fire (so charred bones can be compared).
There has to be some evidence that plants or animals would cause substantially less wear on teeth than they do now - 1/10th to 1/36th the wear. Yet there is no evidence that plants and animals have ever been composed of substantially different materials or that teeth were ever substantially harder - they are composed of same materials with same distributions of materials based on the fossil evidence. Before cooking was used to break down food fibers the wear would have to be greater on the teeth than on modern humans ('modern' here meaning Homo sapiens, covering the last 200,000 years).
We know that teeth have not changed substantially because we have evidence of juvinile teeth and jaws as well as the teeth and jaws of adults, and the patterns of growth and the distribution of materials (enamel particularly) on the teeth are similar to what we see in 'modern' humans.
This is important because living that long would not be possible unless they aged at a different rate.
Or some miracle was involved that negates all scientific evidence, but yes, that would be why these ages would be considered scientifically unreasonable.
Enjoy.

This message is a reply to:
 Message 58 by watzimagiga, posted 06-06-2006 11:39 PM watzimagiga has not replied

Replies to this message:
 Message 64 by Jon, posted 06-12-2006 8:21 AM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 61 of 71 (319273)
06-08-2006 8:30 PM
Reply to: Message 57 by EZscience
06-06-2006 10:04 PM


selection currently acting to increase human lifespan?
it is perhaps more instructive to consider why selection should be currently acting to increase human lifespan
Is it? or is the lifespan increases purely 'environmental' in that it is our increased knowledge of medicine and health that allows people to reach their potential more often?
Average lifespan in developing countries is not all that much different, so when adverse conditions are present it reduces the likelyhood of surviving to old age.
There could be selection for better protection of {children\youth} in populations due to having more able-bodied adults around that would select for the children of those who live {longer+healthy} lives, but this may also select for populations that have fewer children so that they are easier to protect with the resources you have available.
And it may select for populations where children take longer to reach maturity. Some estimates put humans at reaching self-sufficiency at age 10 or so -- compare this to other ape ages or even other mammals -- and that isn't even reaching sexual maturity yet (13?).
Selecting for fewer kids and slower growing kids could select for increased age in adults to compensate for the loss in offspring productivity, as those who were shorter lived would not live long enough to protect the last batches adequately, putting more strain on other members of the group (or increased abandonement).
Isn't there some general relationship between the time it takes for young to reach maturity in a species and the length of life of the species (at least for those where the young are cared for by at least one adult)? Consider elephants for instance.
In animals where there is no 'penalty' for taking care of the kids (say alligators and turtles?) increased longevity of the adult would be selected for by reproductive advantage, yes?

Join the effort to unravel {AIDSHIV} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 57 by EZscience, posted 06-06-2006 10:04 PM EZscience has replied

Replies to this message:
 Message 62 by EZscience, posted 06-09-2006 11:56 AM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 63 of 71 (319682)
06-09-2006 7:57 PM
Reply to: Message 62 by EZscience
06-09-2006 11:56 AM


Re: Increasing human lifespan more a consequence of selection targeting other traits
I don’t think kids are growing slower or maturing later ...
I was thinking more in terms of on the way to modern human, say up to 200,000 years ago when Homo sap got his\her first legs.
Looks like sexual maturity is reached about the same time for chimps, bonobos and humans:
National Geographic Article on Gombe (click)
San Diego Zoo Article (click)
Animal Info - Bonobo (click)
12 to 13 years.
When we compare old ages of chimps, bonobos and humans we see 40 to 50 years for chimps and bonobos, comparable to hominid ancestors, but twice that for modern humans?
This is ”r’ versus ”K’ selection ... There have been many criticisms of this conceptualization
I was thinking more in terms of subsets than the whole range - comparing all species that cared for young for instance - to see if more can be teased from the data.
... if parents contribute to their offspring’s reproductive success late into life, there would be advantages for increasing parental longevity beyond reproductive age. Think about how many grandparents are important providers of child care for their kids.
I ran across this article:
YES Magazine Article - Respecting Elders, Becoming Elders (click)
But haven't read it enough to evaluate how much valid how much opinion. But read the "First Grandmother" section eh?

Join the effort to unravel {AIDSHIV} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 62 by EZscience, posted 06-09-2006 11:56 AM EZscience has not replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 66 of 71 (320938)
06-12-2006 8:06 PM
Reply to: Message 64 by Jon
06-12-2006 8:21 AM


Re: Age at Death estimates
Dating methods wouldn't bracket the age of a fossil with anything like a valid number, if this is what you are meaning -- we can't date when an organism was born, and only 14C dating method relies on the decay of 14C to measure how long ago the organic sample stopped taking in atmospheric carbon (to date when the sample died). Dating the layer under the fossil could easily provide a false "life" of thousands of years - heck we can walk on rocks that are over 3 billion years old eh?
The methods we have to judging age at death are fairly limited and are based on our medical knowledge of human and animal changes with age.
In order to arrive at a theoretical age of 800 (normal?) years for a fossil there would have to be some rather extraordinary aspects -- all teeth there, but worn down to a nub, severe arthritis, the loss of all cartilege in joints and the subsequent wear on the bones, etcetera.
The fossil would be more likely regarded as deformed and diseased than old.
This is based on applying the tests for age on the fossil to actually test out to 800 years old, rather than taking 800 years and seeing how they would not test to the right ages.
Does that answer your question?

Join the effort to unravel {AIDSHIV} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 64 by Jon, posted 06-12-2006 8:21 AM Jon has replied

Replies to this message:
 Message 67 by Jon, posted 06-15-2006 2:57 PM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 69 of 71 (333818)
07-20-2006 8:14 PM
Reply to: Message 67 by Jon
06-15-2006 2:57 PM


Re: Age at Death estimates
So if the individual had been an extrememely healthy 800-year old man, we wouldn't see these signs. Would we then date the sample as being very young?
"Extremely healthy" would allow a person to live to 90 instead of 40 or 50 years, but it would not decrease the wear and tear on teeth and joints, that would still be progressive.
So then the answer is "yes?" If we did date an individual to be 800 years old, we would look for other explanations instead of accepting the 800-year old number.
No, this is taking the tests we have for age and then extrapolating what the results would be for an 800 year old specimen, independent of health. We would then look at that specimen and see what could be concluded -- and as I said we would see "some rather extraordinary aspects -- all teeth there, but worn down to a nub, severe arthritis, the loss of all cartilage in joints and the subsequent wear on the bones, etcetera."
What we would likely conclude about age at death is that it would be indeterminate due to the {excessive damaged and crippled} ("EDC") condition of the specimen.
The age dating methods use cross-references between age and wear that we have accumulated (including references to mummies and other ancient bodies where the age is known). We also have correlation checks with juvenile fossils that show wear at these rates, while the bones are still not fully formed compared to adults in the same populations. These latter fossils rule out cultures with excessive wear pattern due to culture specific behavior (say eating sand) because the increased rate shows up in the young population.
This means that to posit an over 10-fold increase in age from what is know that you need to have some mechanism to reduce wear and tear well below normal levels.
You need to assume a supernatural explanation for how they age without showing it in order to show evidence for a supernaturally aged fossil. This is begging the question.
Now I don't really see the use for speculations like this, because they are all "what if" stories, and the "what ifs" can go on for whatever.
If there were a population that had a high incidence of what appeared to be "EDC" fossils -- all having the same characteristics of excessively worn teeth and bones and the like, then there might be cause for {investigating\theorizing\speculating} why and how this came to be.
There isn't.
If that population were also mixed with others of intermediate ages that showed a clear progression from normal young age to the "EDC" fossils with normal patterns for the very young and sufficient intermediates between them to fill the demographics necessary, showing intermediate stages between normal adult wear and the "EDC" fossils, then you might have evidence to consider an old age.
There isn't.
If there were a number of isolated fossils that showed "EDC" characteristics you might have cause to speculate on an old age.
There isn't.
The worst we have are fossils that cannot be dated because there is not enough there to provide the data. This of course proves that an old age is possible ... (if that is what you NEED to prove to yourself at all costs so you can be comfortable with some belief or other anyway).
Also see {Bone Maturation}
Bone age - Wikipedia
Page not found - Image Sciences Institute
for fairly accessible articles on some of the changes in the skeleton structure with age.
As long as all of the markers that we have for age development occur in normal patterns you cannot then assume some fantastic age for those fossils.
Now consider Histomorphometric age assessment of the Boxgrove 1 tibial diaphysis:
The bone fragment from Boxgrove 1 presents an unusual situation for age assessment, because the tibia is the only skeletal element recovered for this individual. As a result, the individual’s age-at-death cannot be assessed by macroscopic methods, and it must be evaluated through histological means.
The histological methods developed for estimating age-at-death are bone specific. Several age estimation methods for use on the tibia have been proposed (Kerley & Ubelaker, 1978; Thompson, 1979; Thompson & Galvin, 1983; Uytterschaut, 1985) with Kerley & Ubelaker’s method (1978) being most widely used by biological anthropologists.
Because subsequent application of the original tibial regression formula (Thompson, 1979) found it to overestimate age, a new formula was proposed by Thompson & Galvin (1983). The new formula utilized only the number of whole secondary osteons per mm2 (n.On), which proved to be the best predictor of age in individuals less than 55 years.
Microscopic examination of the fragment of bone from the tibia of Boxgrove reveals substantial histomorphological preservation and virtually all fields are readable. Distinct histomorphological features, such as osteons and osteon fragments, are sufficiently identifiable and quantifiable to permit an histomorphometric age assessment of these remains (Figure 2). Application of the Thompson & Galvin (1983) predicting formula yields an estimate of the age-atdeath of 39·5 years with a range of 31·0-48·0 years for the Boxgrove tibia. The earlier Thompson (1979) formula provides a much higher age (62·6 years+/-8·9 years) (Table 2).
For comparison, histological ages from the Shanidar 2 early Late Pleistocene Neandertal tibia are also provided (Table 2). Macroscopic age indicators for Shanidar 2, in particular the degree of attrition of its complete dentition compared to those of otherwise aged late archaic human specimens from Shanidar and other sites, indicate a young adult age, most likely during the third decade of life (Trinkaus, 1983). Our histomorphometric age estimate using the Thompson & Galvin (1983) formula yields a slightly older age but the probable range encompasses the macroscopic age estimate for this individual. This correspondence provides confidence that the age estimate for Boxgrove 1 in the fourth or early fifth decade of life is appropriate. If anything, the older histomorphometric age, as opposed to dental attrition age-at-death, for Shanidar 2, may suggest that the histomorphometric age for Boxgrove 1 is slightly overestimating its actual age-at-death.
Regardless of the resolution of these issues regarding the calibration of age indicators among pre-Late Pleistocene archaic Homo populations, it is apparent that the known Middle Pleistocene hominid fossil record has an underrepresentation of older individuals, with the current record dominated by young adult and immature remains. Although a variety of taphonomic, behavioral and paleontological processes may contribute to this age bias in the sample, a combination of demographic stress and local population demographic instability may have been a major contributor to the observed pattern (see discussion in Trinkaus, 1995).
At the same time, the present study has shown that histomorphometric methods provide a means to estimate the age-at-death of fragmentary paleontological material such as the Boxgrove 1 tibia. The application of these methods to large samples of Middle Pleistocene archaic Homo where other aging methods can be employed (e.g., the Atapuerca-SH sample) is therefore highly desirable and would help both to refine the level of consistency of these histomorphometric methods with other approaches and expand our paleobiological assessments of these archaic hominids.
Notice four things:
(1) They can measure age up to 55 years by this method -- not just juvenile development.
(2) They also correlate this with samples with teeth wear to show that they have the same age (they didn't have to, and in fact there is a slight difference).
(3) There are other methods for estimating age-at-death.
(4) This paper is discussing the accuracy of the estimates, the correlations that validate the age estimates and how to make those estimates better.
See Dynamic bone remodeling in later Pleistocene fossil hominids. for another early hominid age-at-death study (abstract only).
See also {Dinosaur Fossil Bone Leads to Gender, Age Determinations } and {X-ray microanalysis of fossil dinosaur bone: age differences in the calcium and phosphorus content of Gallimimus bullatus bones. } for some other information related to estimating age-at-death.
Enjoy.

Join the effort to unravel {AIDSHIV} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmericanOZen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 67 by Jon, posted 06-15-2006 2:57 PM Jon has not replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 71 of 71 (342848)
08-23-2006 7:33 PM
Reply to: Message 70 by Aegist
08-22-2006 11:57 PM


cool
Thanks Shane,
I notice that the second link can be shortened to
Telomere.org
I also noticed recent reference to the "hobbit" fossil as a 73 year old woman that lived 18,000 years ago
http://dsc.discovery.com/news/2006/08/21/hobbit_hum.html
And have seen other references to old people in ancient sites and that indicate that such age is not outside the possibilities for those people.
Thanks.

Join the effort to unravel {AIDS/HIV} {Protenes} and {Cancer} with Team EvC! (click)

we are limited in our ability to understand
by our ability to understand
RebelAAmericanOZen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 70 by Aegist, posted 08-22-2006 11:57 PM Aegist has not replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024