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Author Topic:   Amino Acid Dating
faith24
Junior Member (Idle past 1957 days)
Posts: 27
Joined: 09-10-2010


Message 1 of 34 (580700)
09-10-2010 6:43 PM


I'm not too familiar with this method of dating, however, it has to do with the constant change called racemization. Racemization change over time due to temperature. Can somebody please explain how this method is use to determine the age of fossils? Here is an article that shows a racemization chart.

http://grisda.org/origins/12008.htm

So it seems that's these changes makes this method useless. How would you explain to someone that say "since the change of this constant is exactly what allows the elapsed time to be determined." Is this true? And how do they know?

Edited by faith24, : No reason given.


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faith24
Junior Member (Idle past 1957 days)
Posts: 27
Joined: 09-10-2010


Message 7 of 34 (580712)
09-10-2010 8:13 PM
Reply to: Message 6 by AZPaul3
09-10-2010 7:40 PM


Re: Don't do it!
I see. Thanks for clarifying that to me. Can you please basically explain the contamination process that it go through? What does it mean when people say "how do you know the fossils aren't contaminated"? Thank you.

This message is a reply to:
 Message 6 by AZPaul3, posted 09-10-2010 7:40 PM AZPaul3 has acknowledged this reply

  
faith24
Junior Member (Idle past 1957 days)
Posts: 27
Joined: 09-10-2010


Message 9 of 34 (580716)
09-10-2010 8:29 PM
Reply to: Message 5 by Coyote
09-10-2010 7:30 PM


I heard that there are other method which overlap this one - Amino Acid Racemization? Do you know the relationship between this one and why it must depend on other one, such as C-14?

Edited by faith24, : No reason given.


This message is a reply to:
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Replies to this message:
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faith24
Junior Member (Idle past 1957 days)
Posts: 27
Joined: 09-10-2010


Message 11 of 34 (580732)
09-10-2010 9:16 PM


Amino Acid dating was use by Jeff Bada to date the California Skeleton led to in error back then. Does anybody know why they were in error? Here is a short article discussing about it:

http://links.jstor.org/pss/280327

Edited by faith24, : No reason given.

Edited by faith24, : No reason given.


  
faith24
Junior Member (Idle past 1957 days)
Posts: 27
Joined: 09-10-2010


Message 12 of 34 (580735)
09-10-2010 9:25 PM
Reply to: Message 10 by Dr Adequate
09-10-2010 9:13 PM


quote:
If you want to test the reliability of a dating method, naturally you want to test it on objects of a known date. In the case of racemization, that would involve testing it on objects which have been dated historically (for example a book which is known to have been published in a particular year); or against objects which have been dated by dendrochronology; or against objects which have been carbon-dated. For the tests to be meaningful, the dating methods you're testing it against must be reliable.

So that mean racemization is dependent on other methods that can be reliable. How does that solve the overlapping that are in the AAR testing itself within the error bound?


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faith24
Junior Member (Idle past 1957 days)
Posts: 27
Joined: 09-10-2010


Message 14 of 34 (580754)
09-10-2010 10:18 PM
Reply to: Message 13 by Dr Adequate
09-10-2010 10:06 PM


quote:
How does that solve the overlapping that are in the AAR testing itself within the error bound?

It's ok forget it. =)


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faith24
Junior Member (Idle past 1957 days)
Posts: 27
Joined: 09-10-2010


Message 15 of 34 (580756)
09-10-2010 10:33 PM


Can somebody please basically tell me why Jeff Bada made an error in his methodology for dating California skeletons using Accelerator Mass Spectrometry (AMS) back in 1983? He was the guy that came with a new way of dating fossils - Amino Acid dating. Here is the article:

http://www.nature.com/...journal/v312/n5993/pdf/312442a0.pdf

Edited by faith24, : No reason given.


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faith24
Junior Member (Idle past 1957 days)
Posts: 27
Joined: 09-10-2010


Message 20 of 34 (580764)
09-11-2010 1:19 AM
Reply to: Message 19 by Coyote
09-10-2010 11:59 PM


Re: AAR errors
quote:
Bada did not use AMS (a form of radiocarbon dating). He used amino acid racemization. He dated eleven early California skeletons and came up with very old dates.

Others disputed those dates. Finally, Taylor dated those eleven skeletons using AMS dating and established that they were not nearly as old as Bada claimed. These younger ages were more in keeping with the archaeological data.

I am not sure of the exact reasons for the errors in these AAR dates, but most archaeologists don't bother with AAR now, using the radiocarbon method instead, as that has been shown to be reliable.


Right, i see now. Bada's view were incorrect and the errors are rather large up to 50% which is fairly narrow. But in general, i heard that there are better dating methods out there that can confirm this one? Do you happen to know? Thanks!


This message is a reply to:
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Replies to this message:
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faith24
Junior Member (Idle past 1957 days)
Posts: 27
Joined: 09-10-2010


Message 23 of 34 (580769)
09-11-2010 1:44 AM
Reply to: Message 22 by Coyote
09-11-2010 1:36 AM


Re: AAR errors
quote:
Confirm which one? AAR is prone to errors and none of the archaeologists I know use it. It has not been confirmed by radiocarbon dating, as the Taylor article I cited above shows. (I have a copy of the article at the office, and have met the author on a number of occasions.)

Well i heard that this method does support other dating methodologies that are sound. If you have many different methods of measuring that work on independent principles, and they all come out to values within error bounds of each other, then this indicator that they are sound methods. Is that true? hrmm...


This message is a reply to:
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Replies to this message:
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faith24
Junior Member (Idle past 1957 days)
Posts: 27
Joined: 09-10-2010


Message 29 of 34 (580811)
09-11-2010 1:00 PM
Reply to: Message 24 by Coyote
09-11-2010 2:09 AM


Re: AAR errors
quote:
If a variety of different methods all point to the same answers then that would tend to confirm those answers.

With dating, we have a lot of methods that can be used, and if they all point to the same approximate date that both confirms that date and supports the accuracy of each of the dating methods.


Sorry, i am new to this that's why i keep asking you questions. Can you tell me two things:

1. What are the other methods that can be used to support each other?
2. How do they support to each other?
3. What are the assumptions/interpretation being used?

Thanks for the article, i enjoy reading it.


This message is a reply to:
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Replies to this message:
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faith24
Junior Member (Idle past 1957 days)
Posts: 27
Joined: 09-10-2010


Message 31 of 34 (580825)
09-11-2010 2:40 PM
Reply to: Message 30 by Coyote
09-11-2010 1:26 PM


Re: On dating
Thanks for the help Coyote those are excellent sources, i am reading right now. Just curious, do you accept long or young ages? Those sites you posted looks like their young ages.

This message is a reply to:
 Message 30 by Coyote, posted 09-11-2010 1:26 PM Coyote has responded

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