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From: eddy@boulder.UUCP
Newsgroups: sci.med,sci.bio
Subject: Re: Dating age of humans
Message-ID: <2195@sigi.Colorado.EDU>
Date: Sat, 12-Sep-87 21:07:31 EDT
Article-I.D.: sigi.2195
Posted: Sat Sep 12 21:07:31 1987
Date-Received: Sun, 13-Sep-87 10:14:15 EDT
References: <26333@sun.uucp> <1960@kitty.UUCP> <3836@cit-vax.Caltech.Edu> <694@sugar.UUCP> <2001@kitty.UUCP>
Sender: news@sigi.Colorado.EDU
Reply-To: eddy@boulder.Colorado.EDU (Sean Eddy)
Organization: University of Colorado, Boulder
Lines: 29
Keywords: Ageing Human Carbon
Xref: utgpu sci.med:2792 sci.bio:592

In article <2001@kitty.UUCP> larry@kitty.UUCP (Larry Lippman) writes:
>In article <694@sugar.UUCP>, peter@sugar.UUCP (Peter da Silva) writes:
>> Couln't you do radioisotope testing on tooth enamel, and at least
>> get the age since dentition?
>
>	There are two problems that I see with this idea:
>
>1.	Carbon-14 has a half-life of approximately 5,730 years.  Since the
>2.	While I don't claim to have an in-depth understanding of tooth
>	physiology, it would seem to me that there would be some migration
>	of comtemporary C14 into the enamel, thereby nullifying any attempt
>	to perform age calculations even IF the C14 decay could be measured.

I am poorly informed on this, but a textbook of mine (it's a
freshman text for a class I'm TA for) mentions briefly that you
can date the age of a human by tooth enamel. No new protein is
laid down in the tooth, so there is no amino acid turnover during
one's lifetime. Amino acids are normally left-handed, but will
slowly racemize and head for equilibration between right- and
left- handed forms, if left alone like in tooth enamel (or
in the crystallins on the lens of the eye). The book
claims that a measure of right- vs. left-handedness in the amino
acids of the tooth can provide a fair measure of one's age. 

No radioisotopes necessary. Voila!

- Sean Eddy
- MCD Biology; U. of Colorado at Boulder; Boulder CO 80309
- eddy@boulder.colorado.EDU		!{hao,nbires}!boulder!eddy