Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!umd5!brl-adm!cmcl2!yale!briscoe-duke
From: briscoe-duke@CS.YALE.EDU (Duke Briscoe)
Newsgroups: sci.bio,sci.med
Subject: Re: Mortality
Message-ID: <31342@yale-celray.yale.UUCP>
Date: 12 Jun 88 05:17:55 GMT
References: <36@feedme.UUCP> <1894@silver.bacs.indiana.edu>
Sender: root@yale.UUCP
Reply-To: briscoe-duke@CS.YALE.EDU (Duke Briscoe)
Organization: Yale University Computer Science Dept, New Haven CT  06520-2158
Lines: 23
Xref: utzoo sci.bio:1234 sci.med:5733

In article <1894@silver.bacs.indiana.edu> chiaravi@silver.UUCP (Lucius
Chiaraviglio) writes: 

>No, these mechanisms have not been determined, although it is definite
>that aging occurs at the cellular level.  Many people have thought
>that aging is the result of accumulated DNA damage, but this theory
>absolutely fails to explain how accumulation of DNA damage can lead to
>aging of individuals yet allow them to give rise to perfectly young
>offspring.  ...

I don't think this is a valid point against the DNA damage
accumulation theory.  Some damage does occur to eggs and sperm as
individuals age.  People do become sterile with age (for various
reasons, some of which may be related to DNA damage to germ cells).
Germ cells with too much damage may result in miscarriages.  Less
damage may result in viable mutations, which may be harmful, neutral,
or beneficial.  Also, note that testicles are kept outside of the main
body cavity where the temperature is slightly lower, which I believe
is an adaptation to lower the rate of chemical mutagenic reactions.
Perhaps this is related to the extended fertility of men versus women
(once again, there can be other factors involved in this phenomenon).

Has anyone seen this theory for the evolution of external testicles
before?