[ExI] Cryonics is getting more respect from the courts

Stathis Papaioannou stathisp at gmail.com
Sun May 23 13:24:52 UTC 2010


On 23 May 2010 03:44, Stefano Vaj <stefano.vaj at gmail.com> wrote:
> On 20 May 2010 19:22, Damien Broderick <thespike at satx.rr.com> wrote:
>> Not at all sure that "essentialist" is the right word to describe someone
>> like me. "Continuist" or something, maybe, if there is such a philosophical
>> category.
>
> Never paid attention to the fact that you were one... ;-)
>
> But let me understand your stance better: do you demand that any
> arbitrarily low degree of material continuity is never broken at any
> instant (as in Moravec-style uploading or in the seven-year cycle of
> biological replacement of human molecules), but accept for the rest a
> definition of identity which might allow for the entire replacement of
> the "substratum" provided that such continuity is conserved, or...? In
> fact, in my "relativistic" view on the issue, this might well have at
> least some symbolic meaning...

The replacement is probably faster than 7 years, especially for a
metabolically active tissue such as brain. The following papers
suggest that neuronal proteins in mice turn over
with a half-life of between 15 hours and 10 days (other neuronal
components such as water and ions would of course turn over much more
quickly):

http://www.ncbi.nlm.nih.gov/sites/entrez?db=PubMed&cmd=Retrieve&list_uids=1259983

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1164796

The following report relating to studies on rat embryonic neurons
suggests a very rapid turnover at synaptic junctions, such that within
10 hours the entire synaptic structure has been completely replaced:

http://www.ninds.nih.gov/news_and_events/news_articles/news_article_synapses.htm


-- 
Stathis Papaioannou



More information about the extropy-chat mailing list