Extending the lifespan: problems and questions

[William Calvin]

The issue probably revolves around whether the brain could continue to
learn new information (at least, in a way that could still be retrieved
efficiently) if the lifespan doubled.  There is one line of evidence that
information is stored by something of a carving process, where if you keep
adding things, you are in some danger of running out of synapses to carve.
   Between 8 months of age and puberty, we lose 30-50% of our synapses in
cerebral cortex.  The trend is downhill in adulthood, but there isn't too
much good data yet (and we don't really know what it means, either).  I
discuss this a bit about p.190 of my book THE ASCENT OF MIND (Bantam
1990), and there is a graph of the synapse decline with age in man and monkey.

    William H. Calvin   WCalvin at U.Washington.edu
    University of Washington  NJ-15
    Seattle, Washington 98195 FAX:1-206-720-1989