systems often injure us by treating various parts of ourselves
as though they too, were infectious invaders. This blindness
leads to conditions such as diabetes, multiple sclerosis, rheu-
matoid arthritis, and many others.
We are also subject to injuries that our bodies cannot repair.
Namely, accidents, dietary imbalances, chemical poisons, heat,
radiation, and sundry other influences can deform or chemi-
cally alter the molecules inside our cells so that they are unable
to function. Some of these errors get corrected by replacing
defective molecules. However, when the replacement rate is
too slow, errors accumulate. For example, when the proteins
of the eyes lenses lose their elasticity, we lose our ability to
focus and need bifocal spectacles.
Most likely, eventual senescence is inevitable in all biologi-
cal organisms. As we learn more about our genes and cellular
biochemistry, we will hopefully be able to correct, or at least
postpone many conditions that still plague our later years.
However, even if we found cures for each specific disease, we
would still have to deal with the general problem of wearing
out. The normal function of every cell involves thousands of
chemical processes, each of which sometimes makes random
mistakes. Our bodies use many kinds of correction techniques,
each triggered by a specific type of mistake. However, those
random errors happen in so many different ways that any low-
level scheme to correct them would be difficult indeed.
The problem is that our genetic systems were not designed
for very long-term maintenance. The relationship between
genes and cells is exceedingly indirect. To repair defects on
larger scales, a body would need some sort of catalogue that
specified where the various types of cells should be located
Essays on Infinite Lifespans
Marvin L. Minsky, Ph.D.