Will Robots Inherit the Earth?
HEALTH AND LONGEVITY
Such a future cannot be realized through biology. In recent
times we have learned a lot about health and how to main-
tain it. We have devised thousands of specific treatments for
particular diseases and disabilities. Scientists are seriously con-
sidering the possibility of extending the maximum human
life span, but we have not yet achieved this goal. According
to the estimates of Roy Walford, professor of pathology at
UCLA Medical School, the average human life span was about
22 years in ancient Rome; about 50 in the developed countries
in 1900, and today stands at about 75. Still, each of those curves
seems to terminate near 115 years . Centuries of improve-
ments in health care have had no effect on that maximum.
Why are our life spans so limited? The answer is simple:
Natural selection favors the genes of those with the most
descendants. Those numbers tend to grow exponentially with
the number of generations. This favors the genes of those
who reproduce at earlier ages. Evolution does not usually
favor genes that lengthen lives beyond that amount adults
need to care for their young. Indeed, it may even favor off-
spring who do not have to compete with living parents. Such
competition could promote the accumulation of genes that
cause death. We humans appear to be the longest-lived warm-
blooded animals. What selective pressure might have led to
our present longevity, almost twice that of our other primate
relatives? This is related to wisdom! Among all mammals, our
infants are the most poorly equipped to survive by themselves.
Perhaps we needed not only parents, but grandparents too, to
care for us and to pass on precious survival tips.
Even with such advice, there are many causes of mortality to
which we might succumb. Some deaths result from infections.
Our immune systems have evolved versatile ways to deal with
most diseases. Unhappily though, those very same immune