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0:00
This is Dr. James Fries, and
I'll be talking with you today
on the compression of
morbidity and the ways that we
have of postponing human aging.
0:12
Underlying our current
knowledge of human aging
are a number of central, rather
simple but often not familiar
facts.
The first number of slides
we'll go through these,
and I'll try and explain
them as we go through.
The current slide shows life
tables from the United States
at 20 year intervals
from 1900 to 1980.
Notice several things about
the way in which people die.
They begin at the left
side of the slide,
with zero deaths at age birth.
And then as they progress
through life to age 100 or so,
the curves develop depending
upon the year of birth
and are quite different
from each other.
In 1900, for example, there are
many early life deaths, or births
and deaths, and that causes
the curve to go down steeply,
and then to continue on
throughout the lifespan,
and then to emerge at the bottom
line at around age 100 or so.
The second curve is
1920, 20 years later.
In it, there are fewer
early life deaths,
and the line continues, as shown.
And again, it inserts
at the age of 100 or so.
The same thing happens
in 1940, in 1960, in 1980
until we look at the present curve,
which would fit in between the 1980
curve and the top of the slide.
There is very little room for
improvement any more below age 50.
If you take a look at age 50 and
just draw a line in your mind,
going up from the bottom
line to the second one,
you'll see that almost all of the
space that was previously available
is now not possible,
and there's only
a narrow little sliver of people
who are dying before the age of 50.
So the curves continue, and the most
noteworthy thing about this slide
is that these kinds of curves
all insert at the same place.
That indicates that the lifespan,
which is taking over for diseases,
which are what we're usually
counting, the lifespan
is fixed from decade
to decade, and that
has continued through the present.
When we are seeing
improved longevity,
as we are in most
developed countries,
that is due to a decrease
in early life deaths
and not to the force of mortality
in some broader way being abated.
This is a cause of a
lot of misstatement
of facts about human aging.
This would indicate here that
human survival has been fixed
at least for the past 115 years.
So the human lifespan
is biologically limited,
but our attention needs to be placed
on the age at first morbidity.
Now, I'll use morbidity a lot.
It's in general
synonymous with the term
"disability," or inability to
perform activities of daily living.
"Morbidity" is the term which we
frequently oppose to mortality,
and we use morbidity to indicate
everything that is part of illness
but doesn't result in death.