The term senescence represents the processes which result
in an increase of mortality with age.
Senescence is ubiquitous in biological systems - but it is not
Some species exhibit negligible senescence - they age so slowly that
the cause of death typically has little to do with an organism's age.
This raises the question of whether the future dominant organisms on
the planet will continue to be among those that exhibit senescence -
or whether they will see aging as an undesirable pathology - and ensure
that they do not suffer from it.
Theories of senescence
Any reassonable predictions of what will happen to the aging
process in the future need to be made in the context of an
understanding of why aging happens in the first place.
The causes of senescence are thought to be many and varied.
They are discussed in some detail in my
Universal Senescence essay.
A fix for aging?
Some anti-aging enthusiasts seem to envisage fixing the
aging process via technological means.
It seems high on the agends of some transhumanists - e.g. see
[The Fable of the Dragon-Tyrant]
by [Nick Bostrom].
One of the most important tasks of Transhumanism is the
pursuit of Life Extension and eventual immortality, since
aging and death represents are two of the most immediate
hinders for total self-transformation and personal freedom.
Some members of these groups seem to regard aging as an inherited
disorder, and discuss 'curing' it - as though it is like any other
As I have previously argued in my
Adaptive Senescence essay, speaking of aging as an inherited
pathology is misleading and unhelpful.
Frankly, I don't see 'curing aging' happening.
Economics favours using parts which fail - primaily because they are
cheaper. The story of the Ford Model T illustrates this:
Henry Ford wanted to know which parts of his cars almost never wore
out. He found out what they were and directed his production staff to
make them cheaper so that they would wear out at about the same time
as the rest of the car, thereby making his cars cheaper to produce
while increasing his profits without decreasing the longevity of his
As for the "Morris Minor" appproach to aging - make everything as
modular and replaceable as possible - that too has some associated
costs. Modularity is an additional design constraint - and it
typically involves additional connectors and failure modes. The
associated costs typically have to be paid up front.
Perhaps curious scientists will eventually construct humans
which do not age. However, it seems unlikely that most creatures will
be built that way.
By analogy, scientists can construct coins which do not age - by
making them out of diamond. However, in practice few coins are made
Similarly, they can construct shelters which do not age - by making
pyramids. However, in practice few shelters are made that way.
Just because something is technologically possible, it doesn't mean
it will happen. Economic considerations may not favour it.
Selection favouring negligible senescence
Those organisms which exhibit negligible senescence seem likely to
have developed good repair strategies as a result of selection.
Several possible types of selective force could be involved -
selection may favour a very long lifespan if:
- You are rare and finding a mate is very difficult;
- You are large and development is very time-consuming (e.g. whale);
- You have a slow metabolism, due to resource scarcity (e.g. tortoise);
Humans are relatively large. But they already have long
lifespans for their size (perhaps due to the demands of parental care).
They do not score too well on the other factors which might favour
What natural selection favours is not the only factor
involved - since humans may use sexual selection and novel forces
such as directed mutation and intelligent design to
guide their evolution. However, natural selection will remain an
important force for some time to come.
I don't see much of a utilitarian case for 'curing aging'. It's all
very well to complain about the cost of building new libraries after
old ones have burned down - but it is important to realise that the
calculation involving weighing the costs of fireproofing against the
costs of fire is one that has already been done.
of course, if the cost of fireproofing - or the risk of fire - changes
radically, then that calculation may deserve reviewing.
Aubrey de Grey is a prominent proponent of the 'curing
I feel that saving lives is the most valuable thing anyone can spend
their time doing, and since over 100,000 people die every single day
of causes that young people essentially never die of, you'll save
more lives by helping to cure aging than in any other way.
Right - and I feel that devoting resources to curing aging
is typically largely a waste of time and effort - since
there are much more pressing problems than trying to make
humans which live for a very long time - such as irrigating
the world, dealing with pathogens and diseases, building
superintelligence, getting off the planet and making sure
we aren't wiped out by the first aliens we meet.
A fair bit of anti-aging research is likely to get done by
individuals with relatives at risk of age-related
disorders. No doubt they will make progress with their
mission to construct long-lived humans. However, I rather
doubt that governing bodies will be very interested in
funding this enterprise. Elderly organisms represent
reservoirs for pathogens - and alllowing them to persist in
the population may put large numbers of young, healthy and
productive individuals at increased risk of disease.
I suspect the enthusiasts promoting extreme longevity are
motivated by a desire for personal survival - or a wish to
exploit that desire in others - rather than out of genuine
Perhaps some really believe that the long-lived complex
organisms of the future will be close relatives of human
beings. However, I don't think this is very realistic: the
future dominant organisms will have software brains, not
the archaic wetware ones we currently have - and will
be descended more from our technology than our biology.
So resources spent on combatting human aging will make
little difference in the long term.
In the future some forces which have previously not been
very significant may contribute to the aging process:
technological obsolescence, protocol churn and fashion.
There is an whole essay dealing with those issues
Software hardware divide
An observation from computer science is that software often goes out
of date faster than hardware.
Fortunately, software is also easier to replace than hardware - and a
neat trick involving universal computers and a hardware/software
divide mean that they can be replaced independently.
This is one sort of modularity which I expect almost all future
dominant organisms can look forward to.
This may perhaps satisfy those who lament the loss of
brain-related information on physical death.
However it is only likely to apply to organisms with digital brains.
Rescuing some of the information in analog brains will be
done via computer input devices before analog brains are phased
Organisms with fuzzy boundaries
Discussions of senescence tend to assume there is a well-defined
organism with a known age involved.
While that is often true today, many future organisms seem likely to
be composite in nature - and different organs may have different
histories - and thus different ages.
Phenomena such as organ transplants seem likely to make discussing
senescence sensibly more difficult.
Machines and companies
The lifespans of machines and companies seem to me to be plausible
places to look when considering the lifespan of future dominant
The world's oldest company was recently liquidated - after surviving
for 1500 years.
However most companies and machines do not have anything like this
sort of lifespan.
The average car lifespan is about 15 years. The average company
lifespan is also about 15 years.
These are not exactly inspiring longevity figures. However, these are
early days for these types of creature.
Company senescence is discussed in more detail in my
Universal Senescence essay.
Around the time that metazoan calls clumped together to make
multi-cellular organisms they were time-bombed - so that elderly cells
were automatically destroyed. This prevented their malfunctioning from
damaging their associated organism.
Current policies allow the elderly to persist for as long as they can
feed themselves. Intensity of resource competition may make it harder
for the elderly to compete in the future. In the west, the current
taxation structure motivates many elderly organisms to distribute
their resources among their offspring and then stay alive for many
years - to avoid retrospective death taxes. If governments and
employers continue to fail to find value in the elderly, we may
eventually see the opposite situation: age-related taxes.
Future human lifespans
While some future dominant organisms may be large and complex - and
may thus have longer development cycles and long lifespans - these now
seem unlikely to be direct descendants of humans.
Even such large organisms seem likely to age. A number of theories of
aging seem likely to continue to apply to future organisms - including
major players - such as the disposable soma theory and
reliability theory. Also, a significant new cause of
aging - technological obsolescence - seems inevitable.
My best guess for the future of human lifespans is that they
will continue to increase modestly until about 2050 - and will then go
into decline. The decline will be concurrent with the human brain
being surpassed by the capabilities of computers. At around that point,
humans will begin to suffer from the effects of resource competition
with machines. The quality of life of most humans will
decline - and and humans will become increasingly like expendable
components in a large system.
Predicting future human lifespan is difficult - a few good plagues
might conceivably make a mess out of these predictions.
Technological development will mean it will eventually become
possible to effectively reverse most aspects of aging in organisms
genetically identical to modern humans - or to construct human-like
organisms which exhibit negligible not age.
However, these are non-trivial propositions. My guess is that by the
time they happen, humans are likely to be extinct.
- Henry Ford story
- The world's oldest company