Future senescence


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 universal.

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.
- [http://www.aleph.se/Trans/Individual/Life/]

Some members of these groups seem to regard aging as an inherited disorder, and discuss 'curing' it - as though it is like any other genetic pathology.

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 cars.

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 that way.

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 negligible senescence.

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 aging' business.

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.

- [http://www.sens.org/concerns.htm]

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 utilitarian concerns.

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 here.

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 out.

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 organisms.

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.

Colonial aging

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.


  1. Henry Ford story
  2. The world's oldest company

Tim Tyler | Contact | http://alife.co.uk/