Will we be immortal by increasing our life expectancy?

Pieter van Lint - Allegory of immortality

This method is based on the following idea: if we could manage to increase our life expectancy by more than one year per year, we would automatically be immortal. Mathematically, this idea is correct. But is there any chance that it will happen in practice?

One problem is that the increase in life expectancy is slowing down, and has even reversed.

First, we must clear up a misunderstanding. Two completely independent concepts should not be confused:

• Life expectancy: This is a relative concept, which depends on the age. Thus, the life expectancy of someone who has turned eighty is much less than that of a newborn child. The data usually given is life expectancy at birth. With the medical revolution from the 19th to the 21st centuries, life expectancy at birth has risen. But its growth rate, instead of accelerating, has slowed down, and lately it has even gone down.

Year	Country	Life expectancy	Increment (years/year)
1950	Norway	71,6
1960	Norway	73,6	0,04
1970	Sweden	74,7	0,16
1980	Island	76,5	0,34
1990	Japan	79,0	0,24
2000	Japan	81,2	0,30
2010	Japan	82,9	0,18
2015	Hong-Kong	84,3	0,28
2019	Hong-Kong	85,3	0,10
2020	Hong-Kong	85,2	-0,10
2021	Hong Kong	85,5	0,30

The attached figure shows the evolution of life expectancy at birth in the United States during the 20th century and part of the 21st. It is clear that the maximum increase took place between 1930 and 1950. Since then, it has been declining, and several times it has stalled.

• Longevity: This is the maximum duration of the life of an individual belonging to a given species.
• In unicellular beings, the concept of longevity does not make sense, because they do not age: when they reach a certain size, they split in two or more identical cells and go on living indefinitely. Also the concept of individual does not make sense, because we would not know which of the descendants takes away the individuality of the mother cell.
• Plants, especially some species of trees, have the longest longevities of multicellular beings, reaching thousands of years.
• Among animals there is a bit of everything: some (such as sponges and coelenterates) resemble unicellular beings; others (such as platyhelminthes and echinoderms) have enormous regeneration capacities, and if they are broken into several pieces, each regenerates an independent individual; others (such as vertebrates) reproduce sexually and the concept of an individual is well defined: each individual ends its life by aging and dying. Turtles seem to have the longest longevity, reaching 150 years. They are followed by man. There is no reliable evidence that any human being has lived much more than 120 years. Other mammals have much lower longevities than man.

With the medical revolution from the 19th to the 21st centuries, human longevity has not increased. In fact, it’s probable that it hasn’t grown a single year during the entire history of mankind: there have always been a few individuals who got to be 100 years old. In consequence:

To achieve immortality, increasing life expectancy is not enough; longevity must also be increased.

If longevity is not increased, as soon as life expectancy at birth approaches maximum longevity, life expectancy will stop growing.

Will we be able to increase our longevity? We will come back to this in the next post.

The same post in Spanish

Thematic Thread on What is Immortality?: Previous Next

Manuel Alfonseca