The extent of human longevity, as it is now and what it might be in the future, remains a subject of scientific discussion. This to one side, a new study from the University of Southern Denmark explores our inevitable death.
Some people obsess over living for as long as possible and literature is full of tales of people seeking the key to human immortality. While steps can be taken to minimize the impact if disease and poverty, all humans die. Even when all possible risks are minimized, biological deterioration is inevitable.
In other words, humans, as well as other species, have a fixed rate of aging and eventual death. This remains relatively constant irrespective of how many vitamins are popped, how healthy a person’s environment is relative to another, or how much we exercise.
So, how long could lifespan become? Scientists in Singapore, Russia, and the U.S. estimate, using a biodemographic study, the maximum human lifespan as about 150 years (“Longitudinal analysis of blood markers reveals progressive loss of resilience and predicts human lifespan limit”). Whether this will come to pass remains to be seen, but only really matters if the majority of the population survive into this age, as the new research explains.
For the inquiry, researchers combed data of births and deaths patterns on nine human populations. This was examined alongside data gathered for 30 non-human primate populations, such as gorillas, chimpanzees and baboons, both living in the wild and in zoos.
The key points for the analysis were the relationship between life expectancy and lifespan equality (a measure of how concentrated deaths are around older ages). This revealed that as life expectancy increases, so too does lifespan equality. This means that when lifespan equality is high then it means that the majority of individuals within a given population will tend to die at around the same age.
This means that while life expectancy has increased in many parts of the world, this is not because humanity has slowed the rate of aging. Instead, it reflects more people surviving, which raises average life expectancy.
Hence, social policies aimed at achieving a reduction of infant mortality have accounted for most of the increased average life span longevity across time.
Across different periods of history, there has been a strong association between life expectancy and lifespan equality. This can be traced within pre-industrial European countries, hunter gatherers, to modern industrialize countries.
The study appears in the science journal Nature, titled “The long lives of primates and the ‘invariant rate of ageing’ hypothesis.”
