Longevity and Purpose

I foresee a not-too-distant future in which humans will live to 200, 300 years, maybe more. Advances in medical science, in particular our understanding of the genetics of ageing, will be the main driver. Humans are believed to have a genetically determined age limit of around 115 years; break through that barrier (to do with telomeres) and longevity can be increased greatly. But not all humans will be destined to live spectacularly long lives. Longevity has its genetic factors, but the environmental ones - where we live and how we live - make a huge difference. And inequality in income and wealth will be mirrored in longevity outcomes as the rich spend an increasing part of their money on staying healthy longer. But while most of us will be living longer - some of us a lot longer - there will be fewer of us. Fertility rates are falling - globally.

Background

Human population is expected to peak in 2064 at 9.7 billion before falling to 8.8 billion by the end of this century. The populations of  Japan, Italy, Spain and South Korea are expected to halve by 2100; China's will nearly halve to 730m, leaving India as the most populous nation on earth - and Nigeria at number two with a population of 791m. Even as fertility rates across the developed world plummet, in the emerging economies populations will continue to grow, though at a much lower pace.

Women, with access to education and birth control, will be in control of reproduction rates. And increasingly in the developed world, worries about climate change, environmental and social anxieties are putting many women off having children altogether - motherhood has become a lifestyle choice rather than a matter of biological predetermination.

Fewer people will lead to an improvement in the quality of life. The median age will extend. Progress in technology will lead to less-stressful and more meaningful work as the drudgery of repeated (white-collar at least) tasks. We'll be able to work longer without considering it an imposition.

Environmental factors

The death of Japanese doctor Shigeaki Hinohara at the age of 105 three years ago prompted many articles in the world's media about his secrets of longevity. The key, he said, was having a sense of purpose to life, to know why you get up each morning. He kept working into his final years. Also crucial is daily exercise (our hunter-gatherer ancestors walked 12 miles/20km a day on average, more than twice as much as I do). We should restrict our eating ("All people who live long - regardless of nationality, race or gender - share one thing in common: None are overweight," he said).

(Factors are many however. On reading his Wikipedia page, I discover we share the same birth date - 4 October, though 46 years apart. I suspect that historically, children born in the early autumn may have had a natural advantage; their mothers in later pregnancy had plentiful access to fresh seasonal fruit and vegetables and sunlight. That advantage may have been eroded by year-round access to seasonal produce thanks to globalisation and air freight, but this may change.)

We shall see rising inequality in longevity outcomes. The less intelligent will die sooner. Worse diets, less willpower to exercise, worse living conditions, greater propensity to take life-threatening risks, a lower propensity to follow commonsense healthy-living guidelines. But more of them will be born. The intelligent will in general have fewer offspring. This was the premise behind the 2006 sci-fi comedy film Ideocracy. Set in 2506, the intelligent have died out, unwilling to reproduce, while the morbidly stupid procreate with thoughtless abandon.

I can see, however, an exception. Those educated folk, like the Rees-Moggs (six children) who will choose to bring many children into inherited wealth for ideological or religious (or both) reasons. This could be the start of a divide in human evolution into two biologically distinct species, slim, intelligent, long-lived overlords and overweight, dim serfs who only live to 70 or 80.

My innate optimism is losing its sparkle.

This time two years ago:
New bus stop for Karczunkowska

This time eight years ago:
Who should pay for railways?
[Interesting stuff about America's advanced electric railway line over the Rockies - built over 100 years ago!]

This time ten years ago:
Grunwald - the big picture

This time 12 years ago:
"Take me right back to the track, Jack"

This time 13 years ago:
The summer sublime