John Bateson

The 2022 UN Population Forecast published last week looks at longevity. Global life expectancy at birth reached 72.8 years in 2019, an improvement of nine years since 1990. Average life expectancy is forecast by the UN to reach 77.2 years by 2050. Still an improvement but at a declining rate. Absolute declines are not unknown. Sub-Saharan African had the HIV epidemic . Fortunately life expectancy is now bouncing back. Eastern Europe suffered a health crisis after the dissolution of the Soviet Union. Even now the US life expectancy is declining through the combined influence of the opioid crisis and obesity.

Women live on average longer than men by 5.4 years globally. Observed in all regions of the world. The UN is still projecting continued longevity growth for both sexes. They predict that by 2050 a 65 year old can expect to live and extra 19.8 years. This is up from 17.5 years in 2019. This comes from better treatment of non-communicable disease and other chronic conditions. These include diabetes, cancer, and chronic respiratory disease.

A Continuing Trend?

Life expectancy has risen in a straight line by three months per year every year since 1840. This unbroken trend had existed for one hundred and eighty years. For every year we age we are only approaching death by nine months. It was discovered by researchers from Cambridge University and the Max Plank Institute. They found eight countries around the world that had collected data since 1840. They ranged from Australia and New Zealand to Norway, Sweden and Switzerland. Longevity was growing in a straight line consistently everywhere.

Many people have predicted a limit to this life expectancy improvement. They start from the premise that the human body has a finite life, so the trend cannot continue. So far, each attack on the trend has been proved wrong within five years of it being made. Longevity continues to grow in that linear fashion.

We have to remember that these numbers are averages. Average longevity can go up without individuals living any longer. Life expectancy improvements have been fuelled by different age groups at different times. A recent study looked at thirteen developed countries. They all have been on the longevity journey since the nineteenth century.

Between 1850 and 1900 sixty two percent of all improvements in life expectancy came from the Under-15 age group. Only three percent of the improvement coming from those above sixty-five. The impact on the average life expectancy of saving the life of a one-year-old is larger than that of saving a sixty-year-old. An infant will add (say) 70 years to the total, a sixty- year- old perhaps only 10.

In the period 1925-1950, the under fifteens still accounted for thirty one percent of longevity improvement. This is before the massive improvements that came with vaccination for childhood diseases such as polio, whooping cough, mumps, and measles. Instead the improvements came from upgrades in nutrition and public health. Medical science has blossomed in a single generation. When my father was seven, he was placed in an isolation hospital far from his parents. At that time, there was no treatment for a child killer known as scarlet fever. I have the letters my grandfather wrote to him every day. He recovered after three months alone. Today scarlet fever is treated easily with anti-biotics.

During that period Governments also gave considerable emphasis to safety regulation. This reduced adult accidental death. As Pinker in his book Enlightenment put it:

“Over the course of the 20th century, Americans became 96 percent less likely to be killed in a car accident, 88 percent less likely to be mowed down on the sidewalk, 99 percent less likely to die in a plane crash, 59 percent less likely to fall to their deaths,93 percent less likely to die in a fire, 90 percent less likely to drown, 92 percent less likely to be asphyxiated , and 95 percent less likely to be killed on the job”

After that the emphasis shifts to people who are over fifty. The under fifteens only contributed six percent in the period 1990-2007. Seventy nine percent of the improvement came instead from the those over 65. Medical science has increasingly focused on this group. Indeed, forty two percent of the total improvement came from the over eighty age group.

All this underpins that 3 month per year improvement in longevity. In some countries of Europe and North America progress in life expectancy is already slowing or stalling. This happened before the outbreak of COVID. As improvements have come from older age groups there have been diminishing returns to average life expectancy. Child mortality in Europe is only 3.4 deaths per 1000 live births, leaving little room for further improvement.

Where will be the new sources of improvement?

One clue comes from the latest UN report. In 2021, the disparity between the highest and lowest country level life expectancy was 33.4 years. The highest countries were Australia, Hong Kong and Japan. They averaged 85. The Central African Republic, Chad, Lesotho and Nigeria averaged 54 years. This is due to persistent high levels of child and maternal mortality. Life expectancy across all the least developed countries lagged seven years behind the global average. Even within Europe, Moldova and Russia are at 70 years whereas Switzerland is at 84.

We can improve averages by levelling up disparities. We have solved child mortality in many parts of the World. Why not in Nigeria or Chad? In previous Newsletters I have shown that disparities do not just exist between countries. There are huge variations within countries. The gap between deprived and affluent areas can be huge. There is a ten year difference in life expectancy between the bottom and top decile in the UK. In the USA there is a 14.6 year gap in life expectancy between the top 1% and the bottom 1%.

A Drug Breakthrough

Eric Verdin heads the Buck Institute in California. It is biomedical research institute dedicated to the study of ageing. It has twenty one labs each dedicated to a different approach. These range from computational biology to “nutrition and exercise”. He argues that we are at the point of a breakthrough in two areas. The first is “regenerative medicine” . This focuses on curing the declines that come with age. Finding the cures for chronic illnesses such as macular degeneration. The second is the research stream focusing on the extension of human life itself. He has a wonderful quote on the Buck Institute website:

“Science is showing that while chronological aging is inevitable, biological aging is malleable. There is a part that you can fight, and we are getting closer and closer to winning that fight.”

We inherit only 20% of our prospective longevity. The rest is environmental. Over the last ten years ageing research has identified many pathways to attack the ageing process. At a conference he was asked how long it will take to start extending life expectancy. He pointed out that there were drugs already starting the medical approval process. the problem is that it can take up to eight years. However there are a whole plethora of already approved drugs that are thought to have a positive impact on aging. He described an informal survey of all of the medical researchers that he knew. He asked whether they were self-experimenting with life extending drugs. He found many were and as he put it “they were looking good on it”!