How long can people live?

New study finds no evidence that maximum lifespan has stopped increasing
Higher IQ in childhood linked to longer life, air pollution associated with premature death

Is this the promised everlasting life? By analyzing the lifespan of the longest-living individuals from the United States (U.S.), the United Kingdom (U.K.), France and Japan for each year since 1968, investigators found no evidence for such a limit, and if such a maximum exists, it has yet to be reached or identified.

Emma Morano passed away last April. At 117 years old, the Italian woman was the oldest known living human being.

Super- centenarians, such as Morano and Jeanne Calment of France, who famously lived to be 122 years old, continue to fascinate scientists and have led them to wonder just how long humans can live. A study published in Nature last October concluded that the upper limit of human age is peaking at around 115 years.

Now, however, a new study in Nature by McGill University biologists Bryan G. Hughes and Siegfried Hekimi comes to a starkly different conclusion. By analyzing the lifespan of the longest-living individuals from the US, the UK, France and Japan for each year since 1968, Hekimi and Hughes found no evidence for such a limit, and if such a maximum exists, it has yet to be reached or identified.

Hekimi said: “We just don’t know what the age limit might be. In fact, by extending trend lines, we can show that maximum and average lifespans, could continue to increase far into the foreseeable future.” Many people are aware of what has happened with average lifespans. In 1920, for example, the average newborn Canadian could expect to live 60 years; a Canadian born in 1980 could expect 76 years, and today, life expectancy has jumped to 82 years. Maximum lifespan seems to follow the same trend. Hekim said it is impossible to predict what future lifespans in humans might look like. Some scientists argue that technology, medical interventions, and improvements in living conditions could all push back the upper limit.

He added: “It is hard to guess. Three hundred years ago, many people lived only short lives. If we would have told them that one day most humans might live up to 100, they would have said we were crazy.”

Also, a study published in The BMJ indicates that higher intelligence (IQ) in childhood is associated with a lower lifetime risk of major causes of death, including heart disease, stroke, smoking related cancers, respiratory disease and dementia. It is the largest study to date reporting causes of death in men and women across the life course, and the findings suggest that lifestyle, especially tobacco smoking, is an important component in the effect of intelligence on differences in mortality.

So a team of researchers from the University of Edinburgh set out to examine the association between intelligence test scores measured at age 11 and leading causes of death in men and women up to age 79.

Their findings are based on data from 33,536 men and 32,229 women born in Scotland in 1936, who took a validated childhood intelligence test at age 11, and who could be linked to cause of death data up to December 2015.

Cause of death included coronary heart disease, stroke, specific cancers, respiratory disease, digestive disease, external causes (including suicide and death from injury), and dementia.

After taking account of several factors (confounders) that could have influenced the results, such as age, sex and socioeconomic status, the researchers found that higher childhood intelligence was associated with a lower risk of death until age 79.

Also, a new study of 60 million Americans — about 97 per cent of people age 65 and older in the United States — shows that long-term exposure to airborne fine particulate matter (PM2.5) and ozone increases the risk of premature death, even when that exposure is at levels below the National Ambient Air Quality Standards (NAAQS) currently established by the U.S. Environmental Protection Agency.

The Harvard T.H. Chan School of Public Health researchers found that men, blacks, and low-income populations had higher risk estimates from PM2.5 exposure compared with the national average, with blacks having mortality risks three times higher than the national average. The results showed that if the level of PM2.5 could be lowered by just 1 microgram per cubic meter (ug/m3) nationwide, about 12,000 lives could be saved every year.

Similarly, if the level of ozone could be lowered by just 1 part per billion (ppb) nationwide, about 1,900 lives would be saved each year.

The study was published in the June 29, 2017 issue of the New England Journal of Medicine.