Human ageing has not 'slowed' despite rising life expectancies, study suggests
Humans are not ageing any slower, despite our life expectancy rising over the centuries, research suggests.
The average British male dies at 79, while women generally live until 83.
Public health improvements, childhood vaccinations and the creation of the NHS are just some of the reasons why life expectancy almost doubled over 170 years.
In 1841, when the first "lifetable" was recorded, the average newborn boy lived to 40. Girls fared just slightly better, dying at 42.
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Life expectancy has since increased at a rate of around three months every year, with babies born in 2011 expected to live into their late seventies or early eighties.
It may seem as though ageing has slowed, however, scientists from the University of Southern Denmark have put this down to plummeting childhood death rates, which "brings up the average life expectancy".
The extent to which we can postpone our death has long been debated.
US scientists recently reported humans may be capable of living to 150.
According to the "invariant rate of ageing" theory, however, every species is only able to survive for a relatively fixed period of time.
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To learn more, the Danish scientists analysed how birth and death rates have changed across nine human populations.
They also investigated the varying lifespans of 30 non-human primates – including gorillas, chimpanzees and baboons – living in both the wild and zoos.
Results reveal a human's life expectancy – the average age an individual dies in a given population – increases alongside lifespan equality – a measure of how concentrated deaths are in older age groups.
Writing in the journal Nature Communications, the scientists explained how lifespan equality is generally high in developed countries, with most residents dying in old age.
In the 1800s, this equality was much lower, with deaths being less concentrated among the elderly.
More than one in 10 (15%) babies died before their first birthday in the 1840s, compared with 0.4% in 2011.
"Life expectancy has increased dramatically and still does in many parts of the world," said study author Dr Fernando Colchero.
"This is not because we have slowed our rate of ageing.
"The reason is more and more infants, children and young people survive, and this brings up the average life expectancy.
"Human death is inevitable.
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"No matter how many vitamins we take, how healthy our environment is or how much we exercise, we will eventually age and die."
The same pattern was also observed among the non-human primates.
"Not only humans, but also other primate species exposed to different environments, succeed in living longer by reducing infant and juvenile mortality," said Dr Colchero.
"This relationship only holds if we reduce early mortality and not by reducing the rate of ageing".
Nevertheless, science is advancing at an "unprecedented pace", suggesting it may one day be possible to reduce the rate we age.
"Not all is lost," added Dr Colchero.
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While a reduction in childhood mortality undoubtedly played a role, it may not have been the only factor behind rising life expectancies.
According to the Office for National Statistics, lower rates of tuberculosis (TB) – rife among children and adults in the 17th and 18th centuries – helped people live longer.
More women have also been surviving childbirth, and having fewer children, since the start of the 20th century.
Women have always lived longer than men, peaking at an additional 6.3 years in 1971. The gap has since narrowed, however.
Fewer men are working in the mining industry or other physical professions. Smoking, which has always been more common among men, has also declined.
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