Dr Irengbam Mohendra Singh
HG Wells who began writing science fiction novels since the 1909s, called them “fantasias of possibility”. Most of them indeed turned out to be real science. I think life of any person is “fantasy of the certainty of death”.It has a potentially dangerous moral arc, about acceptance and its comeuppance, happiness and its sad end.
But, do we have to die? No, we don’t have.Growing old does not increase your immediate risk of dying – at least, if you are a fruit fly (see below).
Death is only an evolutionary phenomenon – not an inherited trait. Benjamin Franklin famously wrote, “In this world, nothing is certain but death and taxes.” AsI’ve always said there is no death gene in the human genome, and life isn’t programmed to end with death.There’s nothing in biology that indicates the inevitability of death. Death can be hastened say, by suicide or murder, or poor diet. It can be postponed with good living and better medical care.
There has been many research in experimental gerontology whether or not there is a genetically defined limit to human lifespan. If the answer is no, and the results of study in fruit flies apply to humans, old people now can live indefinitely.
In 1825, the British statistician, Benjamin Gompertz formulated an empirical law stating that mortality rates of all species, increase exponentially withage.This is known as Gompertz Law.In 1979, James Vaupel of Duke University, North Carolina (US) and his collaborators in Denmark, analysedcensus data from 18th-century Lutheran church records in Scandinavia. Their result contradict the Gompertz Law, but instead, it levels off.
As a doctor, I know old age is mainly the direct cause of death as systems that run the body fail eventually, because of anatomical, chemical and physical deterioration, or diseases that are the main cause of death at any age. As we get old (65+) our resistance to infection and cancer is quite low. Among the important causes of ageing are “senescent cells”. These are cockeyed cells, which build up as we age, damaging the tissue, producing inflammation and exhaustion of stem cells. But the bodily changes and environmental issues differ from one individual to the other.
If modern science were to prevent all the diseases that kill people, the dateline of death for most old people could, if not for ever, be quite distanced. It’s estimated that roughly 150,000 people die each day in the world, and about two thirds of it—100,000, die of age-related causes – some diseases, accidents and the ageing process itself.
Richard Feynman, the most distinguished American theoretical physicist, died of cancer in 1988. He was 70 years old. He said, “We only need to look back at the wager you and your buddy made over the beginnings of life on earth [after the Big Bang] to remember that just because something has never happened does not mean that it never will happen. Things change, and while life on earth was a non-thing for a billion years or more, at one point it became a thing. Change is one thing that is truly inevitable. If life can start from no life, what’s to say that life won’t someday figure out how to not die? We need dread the former a little less fiercely. This suggests to me that it is not at all inevitable and that it is only a matter of time before biologists discover what it is that is causing all the trouble leading to death.”
A research published in the journal Science in June 2018, led by statistician Elisabetta Barbi from the Sapienza University, Rome in Italy, claims to have addressed the question of the inevitability of death. She says, “The increasing number of exceptionally long-lived people and the fact that their mortality beyond 105 is seen to be declining across cohorts […] strongly suggest that longevity is continuing to increase over time and that a limit, if any, has not been reached.”
Scientists have known for quite some time that hypothalamus, an almond-shaped structure in our brain controls ageing. They have observed in mice that,stem cell transplantation in the hypothalamus could speed up, or its depletion could slow down ageing.Research showed that, in mice that normally live for about two years,a specialized group of stem cells began to disappear by about 11 months. By 22 months, they had vanished completely. The rate at which the stem cells was lost closely correlated with ageing changes in the animals, such as decline in memory, decreasing muscle endurance and energy deficit.
Some other scientists,seem to have discovered a new distinct phase of life, the fourth phase of life, which heralds the approach of death. This stage of life they call a “death spiral”.The research was done with fruit flies (vide infra).
Just before 1990s, biologists thought that life has two main and distinct phases only: childhood and adulthood.Childhood is characterised by rapid growth and development, and ends with sexual maturity. During this phase, the probability of death is extremely low.When adult life starts after teenage years, married with children and a regular income, we are on the highest peak of life span – the middle age. Thereafter we begin to age. Our activities in life slow down as our bodies begin to deteriorate. The probability of death increases with passing years, first slowly and then faster and faster, ending up caput.
By the 1990s,scientists have recognisedthat life has another part, a third phasethrough which the oldest members of our society go through: the late life. In this late phase of life, the structure of mortality is quite different from the previous two phases of life. While ageing is commonly associated with exponential increase in mortality with age, mortality rates paradoxically decelerate in the late life, resulting in distinct mortality plateaus (no changes). Though death can occur at any time, theimminent death at 60 is higher than 50, which is late adult life; and at 70 higher than at 80. Thereafter the chance of dying between 90 and 100 is the same ie the mortality rate flattens out (plateau).
Scientists have been trying to find out if there is a statistical limit to human lifespan, using common fruit flies (Drosophilamelanogaster). Fruit flies share 75% of the genes that cause diseases in humans. Understanding of modern genetics would not be possible without the humble fruit flies. They live on rotten fruits that begin to ferment producing alcohol, which attracts them. During the process they also lay hundreds of eggs, which will hatch to larvae in a few hours. They are thus very useful for biological research. In 1947, they were the first to go to space on a rocket and return alive with a parachute. NASA sent a bunch of them in 2017, to the International Space Centre to study the effect of zero gravity (weightlessness) on heart.
In 1996, Laurence Mueller of the University of California and his colleague, have been studying fruit flies for biological features that might lead to death of animals. “There is no known cause for this mortality plateau.We thought that there may be the same circuit that carries the reproduction or female fertility (fecundity).”
“I noticed that if I separated out the females that were close to death, and compared them to other females of the same age that I knew from the dataset, still had several more weeks to live, there was a difference in the fecundity. Put simply, a fly’s fertility rate – the number of eggs she laid per day – plummeted in the two weeks before she died,” says Mueller.
They thought humans might experience it too. Mueller and Rose said that it was a universal feature of life, a new fourth phase that is different from the childhood, adult or late life. They called
it the “spiral of death”. Later, they found that the males of Drosophila were also undergoing a similar decline in fertility a few days before death. “As soon as the male gets older, its ability to impregnate females is getting worse and worse,” But when males are going to die at any age, their ability to reproduce was much lower than males of the same age, who lived for a few weeks more,”says Mueller.
Few other scientists confirmed Mueller’s findings. Among them, James Curtsinger from the University of Minnesota conducted his own experiments in the field of aging and death. He found a decrease in fertility in anticipation of death, which generally correlates with the findings of Mueller and rose.But he says, “Plateau of mortality is not a feature of old age, it can appear in the middle or at a young age.”
Debates continue though the General consensus currently is that a plateau of mortality is associated with old age.ButI fear the fourth stage of life is a long and slow decay before death. No sweat. Before scientists find out how to live forever, there should be more research on how to live fit and healthy until you die.
Gautama Buddha, who hated old age, was lucky to dieat 80 after eating pork and without suffering the ‘fourth stage’ of old age, (cf. Buddha’s Last Meal by EF Thomas).
The author is based in the UK Email:email@example.com Website: www.drimsingh.co.uk