divulgatum está dedicado a la difusión de conocimiento científico en español e inglés, mediante artículos que tratan en detalle toda clase de temas fascinantes pero poco conocidos.
divulgatum is devoted to the dissemination of scientific knowledge in Spanish and English, through articles that go into the details of all sorts of fascinating, if not
widely known, subjects.

Friday, July 23, 2021

On eternal life

(Image credit: Francis C. Franklin/Wikimedia.)

I WAS WALKING along a canal in Cambridge, when I stopped to watch a moorhen and its young chick. They were swimming among the branches of a small fallen tree. The moorhen dived briefly to pick one of the tree’s seedpods; the chick dashed as lightning to devour it. I thought of how both of them were oblivious to anything that had ever been, and anything that was yet to be. Their attention was devoted entirely to this thin slice of life. The adult moorhen was oblivious to the fact that it must die in a few years, if not sooner; the chick ignored that it would very soon be feeding its own progeny. Yet I could see this all too clearly. The chick was but a young version of its parent, and was to be an old version of its own offspring, and would then cease to be. I could see this process unfolding backwards in time through millions of repetitions, as more and more remote ancestors of the moorhen slowly shifted in shape to resemble early birds, then dinosaurs, then amphibians, then fish, then simpler organisms, down to the one cell whose genetic material now inhabits every life form. It was the evidence of this endless natural cycle of existence which doubtlessly inspired the idea of spiritual reincarnation, on which the weight of so many human religions rests.

We humans lie in a strange place in the path of life. An immensely long process of evolution connects us to the first self-replicating cells that came into existence over three billion years ago. As life became able to build biochemical systems of higher complexity, a certain kind of self-awareness gradually emerged, from the rudimentary proprioceptor systems of microorganisms, to the evident understanding of their own existence which animals (and even plants) display, and then to the capacity of higher animals for conscious decision-making. Then came Homo sapiens, an overbrained primate that is not only aware of its own existence, but is also able to ponder deeply about it, pose questions about the world it inhabits, and speculate on the causes and meaning of its own life. Humanity marks the point where life stood up, looked back upon its own wake, and was left speechless by its own inconceivable magnificence. We are the only form of life capable, to any extent, of understanding what life is. And yet we are subject to the same cycle of birth, reproduction and death. We reincarnate ourselves in our children, imperfect copies of us who, like the moorhen’s chick, are bound to retrace the arc of our own lives, make imperfect copies of themselves, and finally perish. Our children will admire the descendants of the birds we admire today, and history will keep passively unfolding, while we convince ourselves that life revolves around the infinitely short slice of time which we happen to inhabit. By understanding this, we have perhaps come as close as it is possible to grasping the endless miracle and the infinite calamity of our existence.

It is the ceaseless replication of every organism which makes life immortal. Because every living being must inevitably die, be it from predation, disease, or mere accident, the genetic information that allows life to function cannot rely on a single vessel. Life’s vessels must be such that they are able to construct brand-new vessels before succumbing to any of the natural forces which conspire against their existence. Like infinitesimally short segments of an unfathomably long pipe, we transmit the precious information of life to its new recipients, unintentionally ensuring that life itself carries on after we have been pushed off the stage. Vessels make new vessels; proteins and lipids are created, degraded, created again; only the information of life, written in DNA, survives forever. After our own death, every product and every memory of our life will inevitably dissolve in the vastness of time, whether it takes one generation or one hundred. But our genes, and the genes of our parents, our ancestors, our children, may live as long as humanity does.

Our species also holds a special place for a different reason. Even if Homo sapiens were to become extinct, as have the vast majority of species which have ever existed, life itself will certainly persist, in one form or another, until the Sun’s death throes transform our planet into a ball of molten rock, billions of years into the future. The end of the Earth will mark the end of terrestrial life, and no trace whatsoever will be left of its long and grand history. For even though life possesses the instruments to withstand the unrelenting destruction of its vessels over eons, it is entirely unprepared for such an extreme prospect. Among the many millions of living species, only ours has become aware of it. And so, as life which is conscious of itself and of its destiny, only we can avert the ultimate ending of life, by carrying it to a new planetary vessel. Although the idea of colonising planets outside our own solar system is still an utterly unrealistic one, the fact remains that, unless another species of comparable or superior intelligence emerges in the far future, this will be the only opportunity for life to survive the death of our planet. Whether humanity will ever be in a position even to consider embarking in this ultimate task of self-replication, only time knows. By then, you will have finished feeding your children, and you will no longer exist; perhaps your children and grandchildren will have ceased to be; but the information which you all carry will still inhabit self-conscious vessels of flesh and blood, driven by new thoughts, new hopes, new feelings. This is eternal life.