Introduction: Cancelling the Debt The DebtThis book is inspired by the possibility of human life extension. Developments in a number of scientific disciplines suggest that we may soon be able to increase life expectancies from the seventy- to eighty-year range now seen in the richest countries to well over a hundred and, perhaps, to over a thousand. We shall, in one sense, have made ourselves immortal. We shall not be immortal in the sense that we cannot die; plainly we could still be killed in a car accident or by a cosmic event such as an asteroid striking the earth. But we could not be killed by disease or age, our bodies would be immune to infection, dysfunction or the ravages of time. We would be medically immortal.Some say this will happen quickly - within, perhaps, thirty years with the first clear signs that we are on the right track appearing within the next decade. Others think we are at least a century or two away from attaining medical immortality.

Some consider it completely unattainable. But the majority of scientists and thinkers in this area now consider life extension and even medical immortality possible and likely. Not long ago, most would have said it was out of the question, that death at or well before the absolute maximum age of something like 122 was inevitable. (That was the age at which Jean Louise Calment died on 4 August 1977. She has the most credible claim to be the longest-lived human ever, almost all other claims having been discredited. Maria Olivia da Silva, a Brazilian, is said to have been born in February 1880, but, so far, this has not been verified.)The basis of this shift from unattainable to feasible is not generally understood. It involves a transformation in our conception of human biology and an expansion of our capacity to intervene in its workings that may yet prove to be at least as momentous as the discoveries of Copernicus, Galileo, Newton, Darwin or Einstein.

I shall explain this scientific transformation in some detail in Chapter Two.But Copernicus to Einstein is not the only tradition that is at issue here. There are also the traditions that run from Buddha to Mohammed and from Plato to Wittgenstein, the traditions of religion and philosophy. Our relatively brief lives and our routine proximity to the deaths of ourselves and others are the foundations of everything we have ever thought or believed. Neither religion nor philosophy necessarily promises immortality, but each offers ways of coming to terms with or giving meaning to death and, therefore, life. If death is to be postponed indefinitely, then both religion and philosophy face fundamental crises.Of course, many other traditions - of politics, art, commerce and culture - are also at stake. In truth, it is difficult to think of any aspect of human life that would not face similar crises.

What, for example, would be the meaning of the greatest works of the human imagination to a medical immortal? Shakespeare's sonnets may be said to be about the brevity of life and the painful transience of human love and beauty. But if we lived for a thousand years or more in a condition of youthful health and vitality - the postulated life-extension technologies promise to hold us permanently in our late twenties - then would we come to see these poems as the curious remnants of an antique world rather than urgent expressions of the deepest truths of our predicament? Would any art of the past survive this revolution with its dignity intact? Would there be any art of the future?Many may think that, as they suffer from no illusions, fantasies or sensitivities, new life-extension technologies are nothing but good news, simple additions to the portfolio of benefits delivered by modern technology. But their worlds are also threatened. For example, the language of relationships is the vernacular of our contemporary, secular life. What would our precious relationships look like to medical immortals?.