Biogerontology 1: 371–372, 2000. © 2000 Kluwer Academic Publishers. Printed in the Netherlands.

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Correspondence

Gerontologists and the media: false hopes and fantasies can be hazardous for science ´ Le Bourg Eric ´ Laboratoire d’Ethologie et Psychologie Animale, FRE CNRS no. 2041, Universit´e Paul-Sabatier, 118 route de Narbonne, F-31062 Toulouse cedex 4, France (e-mail: [email protected]; fax: +33-5-61556154) Received 15 May 2000; accepted in revised form 29 May 2000

Key words: gerontology, human longevity, media Dr de Grey (2000) strongly disagrees with my Opinion article published in the first issue of Biogerontology (Le Bourg 2000). His main argument is that an over-pessimistic attitude toward ‘engineered negligible senescence’ (ENS) may be detrimental to gerontology as well as a too optimistic attitude. To support his opinion, de Grey criticizes my views about the prospect for a 150 year median longevity in 2100. In this answer, I shall give some comments about that point and, after that, I shall express my opinion about the core of de Grey’s letter.

The 150 year median longevity in 2100 De Grey considers that a 150 year median longevity in 2100 does not necessarily mean that we shall observe a median age at death of 150 years in 2100. When using the term ‘median or mean longevity’ I had in mind, as most people I guess, life expectancy at birth. For instance, life expectancy at birth of women in France was 82.3 years in 1999 (Kerjosse 2000). Rather, de Grey considers that the common sense is “the mean age of death of those alive in 2100”. This would mean that we have to record the age of death of persons living in 2100, and thus to wait more than 100 years to know the longevity of people born in 2100. Thus, “the mean age of death of those alive in 2100” would not be known before 2200, at least. Clearly speaking, most people seem to consider that a 150 year median longevity in 2100 means exactly what it means: life expectancy at birth, which is computed in most countries every year and commonly used by newspapers and broadcasting networks.

De Grey considers that I have used only one means to increase the median longevity, namely the decrease of the mortality rate doubling time (α), while it could also be possible to decrease the ageindependent mortality rate coefficient (A). This is correct. I followed Finch and Pike (1996), who stated that reaching a median longevity of 120 years could be possible by decreasing α by 45% or A by 98%. However, these authors added that “reductions of A by 98% seem less attainable in human populations . . . because of general risks of accidents that are irreductible even under the best conditions” (p. B186). In such conditions, I chose not to modify A in the computation. In a last criticism, de Grey states that “it is mathematically inevitable . . . that we will eventually achieve a 150-year mean longevity” and that “a mathematical certainty is not a hypothesis”. If the possibility of a 150-year mean longevity, one day, was relying only on mathematics or technology I would agree with de Grey. When focusing on technological challenges, the main problem is usually money, not time: only a few years were needed for the USA to walk on the Moon after the decision to spend money to do it was taken. But, the 150-year mean longevity relies on biology. Up to now, no human being has reached the age of 150 years or beyond and nobody can prove that it will be possible. It is a curious rationale to assess that due to a continuous increase of scientific knowledge, this goal may be reached. It could be, but it could be not: for many centuries cattle breeders have selected for an increased milk production but cows are still cows and it is impossible to transform them into a milk factory, even if we may

372 have no doubt that modern geneticists would like to do so.

False hopes and fantasies I agree with de Grey “that many people want to see ENS develop and to benefit personally from it” and that “there is no clear moral, social or political argument against such technology”. This is true since the beginning of times. It is also true that at each historical period, some persons claimed to have found the secret of aging (ENS?) and tried to sell it. What is new nowadays is that people know they will live for a long life, when compared to previous decades, and that a very few of them hope that modern science will help to live for a still longer time, and maybe for ever. This is exactly the point where these people and modern charlatans meet. Thus, I strongly disagree with de Grey when he writes that “supplements which increase lifespan in model organisms can reasonably be hoped to increase one’s own, and thus one’s chance of surviving until ENS arrives”. This speech clearly means: 1) buy products to, probably, increase your lifespan; 2) one day, and not at the end of times since you will be still alive, ENS will, probably, come to save you. Since we do not know whether “supplements” increase human lifespan and if ENS will come one very next day, this kind of sentence can give a bad impression of gerontology to people. People could rightly conclude that, after the yogurt, the vitamins, the cell transplantation, and many other life elixirs, scientists claim to soon discover the true secret of aging. It could be argued that the question of ENS is not if it will come, but when it will come. It could be right, but I have the strong feeling that if you tell to a journalist that ENS will be available in, say, three centuries, there is no chance he will find some interest in that information, since all readers of the newspaper will be dead at that time. By contrast, if you make the same prediction for the next decades, there is a higher chance for your photograph to be on the cover page. I am afraid that telling to media that ENS could come soon may give false hopes, and despair when it will be obvious that ENS is still a dream. We

cannot afford that risk, due to the incautious attitude of many past gerontologists claiming to have discovered the way not to age. Some people are so afraid to age and to die that they are ready to believe any story which could help them to decrease their fear. We know that charlatans make a good use of this fear to sell their products and it is our responsibility not to help them in any way. Some colleagues could consider that ENS is not a fiction and that, some day, it will be as common as today’s antibiotics. It could be. But, suppose you live during the XVIIIth century. What would you think if a well-known scientist would tell you that it is indeed possible to resist to infections, while at the same time some people are selling products they claim to help you resist to infections? Since at that time antibiotics did not exist, you would probably conclude that this well-known scientist offers a guarantee to charlatans, even if he does not agree with their trade. Therefore, it seems better to wait for a clear proof of feasibility of ENS before claiming that ENS could exist in the next future. Otherwise, we are at risk to be the puppets of charlatans. When it will be proved that Peter Pan has actually existed and was able to fly without using any machine, it will be an information and probably the end of planes. But, for the time being, it is a nice fairy tale for our children before they go to bed.

Acknowledgements Many thanks are due to Tom Kirkwood and Suresh Rattan for their comments on a first draft of this letter.

References Finch CE and Pike MC (1996) Maximum life span predictions from the Gompertz mortality model. J Gerontol Biol Sci 51A: B183– B194 de Grey ADNJ (2000) Gerontologists and the media: the dangers of over-pessimism. Biogerontology 1: 369–370 (this issue) Kerjosse R (2000) Bilan démographique 1999. Hausse de la fécondité et recul de la mortalité. INSEE Première, no. 698 Le Bourg É (2000) Gerontologists and the media in a time of gerontology expansion. Biogerontology 1: 89–92