Perspectives in Biology and Medicine

PUZZLES IN LONGEVITY CYRIL A. CLARKE* and URSULA MITTWOCHf Royal Demographer Following the example of her predecessors, Queen Elizabeth II is accustomed to send telegrams of congratulations to those of her subjects who attain their hundredth birthday. Some years ago, on hearing that the number of centenarians had greatly increased in all developed countries , one of us (C.A.C.) wrote to the Queen's secretary for details. The reply, received almost by return of post, contained the information that the number of messages sent to centenarians in the United Kingdom was 300 in 1955, 1,200 in 1970, and 3,300 in 1987. The royal information is likely to be an underestimate because it is dependent on a relative or friend of the celebrant communicating the impending birthday to the queen. More complete figures for England and Wales are available from the Office of Population Censuses (OPCS). While numbers of centenarians obtained directly from census returns are thought to be exaggerated, more reliable figures are based on information obtained from the Department of Social Security. The OPCS estimates tell us that the number of centenarians has risen from 27 1 in 1951, and 2,410 in 1981 (J.A. Rowntree, personal communication), to about 4,500 in 1991 (R.I. Armitage, personal communication), a sixteenfold increase in the last forty years. During the same period, the total population increased from 44 million in 1951 [1] to 51 million in 1991 [2], i.e. by a factor of 1.2. Almost 90 percent of the centenarians were women. The authors are indebted to J. A. Rowntree, formerly of the OPCS, and to R. I. Armitage , Population Estimates Unit, OPCS, for information about centenarians; to Professor Stephen Evans for discussion; and to Lady Clarke for invaluable assistance. They also acknowledge the receipt of a Leverhulme Emeritus Fellowship, and an Auber Bequest from The Royal Society of Edinburgh (to U.M.). *Department of Genetics and Microbiology, The University of Liverpool, Donnan Laboratories , Box 147, Liverpool, L69 3BX, United Kingdom. !Department of Anatomy, Queen Mary and Westfield College, Mile End Road, London El 4NS, United Kingdom (correspondence address).© 1994 by The University of Chicago. All rights reserved. 0031-5982/94/3703-0865$01.00 Perspectives in Biology and Medicine, 37,3 ¦ Spring 1994 327 In other countries the picture is very similar. Among twenty-eight developed countries during the 1980s, male life expectancy at birth varied between 65.1 years in Hungary and 74.8 years in Japan, and the corresponding female life expectancy between 71.4 years in Venezuela and 81.4 years in Hong Kong [3]. Three other countries—Japan, Iceland , and Switzerland—had female life expectancies above eighty years, and the difference between male and female life expectancies varied between 3.3 years in Israel and 8.3 years in Finland. Japan has seen a dramatic rise in life expectancy, to the extent that Japanese babies can now expect to live longer than anyone else in the world [4]. At the same time the gap between male and female life expectancies has increased even further: at birth, from 4.2 years in 1955 to 5.7 years in 1986 and, during the same period, at age 65, from 2.3 to 3.4 years. We are thus faced with two problems: to explain, first, the massive increase in longevity, and second, the equally striking bias in favor of women. External Factors Affecting Longevity It is self-evident that the arrival of antibiotics has increased longevity by counteracting potentially fatal infectious diseases, and the same applies to beta blockers in relation to cardiovascular disease. The efficacy of growth hormone in reversing some of the adverse effects of old age is presently being tested [5, 6]. There is less inbreeding than in earlier generations, resulting in improved hardiness. An important factor in the reduction of inbreeding was the invention of the internal combustion engine, which brought about a choice of marriage partners from within a larger area. This was further augmented by the breakdown of strict codes of conduct. For instance, in Japan cousin marriages used to be common, largely because the exchange of expensive presents made it necessary for partners to...