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No Ground for Advocating that Korean Eunuchs Lived Longer than Intact Men

2015; Karger Publishers; Volume: 62; Issue: 1 Linguagem: Inglês

10.1159/000435854

1423-0003

Éric Le Bourg,

Birth, Development, and Health

Dear Sir,Explaining the differences in life span between men and women is a recurrent topic in the gerontology literature. One of the hypotheses relies on sex-linked endocrinological differences, and some authors thus wonder whether castrated men could live longer than intact ones because of a lower production of testosterone [1,2,3,4,5]. For instance, a recent article in Gerontology stresses that 'some evidence - not the strongest evidence, however - supports the hypothesis of the life-shortening impact of men's hormones' [5].Recent articles have relied on a study reporting that Korean eunuchs lived longer than intact men [6], but this study cannot be used as an argument for a longer life span in eunuchs. The intent of this letter is to warn colleagues against citing this source as a possible explanation for a gender-linked difference in life span.In this study [6], the authors compared the life spans of eunuchs and intact men living at the time of the 'Imperial court of the Korean Chosun Dynasty (1392-1910)' by relying on a genealogical record of Korean eunuchs, the Yang-Se-Gye-Bo, and confirmed the validity of these records 'by cross reference to the Annals of the Chosun Dynasty and Diary of the Royal Secretariat'. However, we ought to doubt the exactness of the reported life spans for several reasons. Firstly, the records report the existence of three centenarians (dying at 100, 101 and 109 years of age) in a sample of only 81 eunuchs. As emphasised by the authors themselves, 'the incidence of centenarians among Korean eunuchs is at least 130 times higher than that of present-day developed countries', and this is really surprising. Secondly, it is an extraordinary fact that a longevity of 109 years was observed in a man living from 1784 to 1893 [[6], table S2]. Indeed, living to 109 years is very close to the highest longevity records ever observed in men, i.e. 115 years (see some examples in Maier et al. [7]). Even though the authors assert that they verified the data based on a second source, the fact remains that, for example, this second source only shows that the 109-year-old man was alive 63 years before his alleged death. Thus, this second source is not sufficient to confirm the first one, and the study of a subsample of the 81 eunuchs (n = 48; fig. 1) [[6], supplemental information] shows that the interval between the last recorded observation of a eunuch and his alleged death can span several decades. Thirdly, demographers have established strict criteria for validating the longevity of centenarians and supercentenarians, i.e. people living beyond 110 years of age, and this study on eunuchs hardly satisfies the lowest level of certainty [8], i.e. 'date and age at death without verification'.To tell the naked truth, one cannot rely on this study of Korean eunuchs in the absence of confirmatory information coming from other sources than the genealogy of eunuchs. This is in sharp contrast with the validation process of the life span record of Jeanne Calment, who died at 122 years of age [9] (see other examples of life span validation in Maier et al. [7]). The Bolivian Carmelo Flores was reported to have lived longer than Jeanne Calment, as he was alive at 123 years of age in 2013, but this was based only on a parish register reporting his birth in July 1890. This man, if born in 1890, was, according to him and press releases, a soldier in 1933 during the 1932-1935 war between Bolivia and Paraguay (43 years of age), and his last child was born when he was 56 [10,11]. Most probably, a mistake altered '1908' or '1913' into '1890' and he was a soldier in his twenties, his last child being born when he was around 30 years, as it happens for most of men.Explaining differences in life span between women and men is currently impossible, and a sensible hypothesis could be that hormones come into play. However, testing this hypothesis by relying on eunuchs requires good data. A previous study in mentally retarded men had shown that eunuchs lived longer than intact men, but 44% of the deaths of the intact men were due to infection (27% of the eunuchs), particularly tuberculosis, and thus were not linked to the ageing process [1]. Another historical study, based on biographies of castrated singers, did not show any differences from intact singers [2]. Both studies are vulnerable to criticism, and it is probable that it will remain impossible to prove that eunuchs live longer (or shorter) than intact men in the absence of appropriate and verified data. In any case, it is better to conclude that 'we do not know' when, in fact, data cannot be checked.