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5 hours ago, Matt said:

Okinawan's start off almost half the level of DHEA and Testosterone (if I remember correctly) than Americans but it declines much more slowly. Eventually, Okinawan's end up with higher testosterone levels at older ages....

I haven't seen a mention of this anywhere, so if you could post a source, it'd be appreciated.

The Korean eunuch stuff is a very small sample, and frankly, not worth much, except as clickbait for the popular press. As it was pointed out at the time, it didn't take into account lifestyle or diet, and it was contradicted by most other evidence. I also posted earlier a fairly convincing study which strongly supports the theory that largely testosterone-driven risky behavior, rather than physiological reasons, account for much of the difference in lifespan between men and women (and the rest is likely mostly accounted for by the double X chromosome in women). 

Here is a good review of the consequences of castration in the major centers where the practice was found:
Long-Term Consequences of Castration in Men: Lessons from the Skoptzy and the Eunuchs of the Chinese and Ottoman Courts
"Indeed, there are no valid data indicating that castration has any effect on life span of men."
https://academic.oup.com/jcem/article/84/12/4324/2864451


Here is a mention of a very small study of castrati, which also didn't find much of a correlation with life span (mostly here as a rather interesting read):
"The effect of castration on lifespan has been debated. In a small study I did on 25 documented castrato singers born between 1610 and 1762 the mean lifespan was 65·1 years (SD 12·1) and was similar to that of 25 intact male singers born between 1605 and 1764 who lived a mean of 64·9 years (13·1) (unpublished). The relative longevity for this period may be explained by the fact that both groups lived fairly cosseted lives.is contradicted by Italian castrati studies."
https://www.usrf.org/news/010308-jenkins_lancet.html


There is also evidence that castration used to treat prostate cancer increases the likelihood of cardiovascular ischemic events.

Anyway, this is simply an attempt to counter likely erroneous assumptions about normal levels of testosterone being detrimental to longevity (and 412 ng/dL, while on the low side for 35, is within the normal range).

Edited by Ron Put

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I also ran across an interesting overview of another Blue Zone, Ikaria:

"In other studies, the metabolic syndrome (MetS) has been found to increase in prevalence among elderly individuals and seems associated with pathophysiological conditions that involve increased inflammation and oxidation process and mitochondrial and endothelium dysfunction. In previous studies testosterone levels have been found to be linked with cardiovascular health, as low testosterone levels seem to accompany aging-related diseases, like vascular dysfunction and atherosclerotic disease. In the IKARIA Study, the prevalence of MetS was associated with serum testosterone levels, only in men; at the same time, such relationship was not observed in women. Furthermore, serum testosterone levels were inversely associated with components of the MetS in both genders. When categories of lipids, hs-CRP, BMI, and insulin resistance levels were taken into account, testosterone lost its significance in predicting MetS, suggesting a mediating effect of these markers on the relationship between testosterone and the syndrome."
https://link.springer.com/referenceworkentry/10.1007/978-981-287-080-3_142-1

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16 hours ago, Matt said:

"Interestingly, out of the 81 eunuchs, three were centenarians, aged 100, 101, and 109 years. The current incidence of centenarians is one per 3,500 in Japan and per 4,400 in the United States. Thus, the incidence of centenarians among Korean eunuchs is at least 130 times higher than that of present-day developed countries."

This sentence captured my attention.

It doesn't seem to be a fair comparison, since it's a comparison by whole populations (Japan and USA) and a restricted sample. Even if we may consider the whole population of eunuchs, its numerosity would be hugely lower than that of the whole historical data of mortality (tens or hundreds of million data).

It's surely possible to apply a correction factor to the relatively small sample of eunuchs, but I wonder if the results would be statistically significant, moreover it seems that the life conditions were not equal, so the comparison would result to be biased a priori.

Edited by mccoy

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