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Longevity Benefits / Drawbacks: Calorie Restriction vs. Sex Restriction (part 1)
Does restricting ones sexual drives--and that by itself--give Nature an excuse to keep you around a little while longer?
Here's an old study (1) that seems to indicate yes (a little), for male rats, anyway.
The studied parameters:
(i) diet [calorie] restriction by limiting access to food to 6.5 hr/day instead of 24 hr/day [not sure if this means these animals were ultimately CR'd];
(ii) housing males in a single-sex room as distinct from a mixed-sex room;
(iii) life-long segregation of males from females, as distinct from access to one virgin female for 5 days during each alternate week; and
(iv) uniparity in females versus life-long virginity.
Now, of course ;) !! "the results indicated major beneficial effects of dietary restriction on most of the endpoints" ... and "[b]y comparison the other variables had only marginal effects."
"Leydig-cell hyperplasia and neoplasia [cancer] occurred at significantly higher incidences [!!] in males housed intermittently with females than in permanently segregated males [not sure if males/females were allowed to interact; if not, perhaps there was pheromone-based "arousal" of free testerone ??]. No convincing differences were seen between females that littered once and those that remained virgins."
The effects of CR on libido are well-documented for humans (but, surprisingly, not much animal data here: mounting behavior frequency, etc.). And disposable soma (DS) is a credible theory. In any case, could one of CR's (sub-)mechanisms simply be a secondary effect of DS-based sex curtailment? Not much evidence for this, but (1) does raise some curiosity.
Please keep in mind that rats (all else being equal (AEBE)) are phylogenetically different from primates (2). Still, is there any relevance from (1) to humans? Wikipedia has a "list of noteworthy historical and legendary figures who have been famous for their virginity" (5). I Excel'ed the list for all males (not enough samples of females) which also noted birth/death dates (see below). The mean lifespan of 26 males was 71.53846154 yrs; the median lifespan was 78.00 years. Please keep in mind: these individuals were also higher-than-normal achievers (Newton, Kant, etc.) so, among other factors (socio-economic, etc.), the smart-people-live-longer theory may also be contributor.
What about the reports from a few years back which reported that longevous women have impaired fertility? These "predictions", notably by Westendorp and Kirkwood (4), were reexamined by Gavrilova/Gavrilova (3) who "found that most of these claims belong to obscure, poorly studied branches of genealogical trees rather than to well-documented families (kings, princes, counts, and earls)."
For humans, being highly-social creatures, the impact of sex restriction (be it CR-based or otherwise) and its impact on quality-of-life (QOL), happiness (and, hence, health) may be counter-productive.
The Abstract (1) terminates with: "The relevance of these findings to the prediction of cancer mortality risk in man and to the design of rodent carcinogenicity studies is discussed." Does anyone have the full-text paper (or any similar studies)? If you do, please contact me at firstname.lastname@example.org.
(1) Influence of food intake and sexual segregation on
Is There a Trade-Off Between the Costs of Reproduction and Longevity.
(4) Westendorp, R. G. J., Kirkwood, T. B. L. Human longevity
Aloysius Gonzaga 23
Avg (mean) = 71.53846154 yrs