Longevity Benefits / Drawbacks: Calorie Restriction vs. Sex Restriction (part 2)The "fact" that life-shortening effects of normal sexuality has apparently been documented in disparate species (rats (0) and fruit flies (1)) is, in my opinion, noteworthy. But there is not enough empirical data to come to any definite conclusion (hint, hint: universities and researchers!) In humans, the benefits of restricting/delaying sexual activity may, in part, be a population-specific response rather than a universal effect: "[Sami] females who produced their last offspring at advanced age also lived longest, while age at first reproduction and total fecundity were unrelated to female longevity. Our results thus suggest that reproductive and somatic senescence may have been coupled in these [note: THESE, i.e. Sami] human populations, and that selection could have favoured late reproduction." (2) Other factors, such as the sex of the offspring, may also be at work: "... in preindustrial humans, the number of sons delivered reduced expected maternal longevity, whereas the number of daughters raised improved it." Perhaps because "pregnancies with male fetuses are associated with elevated maternal testosterone levels. Testosterone is an immunosuppressor and may thus play a role in accelerating immunosenescence and consequently decreasing the survival into old age of mothers who have born several sons." On the other hand, these studies report ... "...our results are in agreement with several studies that report no phenotypic trade-off between fecundity and longevity in humans." (4) ...or: "...from age 70 onward late mothers age at a lower rate. This may be the result of both biological and social factors." (5) My "gut's" telling me that like CR, O2 restriction and mild sleep restriction, sex restriction (SR) probably has some benefits. SR may, however, be harmful if it fundamentally decreases QOL, leading to unwanted, chronic stress. Personally, (and since entering the hard-core CR zone -- i.e., very low calorie intake) I have experienced huge relief from drive-related emotions of jealousy and "competitiveness". But my preferences may be rare, even for CRONies. Back to Calorie Restriction vs. Sex Restriction (part 1) References: 0. Influence of food intake and sexual segregation on longevity, organ weights and the incidence of non-neoplastic and neoplastic diseases in rats. Food Chem Toxicol. 1990 Jan;28(1):39-48. PMID: 2138115 1. Influence of sexual activity on longevity in adult male Drosophilia
melanogaster.
C R Acad Sci Hebd Seances Acad Sci D. 1977 Jul 18;285(3):233-5. French. 2. Are reproductive and somatic senescence coupled in humans? Late,
but not early, reproduction correlated with longevity in historical Sami
women.
Proc. R. Soc. B (2005) 272, 29–37, doi:10.1098/rspb.2004.2944 3. Sons Reduced Maternal Longevity in Preindustrial Humans 4.
Human longevity and early reproduction in pre-industrial Sami populations.
J. EVOL. B IOL. 15 (2002 ) 803–807 2002 BLACKWELL SCIENCE LTD |