Longevity and ftness

[wolfhnd]

Bio likes to contain speculation to personal theories so don't take my opinion as carrying any weight.

[Athena]

Okay, checked with the OP and see I got way off topic. This thread isn't about aging in general but a specific, menopause. So back on topic- this link might be better.

http://www.medscape.com/viewarticle/866931

Of the 16,251 women, 8892 (55%) survived to age 90 years. Women who started menstruating when they were at least 12 years old had slightly higher odds of longevity (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.00 - 1.19) than those who started before age 12 years. Those who had a later age at menopause (natural or surgical; Ptrend = .01) were significantly more likely to live longer, with ORs of 1.19 (95% CI, 1.04 - 1.36) and 1.18 (95% CI, 1.02 - 1.36) for ages 50 to 54 and at least 55 years compared with less than 40 years, respectively.
"Longer reproductive lifespan was significantly associated with increased longevity (Ptrend = 0.008). The odds of longevity were 13% (OR 1.13; 95% CI, 1.03-1.25) higher in women with more than 40 compared with less than 33 reproductive years," the authors write.
Findings were independent of lifestyle behaviors, body mass index, reproductive factors, or past oral contraceptive or hormone therapy use.

Possible Reasons for Link
Several factors may help explain the associations, the authors note.
Early menstruation has been linked to higher risk for adult obesity, diabetes, and cardiovascular disease (CVD). Later menopause and longer reproductive years also have been linked to decreased CVD risk.
Women who started their periods and entered menopause at a later age were also less likely to be smokers or have a history of age-related diseases.
"It is also possible that the association of later age at menopause with longevity may be partly explained by lower odds of survival due to comorbidities and adverse health status among women who experienced premature menopause, irrespective of the cause," the authors write.
A common set of genetic factors may also play a role.
"For example, a genome-wide association study of age at natural menopause identified genetic variants involved in DNA replication and repair pathways, which are pathways central to aging," the authors write.
One limitation of the study was that authors did not have information on family history of longevity, occupation, stress, or diet, which may also predict longevity.
Future studies will be needed to better determine mechanisms for the link between longevity and the biological events....

This link also applies

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3287288/

Ages at menarche and menopause have been shown to be associated with adverse health outcomes in later life. For example, earlier menarche and later menopause have been independently linked to higher risk of breast cancer. Earlier menarche may also be associated with an increased risk of endometrial cancer, menstrual problems and adult obesity. Given the associations of ages at menarche and menopause with future health outcomes, it is important to establish what factors across life, and generations, may influence these. This article examines the associations of early life factors, namely birthweight, bodyweight and growth during childhood, childhood socioeconomic circumstances and psychosocial factors with ages at menarche and menopause. It examines possible explanations of the associations found, including life history theory, and discusses areas for future research.

[Athena]

There may be a connection between diet and longevity that also applies to early menarche and menopause, so my previous links are not totally off subject.

The energetics theory suggests that energy availability during childhood influences the timing of menarche. It hypothesizes that girls who were exposed to a chronically poor nutritional environment will grow more slowly, experience later pubertal development (relative to their genetic potential), and reach relatively small adult size compared with those children who were exposed to greater food availability. This is consistent with an earlier idea regarding the impact of relative fatness that follows from the close relationship of average critical bodyweight on age at menarche [23]. http://www.medscape.com/viewarticle/866931

I think we need to look at energy and how our bodies are aware of energy reserves and also how this relates to free radicals. There must be an adequate store of energy to reproduce, and accumulated free radicals that are also related to stored energy bring on death.

[wolfhnd]

I'm taking a break for a while Athena will comment some other time. Thanks for participating, catch up with you later.

[SciameriKen]

My Feeling on the evolution of menopause is that it is probably contingent on the grandmother effect - i.e. that a grandmother not able to rear *new* children of her own could then assist in the raising of *her children's* progeny - thus increasing the fitness of the menopause "gene". Figuring out how a specific pleitropic entity evolves though is extremely difficult and in my opinion, its fun to speculate but we'll likely not arrive at the answer.

Still - my speculation is that menopause arrises in species with high childbirth mortality - as the likelihood of producing healthy offspring declines with age, menopause could provide a survival benefit, and further, if the mother dies after several children, the grandmother would probably be more successful at raising the progeny to reproductive age than random strangers. But again, there could be many many factors so who knows :D

[zetreque]

Are there any experiments to detect if menopause happens earlier or later in women under certain conditions?

[SciameriKen]

Are there any experiments to detect if menopause happens earlier or later in women under certain conditions?

I don't know if that is the correct experiment to tease that out - Poor conditions may become good conditions, thus one would not want to induce permanent menstral cessation because of a bad spring only to see a great spring the next year. And again this is just speculation and probably more relevant for larger mammals. Mice also go through menopause at about 12-16 months of age, yet in the wild these creature probably wouldn't last longer than 3-6 months. So my only guess there is menopause evolved in a common ancestor under conditions that are no longer important for a mouse.

[zetreque]

What about an experiment where they have a group of mice in a strong family environment and another group in a broken family. With replication.

[SciameriKen]

What about an experiment where they have a group of mice in a strong family environment and another group in a broken family. With replication.

I think it will be a difficult experiment with too many confounders to observe the desired effect. But let me know what you are thinking exactly for this - what would the experiment look like? As in what are the investigators doing to the mice during this experiment? (Removing parents?). What outcomes are you looking for? What is your hypothesis?

[zetreque]

Speaking of mice. Looks like I have my first candidate. Just saw one running across the back room. First one I have seen here since living in this place for the past 12 or so years. Everyone this year has been talking about outbreaks in mice due to the extreme water winter we had I assume. Got the trap set.

[wolfhnd]

I will eventually get back to this topic.

[Athena]

Much research has already been done on mice. You might begin with this google page...
https://www.google.com/search?rlz=1C1CH ... fUBCPMBMBY

[Athena]

Are there any experiments to detect if menopause happens earlier or later in women under certain conditions?

Yes, the cause of early menopause has been studied.

http://www.healthline.com/health/menopa ... #overview1
Causes
There are several known causes of early menopause, although sometimes the cause can’t be determined.

[BioWizard]

Biowizard

I know you have an interest in aging. In another thread we are discussing why animals live past the age where they are fertile. My guess is that it is related to the need to slow aging in species that have extended pregnancy and infant care. If it takes a number of years to raise offspring to semi independence longer life spans may be advantageous. That would however not explain long life spans in species such as parrots. In some species longer life spans may result from low birthrates and high infant mortality. The two concepts are of course not mutually exclusive.

Your thoughts please.

I honestly don't think there are any simple answers that can be mathematically formulated in the form you are thinking. I think ageing rate, menopause, reproductive strategy, should be thought of exactly the way we think of all other phenotypes (e.g. anatomical features, metabolic rates, etc). They evolved and co-evolve, responding to selective pressures or just neutrally, and interact with the constellation of other phenotypes and survival strategies that each species is experiencing. My 2 cents.