Demarrek19871

Evolutionary Mechanisms/Driving forces for the Evolution of Menopause

Women go through menopause about half way through their lifespan. Because humans, killer whales, and pilot whales are the only species confirmed to go through menopause there are a number of hypotheses about why this occurs. Demarrek19871 (talk) 23:31, 28 February 2016 (UTC)

Reproductive Conflict Hypothesis/In-Law Competition
Reproductive senescence coincides with the age at which reproductive competition from younger females would begin. While post-reproductive survival can be selected for to help a woman's own children reproduce, it is argued here that kin-selected fitness gains do not outweigh the potential gains of continued reproduction. Kin-selected benefits explain post-reproductive survival but not early reproductive senescence . The reproductive conflict hypothesis suggests that menopause is the outcome of reproductive competition in generations within social units and is complimentary to the Grandmother Hypothesis.Demarrek19871 (talk) 23:31, 28 February 2016 (UTC)
Another related theory is the In-law Hypothesis. When women and their mother in-law had children within two years of each other had reduced infant survivor-ship by 50% . However, there was no decline in survivor-ship when women and their own mothers had children at the same time. The decline in infant survivor-ship is hypothesized to have driven the evolution of menopause. It would have been adaptive for women to stop ovulation before their daughter's in-law began to have children and therefore the small reproductive overlap is the result of previous stabilizing selection pressures . One potential issue with the in-law hypothesis is that the study was conducted using data from a relatively non-migratory population, as compared to our by majority hunter-gatherer ancestors.Demarrek19871 (talk) 23:34, 28 February 2016 (UTC)

Change in Mating Behavior Hypothesis
This non-adaptive hypothesis suggests that at some point in time, there was shift in preference for younger females or that younger females were out competing older females for mates. If there was a population that was long-lived and able to produce throughout their lifetimes, then gender specific mutations that diminished fertility late in life would be selected against. However, this proposed change in mating behavior would result in only young females reproducing thereby reducing the natural selection on older females . With relaxed natural selection on older females, the mutations reducing fertility would become neutral, allowing them to accumulate and female fertility would thus decline with age. This hypothesis suggests that this accumulation of now neutral mutations would gradually result in the evolution of menopause. When using computer models to explore the hypothesis, it was also found to be true if only young males mate, resulting in male menopause . Demarrek19871 (talk) 23:31, 28 February 2016 (UTC)

Primary Sources:
http://www.pnas.org/content/105/14/5332.abstract

Secondary Sources:
http://blogs.scientificamerican.com/primate-diaries/a-grimm-tale-of-reproductive-conflict/
http://www.nature.com/news/in-law-infighting-boosted-evolution-of-menopause-1.11253
http://www.the-scientist.com/?articles.view/articleNo/37153/title/Putting-the-Men-in-Menopause/
Demarrek19871 (talk) 20:08, 25 February 2016 (UTC)

What's on Wikipedia already and what's missing

the Wikipedia page already has quite a bit of information on menopause already. The page kind of starts out with a basic clinical description and then goes down through talking about:

• -premenopause/Sx of menopause transition
  

• -Tx options
  

• -details of the transition in a general summary sense
  

• -Premature Ovarian Failure and Surgically induced menopause and what the causes/effects are for each
  

• -the biology of menopause (I feel that we ought to go ahead and fact check some of this and make sure there isn't anything to add)
  

• -Ovarian aging
  

• -diagnosis and stages of menopause (Some detail could potentially be added here)
  

• -details of Tx options
  

• -Evolutionary mechanisms of menopause (The intro to the topic could probably be fleshed out)
  

non adaptive hypotheses (there's not a lot of detail here)

adaptive hypothesis (only the mother, grandmother, and "survival of the fittest" hypotheses are discussed in this section 
so we could add about the other hypotheses discussed in class as well as new hypotheses that we find in our online research)

• -presence/absence of menopause in other animals (this section is pretty brief as well but I so far haven't found any other info to contribute beyond what is already written) Demarrek19871 (talk) 19:46, 25 February 2016 (UTC)