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Secondary ovaries = reproduction throughout life, good solution?

Discussion in 'World Building' started by caters, Mar 9, 2017.

  1. caters

    caters Sage

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    My Kepler Bb humanoids have 2 sets of ovaries. The primary and secondary ovaries though do different jobs when it comes to oogenesis. I know that human ovaries(and Kepler Bb humanoid primary ovaries) only have a finite amount of oogonia and all those oogonia turn into egg cells. This means that humans will eventually reach a point of menopause when becoming pregnant is hard to do 100% naturally. Postmenopausal pregnancy can happen but only with reproductive assist technologies like IVF. And after menopause there is a much greater chance of miscarriage because of low hormones.

    However, I think I have found a biological solution to this problem. My solution is to have oogenesis be more like spermatogenesis. I think the best way to achieve this is to have 2 sets of ovaries that are connected to each other via small tubes, kind of the female equivalent of a vas deferens. The reason I consider this to be a female equivalent is the fact that oogonia migrate to the primary ovaries and become mature egg cells in the primary ovaries.


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    If you look at this, oogenesis is like this in Kepler Bb humanoids except you get 1 egg and 3 polar bodies instead of 4 sperm. But there is 1 crucial difference between humanoid oogenesis and human oogenesis. That difference is the mitosis that goes on in the secondary ovaries. Oogonia are basically egg specific stem cells in humanoids whereas in humans it is just Interphase I. Without these oogonia being stem cells, these humanoids would have menopause. But because they are stem cells though these humanoids don't or at least shouldn't have menopause unless the secondary ovaries are gotten rid of via surgery. However, is this a good solution?

    To help you decide to see if this is a good solution here is another difference, my humanoids don't die of old age. They aren't completely immortal though. Any other cause of death in humans such as cancer is also a cause of death in humanoids. But because they don't die of old age, you could potentially have a completely healthy, 400 year old humanoid. Quadcentenarians would be rare though because usually disease, natural disasters, injury, or some other cause of death besides age would be there long before the humanoid reaches a century. However it could happen that some humanoid lives to 400 or even older, it is just rare. This doesn't mean that old age though is a cause of death for the reason I just described a few lines above.

    So since age for them is not a cause of death but every other cause of death in humans is a potential cause of death in humanoids, is my solution to pregnancy and menopause a good solution? It would mean potentially and probably in real life, more pregnancy mortality but it would also mean higher birth rates and higher pregnancy rates, both of which are good for establishing a population.
     
  2. elemtilas

    elemtilas Inkling

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    Two things here, one is the idea of senescent near-immortality and the other is staving off menopause.

    As for the latter, I don't quite think I understand how the two sets of ovaries overcome the issue. If I understand where you're headed with the oogenesis being more like spermatogenesis (where a girl would simply continue to produce egg cells continually throughout her life, the way a boy produces sperm continually), why would a second set of ovaries be needed? Are the second ovaries just the place where the egg cells migrate to for maturation? I think I'm missing something here.

    As far as the other thing goes, it sounds like not very many girls would even live long enough to take advantage of squeezing out babies in their three hundredth year of life! By that time, I'd think most humans would have succumbed to accident or disease. I don't know what the situation is in your world as regards medicine, but until the early to mid twentieth century, pregnancy was a leading cause of death for pregnant women! Infant and mother mortality rates alike were very high. And it's really only in the developed world where this situation has improved considerably to the point where most women don't even think about dying as a normal & not terribly unexpected (if uncomfortable) consequence of having a baby.

    How would a female humanoid even survive long enough to whip out thirty or forty babies before succumbing to some accident (breach presentation, placenta previa, etc), to say nothing of using her ovaries well into her tricentennial years?

    This is my solution to the problem, and you're certainly welcome to use it as food for thought or adaptation if you think it might work out for your humanoids:

    The Daine, like your humanoids, live long lifespans. A thousand years is typical, though unlike your humanoids, they don't suffer from cancer or infection or many other ailments that humans suffer from and they do not age the way humans do. That said, child birth is still fraught with danger, and maternal mortality rates, while nowhere near as high the human population, are still significant.

    Anatomically, Daine females seem to have a number of proto-ovaries set within their uterine cornua. As with other peoples, there are finite numbers of potential egg cells within any given ovary, and eventually the ovary will become empty of eggs. Whereas in a two-ovaried human, the resulting menopause means no more pregnancies. In a Daine, I think what's happening is the girl passes into a kind of refractory stage where she can't get pregnant, but this is only a temporary stage. After passing into this mini-menopause, she'll eventually pass again into a mini-puberty where the next set of proto-ovaries begin to awaken and produce a new cohort of eggs. This cycle will repeat itself until either she dies or runs out of proto-ovaries. The cycle itself seems to be something like twenty years on and sixty or eighty years off, meaning that after puberty, she's got twenty to perhaps thirty years where she can squeeze out her first cohort of children. After that, no more kids until quite a number of years later.

    I do know that as the "on" part of the cycle progresses, the number of children a girl could bear tends to wane: so, she could theoretically have one or two children a year for maybe ten years, then maybe one every other or every third year for the next fifteen, then maybe only one or two children the ten years following. (All timeframes approximate, of course.)

    Also, the number of theoretical children reduces as subsequent cycles are lived through. The second time around, a girl might only be able to produce twenty throughout the whole second cycle; then perhaps 10 and so forth.

    I also know that mid-"off"-cycle pregnancies can happen under extraordinary circumstances. Also, there are some véry rare cases of Daine girls who never cycle "off" --- they just burn through their series of proto-ovaries one right after the other.

    I don't know what the maximum number of proto-ovaries might be, but suspect it probably would not exceed eight sets. Just looking at the cycle lengths, that would allow for the possibility of pregnancy right into the ninth or tenth century of life.
     
  3. caters

    caters Sage

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    The secondary ovaries are where the oogonia split into 2 cells, 1 to become the next oogonium and the other to become a mature egg cell. The primary ovaries which are closer to the fallopian tubes are where the egg cells mature before ovulation.

    Medicine is actually pretty advanced for their technology level. They don't use epidurals during labor to lessen the pain, though they do massage the woman and pour warm water on her to partly relieve the pain, especially during early labor. They give ginger tea to pregnant women when they have nausea(first and third trimesters both) and if it is too severe, they can give a nutrient IV to the pregnant woman until the nausea subsides. After birth, they hold the baby by the placenta to get all the umbilical cord blood into the baby(takes up to 10 minutes before umbilical cord stops pulsating). Once the umbilical cord stops pulsating, they cut it and then have the newborn nurse as soon as possible after that.

    As for placenta previa, that usually resolves on its own by the 3rd trimester. As the uterus stretches out, the placement of the placenta changes, in particular, it rises. So it might completely cover the cervix in the first trimester and then partly cover it in the second trimester and then in the third trimester not cover the cervix at all.

    Placenta accreta, placenta increta and placenta percreta are a different story though. Placenta accreta where it just attaches to the uterine muscle but doesn't invade it might resolve on its own as the placental tissue becomes ischemic and falls out over the next few periods. Placenta increta and placenta percreta(uterine muscle invasion but not reaching outer layer and reaching the outer layer of the uterus, again it might resolve on its own as it becomes ischemic but it is much less likely than placenta accreta to resolve.

    Breach and transverse birth can usually be done vaginally, especially bottom-first breach. They avoid having the mom in certain positions for breach and transverse births.

    Any position that puts pressure on the back is not good for a breach birth. So the prone position(mom laying on her back during labor) is avoided.

    Any position that puts pressure on the sides is not good for a transverse birth so the positions for this are even more restricted than for breach.

    But for a normal vertex(head-first) birth, any position is fine.
     
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