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Why can’t women get pregnant without the menstrual cycle? (2016)
- diN0bot 9y agoperhaps the most gripping read of any hacker news post ever. seriously entertaining and informative!
- lordleft 9y agoSeriously! This was unbelievably compelling!
- tomp 9y agoI wish I had teachers like this. I found most of history, most of my primary and high school (i.e. several different teachers) excrutiatingly boring. Then I read a book on the economic history of the world that didn't just present raw facts, but also why things happened (i.e. stories) and it was one of the most interesting things I've ever read!
- hi41 9y agoWhich book on economic history was that?
- tomp 9y agoI've no idea. It was short, probably less than 50 pages, covered the period since about 1500. A friend sent me a .pdf but I can't find that email, or the pdf, I've tried searching before.
- hi41 9y agoYes, I know that feeling. I had This is Water essay by David Foster Wallace in an email and I couldn't find it and the page I had bookmarked was gone too. I was so upset. The essay keeps coming back in my thoughts.
- jcfrei 9y agoAgreed. This one and the earlier article "War in the womb" posted in 2014 (https://news.ycombinator.com/item?id=8155153 https://news.ycombinator.com/item?id=8155153) fundamentally changed my understanding of pregnancies.
- csours 9y ago>"Researchers, bless their curious little hearts, have tried to implant embryos all over the bodies of mice. The single most difficult place for them to grow was – the endometrium." Whoa...
- astrodust 9y agoIt's the thunderdome, but not as bad as a shark uterus. They generally only give live birth to one shark because that shark has eaten all the others.
- nasredin 9y agoAnd sharks including threshers, makos and great whites have an even odder solution: They feed their fetuses an endless stream of unfertilized eggs. 2. Sibling cannibalism Sand tiger sharks have the most ghoulish fix for hungry babies: The fetuses devour each other in-utero until there’s just one pup remaining in each of their twin wombs. This uterine bloodbath is thought to have developed because a litter of sand tiger pups usually has multiple fathers — and each dad is engaged in a proxy war for his genes to take the upper hand. The “winning” fetus gets all the nutrients from its siblings and a roomy womb to develop into an unusually big baby, over 1 meter (3 feet) long at birth. Being born large and well-developed helps these newborn predators survive in a hostile ocean.
- burfog 9y agoMy first thought was right on top, in various layers: skin, fat, muscle, etc. Nope. They did the brain, testis, spleen, liver, and kidneys.
- DogOfTheGaps 9y agoFascinating. Reminded me of the The Selfish Gene, especially the part discussing the opposing objectives of the mother and offspring.
- spectrum1234 9y agoYes. Amazing book. The Red Queen as well.
- Ygg2 9y agoThe Selfish Gene isn't wrong, but its not true either. It's true your genes exist in you, and they generally evolve to survive. However, "Selfish" genes can do some rather unequivocally selfless things. E.g. symbiosis.
- lukas099 9y agoSymbiosis isn't exactly selfless; it benefits both organisms involved. Even if you mean altruism though, a gene for altruistic behavior can still be selfish. For example, if Gene X causes an organism to sacrifice something for another organism that carries also carries Gene X, the gene will be promoting its own survival.
- Ygg2 9y agoIt's not exactly selfish either. You realize there is a benefit to cooperation. Most cell organelles are product of symbiosis.
- mtgex 9y agolukas099 is arguing one of the central points of the book, that altruistic behavior is inherently selfish on a genetic level. You seem to be arguing completely based on the title of the book, which itself makes clear that the title is provocative but not entirely accurate, which makes me think you have not read it.
- 9y ago
- deleted 9y ago[deleted]
- tetrazine 9y agoVery interesting answer from Suzanne Sadedin. Very odd that "Arush Kakkar, Founder, CorsecoTech", who appears to neither be a physician, nor a medical science expert, nor a woman, is the highest displayed answer for me, with a strained analogy relating women's bodies to software, which is based on Suzanne's answer. I don't know if this is because of user voting, his score, or the Quora algorithm. I wonder if the mysteries of this ranking system are what lies behind the Quora login wall.
- elil17 9y agoSadedin's post has over 20k upvotes, but that guy has 81. Definitely not because of user voting.
- nostrademons 9y agoIt's fallen to #2 now. I would bet it's recency bias; that guy is probably there from this Hacker News link, made a follow-up answer, and because Quora (like HN and many forums) tends to put new replies at the top to give them a chance & see how they do with voting, it momentarily showed up as the top answer.
- raldi 9y agoQuite the opposite; his answer was from Jan 2015; the good answer arrived nearly two years later.
- nostrademons 9y agoI'm not terribly familiar with Quora's UI, but it looked like that's the date that the person's author profile was last updated, not the date that they answered the question. I could be totally wrong on this though. It's not possible for the good answer to have arrived later, because the bad answer references it (unless he edited the post afterwards to refer to it, but if the date on the post is actually a last-edit date for the post, that still wouldn't make sense).
- madethemcry 9y agoI first wondered if OP means that first answer with the obscure and horrible programming analogy then I found the real answer by Suzanne Sadedine which is an amazing read. That was the creepiest part: Some fetal cells find their way through the placenta and into the mother's bloodstream. They will grow in her blood and organs, and even in her brain, for the rest of her life, making her a genetic chimera and this is a wonderful summary of evolution: In other words, it's just the kind of effect natural selection is renowned for: odd, hackish solutions that work to solve proximate problems
- mirimir 9y agoThat is an amazing explanation of primate pregnancy and menstruation. Another extremely creepy aspect is how the placenta burrows into the endometrium. It sounds a lot like tumor angiogenesis, doesn't it? Indeed, the fetus sounds like the alien ones in Alien. An unwanted fetus is rather like an attacker. Especially in light of conflicting selection pressure.
- newnewpdro 9y agoFunny that you should mention tumor angiogenesis. Two of my female friends were diagnosed with Uterine Fibroids [1] in their 30s, and both their doctors said basically the same thing in recommending hysterectomy - paraphrasing: "The uterus is good for two things, growing babies and growing tumors." Apparently these are extremely common, and hormonal birth control exacerbates the problem by making the body behave as if it's constantly pregnant. Both of my friends were angry about having been casually prescribed birth control pills as teens without being clearly informed of it increasing the probability of this outcome. [1] https://en.wikipedia.org/wiki/Uterine_fibroid https://en.wikipedia.org/wiki/Uterine_fibroid
- ShabbosGoy 9y agoIntuitively, it makes sense. Life and growth are inextricably linked, as are death and destruction. Unrestricted cellular growth leads to cancer/tumors, unrestricted cellular destruction also leads to cancer, but of autoimmune origin.
- randyrand 9y agothis BBC article disagrees: http://www.bbc.com/earth/story/20150420-why-do-women-have-periods http://www.bbc.com/earth/story/20150420-why-do-women-have-pe...
- nostrademons 9y agoIt actually supports pretty much all of Dr. Sadedin's details if you read past the first half of the BBC article, which describes previous discredited theories.
- ec109685 9y agoThat article was better than the OP, given it is less of a narrative and instead presents how research and theories have evolved over time.
- simonblack 9y agoStrictly speaking, they can. The period occurs at the end of a cycle, so it's possible to get pregnant on your very first cycle without ever having had a period. The likelihood of this happening is extremely low of course.
- imron 9y agoStrictly speaking, the question is asking why women can't get pregnant without the menstrual cycle. As you mention in your post, the period occurs at the end of the cycle, therefore without a cycle, pregnancy will not happen.
- mirimir 9y agoNo. Menstruation occurs if there's no implanted and viable fetus by ~24 days after ovulation. A few days later, ovulation occurs, and the cycle repeats.
- newfoundglory 9y agoWhat are you saying no to?
- mirimir 9y agoMaybe I read it wrong. Pregnancy and menstruation are alternate endings for the cycle. So, as GP said, a woman could theoretically get pregnant on her first cycle, without menstruating.
- newfoundglory 9y agoI think you are agreeing with the comment you responded to.
- mirimir 9y agoMaybe so. Too late to delete.
- teekert 9y agoDid anyone get a pop up on the page saying the page was "reestablishing internet connection, click here". I clicked but immediately felt pretty stupid, I never just click on things but this was so... normal. And why would a page and not the browser report this?
- abhishek0318 9y agoPerhaps, linking this post to this link would be better: https://www.quora.com/Why-do-women-have-periods-What-is-the-evolutionary-benefit-or-purpose-of-having-periods-Why-can’t-women-just-get-pregnant-without-the-menstrual-cycle/answers/4625918 https://www.quora.com/Why-do-women-have-periods-What-is-the-...
- dang 9y agoOk, we changed to that from https://www.quora.com/Why-do-women-have-periods-What-is-the-evolutionary-benefit-or-purpose-of-having-periods-Why-can%E2%80%99t-women-just-get-pregnant-without-the-menstrual-cycle?share=1 https://www.quora.com/Why-do-women-have-periods-What-is-the-.... Thanks!
- blattimwind 9y agoEven Wikipedia describes placentation like a siege: > The trophoblast, which is a collection of cells that invades the maternal endometrium to gain access to nutrition for the fetus, proliferates rapidly and forms a network of branching processes which cover the entire embryo and invade and destroy the maternal tissues. With this physiologic destructive process, the maternal blood vessels of the endometrium are opened, with the result that the spaces in the trophoblastic network are filled with maternal blood; these spaces communicate freely with one another and become greatly distended and form the intervillous space from which the fetus gains nutrition.
- deleted 9y ago[deleted]
- nishagarg 9y agoUmmm.. someone I know did not have the menstrual cycle (had for only 2 initial years) but she still has 2 kids healthy and fit.
- cornholio 9y agoArtificial wombs can't happen soon enough, it's the final challenge to equal rights.
- photonios 9y agoWhat a brilliant piece of writing! Very compelling.
- danieltillett 9y agoWhile the post was very entertaining, it did not actually answer the question. We don't know why higher primates (and bats) have periods.
- vanillaboy 9y agoHappy it wasn't just me left wondering what that answer was all about.
- bpicolo 9y ago> The solution, for higher primates, was to slough off the whole superficial endometrium Doesn't that suggest that's reason for higher primates? Or are you disagreeing with the author of that post?
- danieltillett 9y agoThis is the hypothesis, but no evidence to support this theory is advanced. We don't know that higher primates (and bats) have more aggressive embryogenesis than other animals that don't have periods.
- jessaustin 9y agoMice and rats are an interesting case, since they have hemochorial placentae but not menstruation. This somewhat undercuts TFA's "this because of that" narrative. (Really the only flaw in a wonderful article.) Evolution is weird.
- cooper12 9y ago> This somewhat undercuts TFA's "this because of that" narrative. (Really the only flaw in a wonderful article.) You're underselling this flaw, because it's fatal. A major issue with a lot of pop science is this exactly: the author is much too confident in connecting disparate ideas (because it serves good storytelling and increases trust in the author), when in actuality it's very dangerous to assign intent to things like evolution. For example, a common statement you hear is "evolution caused..." Evolution doesn't have a will or do anything deliberately, nor does it always tend towards the best way to do something or a beneficial mutation. The author also engaged in this flaw by giving fetuses wills (similar to how some writers anthropomorphize animals including primates). So while the doctor goes on in the whole post comparing different species and their different gestational evolution, at the end of the day, it's just a theory that combines different points. Edit: Downboats? Berry?! Not on my HN!
- gugagore 9y ago> The quotes are to indicate that this isn't about what they consciously want, but about what evolution tends to optimize. Sounds like the author tries to address your point.
- mbroshi 9y agoApparently some mice do menstruate[1]. Do mice have another mechanism for handling the issue the author raises: "What to do when the embryo died or was stuck half-alive in the uterus?" [1]: https://www.nature.com/news/first-rodent-found-with-a-human-like-menstrual-cycle-1.20072 https://www.nature.com/news/first-rodent-found-with-a-human-...
- jessaustin 9y ago
- lazysheepherd 9y agoSame story illustrated by TED-Ed, which I would suggest you to watch: https://youtu.be/cjbgZwgdY7Q https://youtu.be/cjbgZwgdY7Q I happen to watch it few weeks ago and this reminded me of it.
- letientai299 9y agoAfter reading this, I just miss my mother so much. Can't imagine what I've done since I'm still a fetus.
- gugagore 9y agoIf I read anything about human reproduction, I remember "The Egg and the Sperm: How science has constructed a romance based on stereotypical male-female roles" by Emily Martin. https://web.stanford.edu/~eckert/PDF/Martin1991.pdf https://web.stanford.edu/~eckert/PDF/Martin1991.pdf one quote in relationship to the comparison between ovulation and spermatogenesis: "By extolling the female cycle as a productive enterprise, menstruation must necessarily be viewed as a failure."
- cryptonector 9y agoShorter version: menstruation probably only exists to potentially flush failed pregnancies.
- teacpde 9y ago> Normal mammalian pregnancy is a well-ordered affair because the mother is a despot. Her offspring live or die at her will; she controls their nutrient supply, and she can expel or reabsorb them any time. Human pregnancy, on the other hand, is run by committee – and not just any committee, but one whose members often have very different, competing interests and share only partial information. Such eye-opening and fascinating analogy.
- grzm 9y agoThanks for the quote. That said, please don't use indentation to set off block quotes, as it makes it very difficult to read, especially on mobile devices. Common methods of block quoting on HN is prefixing with ">" and possibly using asterisks to italicize the text, and possibly wrapping it in quotation marks.
- teacpde 9y agoThanks for the tip, I checked it up on mobile, it's indeed hard to read. Should be better now.
- diedyesterday 9y agoTL;DR => Menstruation in human females is a monthly self-cleansing (although wasteful) FLUSH to get rid of all those "unworthy" scum who didn't make it as viable fetuses. Because being considered "worthy" by mother grants you (the fetus) root-level, administrator access to her body (Yes, we human fetuses are that aggressive and we don't know why!). So be warned that there is a tough screening process going on before you get accepted and gain root-level permanent access!!! Otherwise you will end up in nasty menstrual blood!