The Very-Many-Questions-Not-Worth-Their-Own-Thread Thread XL

[MaryKB]

I'd imagine birds in the wild probably find a mate to help them fertilize their eggs.

 

[tjs282]

Did also sort of think you know like I haven't seen other birds laying unfertilised eggs like that, but maybe they do

Wild birds (and most wild animals) only lay eggs/ reproduce when they've managed to acquire sufficient excess energy reserves (food) to 'allow' them to invest it in offspring.

Not enough food = No eggs/babies. Domestic chickens don't usually have to contend with that problem.

I have read that human females with insufficient calorie-intake also eventually tend to stop ovulating. Again, not usually a problem for First-worlders (unless someone's on a starvation diet, or engaging in constant strenuous physical training), but likely more frequent in famine-struck areas.

 

[The_J]

Probably for the same reason that female humans end up bleeding all over the damn place over month.

Well, that's considered to be kinda an evolutionary error, so shouldn't be representative.

 

[aimeeandbeatles]

Well, that's considered to be kinda an evolutionary error, so shouldn't be representative.

I thought the reason for it was because building and shedding the lining every month cost less in energy than to just maintain it constantly.

 

[MaryKB]

Well, that's considered to be kinda an evolutionary error, so shouldn't be representative.

Um, no.

Men of CFC: Please, for the love of all that is good, I'm begging you to please not weigh in your "opinions" on menstruation.

 

[MaryKB]

I thought the reason for it was because building and shedding the lining every month cost less in energy than to just maintain it constantly.

Basically, yes. We need a thick layer to prevent our babies from eating us alive, and we'd need more energy to keep that up 365 days a year than to shed at replace it 13 times.

 

[aimeeandbeatles]

I found this: http://www.bbc.com/earth/story/20150420-why-do-women-have-periods

 

[Farm Boy]

One thing that made me wonder is that I read somewhere that birds extract calcium from their own bones to make eggshells, which I kinda figured would be something to hold in controll, but it might be you know like,, the amount of eggs they produce in a lifetime sort of synchs up with how long that lifetime is

Just to add a little more, the calcium is a problem for domesticated chickens, which have been selectively bred to be consistent layers. Those chickens will generally have good enough caloric intake to lay an egg, but if their diet is short on calcium, they'll lay leathery eggs. They'll cannibalize any broken eggs for the fats and again, calcium, in a frenzy. If they don't get good vitamins when they're growing, they're susceptible to a variety of bone malformations, sometimes you'll get one with a droopy neck they can't lift up if they didn't get good nutritional supplements, just calories. So yar, it's a complication that's compounded with domestic nature. They're still way happier, generally, with a rooster around.

 

[Lexicus]

I thought the reason for it was because building and shedding the lining every month cost less in energy than to just maintain it constantly.

That's fascinating, I didn't actually know that.

 

[The_J]

Um, no.

Men of CFC: Please, for the love of all that is good, I'm begging you to please not weigh in your "opinions" on menstruation.

I wanted to refer to this study https://www.pbs.org/wgbh/nova/article/evolution-female-orgasm-ovulation-rabbits/ from last year, which basically says that the normal mode was climax-triggered ovulation, and that in some species this has decoupled for whatever unknown reason (and as it is in evolution, these things start out as an error normally).

 

[MaryKB]

I wanted to refer to this study https://www.pbs.org/wgbh/nova/article/evolution-female-orgasm-ovulation-rabbits/ from last year, which basically says that the normal mode was climax-triggered ovulation, and that in some species this has decoupled for whatever unknown reason (and as it is in evolution, these things start out as an error normally).

Please stop.

1. I'm not a rabbit.
2. The last line in this article clearly says "There's nothing wrong with women."

As Aimee and I said above, menstruation is due to a thicker uterine lining needed by primates to protect the mother from the baby, and maintaining that lining permanently requires much more energy than shedding and replacing it.

 

[The_J]

I didn't intend to say that anything is wrong with women.
What I wanted to say is what the article says: Having a monthly menstruation (or regulary egg laying, or whatever) was not how this probably originally once worked. (and there's still nothing wrong with that; I'm doing lots of things which were not supposed to work as they are).
Same probably applies to the egg laying hens, to get back to the original point.
So both are not representative of the majority of all organisms (probably), so using either to infer a reasoning for the other is probably not helpful.

 

[aimeeandbeatles]

According to the BBC article, there's a few other mammals that menstruate:

It seems the list of animals that menstruate is quite short: humans, apes, monkeys, bats and elephant shrews. What do these seemingly disparate animals have in common?

It all comes down to how much control the mother animal has over her own womb, according to Deena Emera of Yale University in New Haven, Connecticut. In a paper published in 2011, Emera and her colleagues pointed out that in menstruating animals, the transformation of the womb wall is entirely controlled by the mother, using the hormone progesterone.

Embryos can only implant in the womb wall if it is thick and has specialised large cells, so this means the female is effectively controlling whether or not she can get pregnant. This ability is called "spontaneous decidualisation".

In most other mammals, these changes to the womb are triggered by signals from the embryo. In effect, the womb lining thickens in response to pregnancy.

"There's a nice correlation between species that menstruate and species that exhibit spontaneous decidualisation," says Emera.

 

[The_J]

I wonder if someone has phylogenetically looked at this. It might be possible to do something in this area via comparative genomics, to see which genes are responsible .

 

[MaryKB]

I didn't intend to say that anything is wrong with women.
What I wanted to say is what the article says: Having a monthly menstruation (or regulary egg laying, or whatever) was not how this probably originally once worked. (and there's still nothing wrong with that; I'm doing lots of things which were not supposed to work as they are).
Same probably applies to the egg laying hens, to get back to the original point.
So both are not representative of the majority of all organisms (probably), so using either to infer a reasoning for the other is probably not helpful.

You referred to human women as "an evolutionary error."

 

[The_J]

I meant the development of the menstruation.

 

[aimeeandbeatles]

I wonder if someone has phylogenetically looked at this. It might be possible to do something in this area via comparative genomics, to see which genes are responsible .

I'm a bit curious too. I'm not surprised at the apes/monkeys that can menstruate, but bats and elephant shrews are interesting.

 

[The_J]

Yes, this is a pretty bizarre combination.
Also an interesting example of convergent evolution .

EDIT: I might guess though that the species diversity is undersampled though.

 

[MaryKB]

Again, it's not an error. It's necessary.

 

[The_J]

Oh, no arguing with that.
But there are other modes which could have made the same possible, of which one is apparently more ancestral than the current mode.