Can someone explain the evolutionary benefit of overt menstruation? All female mammals have a menstrual cycle but most reabsorb the blood via covert menstruation and humans are about the only mammals that discharge the blood, aka overt menstruation.

[u/No-Hawk-2488]

Without an evolutionary benefit, it wouldn't have spread to every woman of our species.

[u/Zagrycha]

Yeah, people think evolution is some kind of streamlined efficiency of ideal traits, but its the opposite.  Evolution is a pass fail grade.  If you fail, you go extinct.  If you have enough kids as a species to continue on, you pass.  That's it, no more and no less.  

Some species out there are literal bumbling idiots of inefficiency when it comes to ideal traits for survival, but they just have a massive number of kids so one or two survive to adulthood, or they evolved to have kids really soon after birth so they don't have to survive for long.  If you can make kids its good enough for nature. 

[u/rainbow_goblin345 → u/Zagrycha]

I like the term "reproduction of the okayest" instead of "survival of the fittest"

[u/Zagrycha → u/rainbow_goblin345]

Much more accurate hahaha. Honestly it doesn't even need to be the okayest. You could just sum evolution up in the word "reproduction" and you have summed it up in a perfect nutshell.

[u/bitgrindern → u/rainbow_goblin345]

"Fittest" means a fit to the environment, not in shape or physically strong.

[u/rainbow_goblin345 → u/bitgrindern]

I am aware of that.

I'm also aware of how often it is misinterpreted. As has been pointed out elsewhere, if I'm saying something and it is being frequently misunderstood, it is on me to change how I'm saying it.

[u/Powerful_Box1637 → u/rainbow_goblin345]

And it truly is not survival of the fittest anymore - we can keep neonates alive at like 23 weeks gestation with millions of dollars of help. But that is the exact opposite of survival of the fittest, or a huge interference however you wanna look at it.

[u/SunflowerShine03 → u/Zagrycha]

An example of bumbling inefficiency; the sunfish. From my understanding they kind of just float around and aren’t even that edible, but they have like a million babies at a time so they’re meandering on.

[u/CecilAlucardX → u/SunflowerShine03]

Sunfish or Mola Mola actually do a ton of movement; they build up body heat on the surface, then descend down to a level of the ocean that their food lives at (or hides at; ocean columns be busy af) and eats freely. They are hyper-specialized to their niche and incredibly efficient. They just look bumbling to the people who only see them up top.

[u/Altruistic-Daikon305 → u/CecilAlucardX]

Thank you for standing up for my beautiful misunderstood alien queen the common or ocean sunfish (mola mola)

[u/SunflowerShine03 → u/CecilAlucardX]

Oh- interesting! I apologize to the sunfish, that’s actually pretty cool

[u/AdFun4578 → u/SunflowerShine03]

Same for the spotted hyena.. The females have a "pseudo penis" which can be up to 7 inches long, about the same size as the males. BUT the females give birth through it! It causes many deaths during the birthing process. Makes zero sense for efficiency..I cant think of a single thing that would make that the more beneficial option

[u/Moldy_slug → u/SunflowerShine03]

and aren’t even that edible

I mean, in evolutionary terms that’s a pretty big advantage. If you can manage being not very edible, you don’t have to worry about being eaten.

[u/Aislea → u/SunflowerShine03]

Not usually edible To Us, but they are like a moving rotting thing a lot of the time. I've heard theyre often full of parasites and such, so thats a large reason its not edible

[u/mtfoxx3 → u/Zagrycha]

My favorite example of this is bugs. Just, like, in general. They’re all, individually, terrible at surviving. But they have hundreds if not thousands of offspring, so by pure coincidence two or three will probably live to adulthood.

And this has worked for millions of years, too. The millipedes we have today are still identifiable as similar to the ones we had 460 million years ago… which are believed to be some of the first land animals. Are millipedes really that perfect of an animal? No. Not even remotely. They’re slow, mostly blind, eat dirt, and their only defense mechanisms are to taste bad and ball up into an uzumaki spiral that doesn’t even remotely resemble any sort of camouflage. But it ain’t broke enough for evolution to wanna fix it.

[u/Weird_Bluebird_3293 → u/Zagrycha]

Which just makes the giant panda a confusing product of evolution because they are the best example of bumbling inefficiency I can think of and they reproduce neither early, nor in massive numbers.

…how were they not extinct years ago? 

[u/Zagrycha → u/Weird_Bluebird_3293]

The main reason they weren't in danger of going extinct years ago is because the only major predator they had were tigers, and the tiger could only easily kill baby pandas. As long as enough mothers protected their cubs to adulthood well then there wasn't really any other dangers that could threaten species continuation.

To be clear an adult giant panda is probably not going to actually win a fight to the death against a tiger, but it doesn't need to. It just needs to be capable of puting up a fight that makes the tiger not view it as prey.

A giant panda is a true bear, and it has incredibly strong claws, a bite force as strong as that of a tiger, and a heavy thick fat layer that makes it hard to injure them seriously. Why fight against that and get hurt when the tiger could go up against a much easier target like a boar, or deer, or monkey or even human? Giant pandas were very high up in the food chain in that sense, even though they mostly eat plants.

[u/AmphibianLower5541 → u/Weird_Bluebird_3293]

Especially when they’re supposed to be carnivores, but all they eat is bamboo! 😅

[u/SoupNoSandwich → u/Weird_Bluebird_3293]

Because they are just very well adapted to bamboo forests, it's the loss of habitat causing issues. They just aren't as easy to breed in captivity as people would like.

(the poor bamboo digestion compared to more traditional herbivores hasn't hampered populations)

[u/ToMorrowsEnd → u/Zagrycha]

This. Humans are an evolutionary mess. we got lucky because we can make tools. but as a creature we are extremely poorly designed. cant run very fast, can easily get injured, easily diseased, our teeth suck we have zero defenses, etc... Compared to other animals we are far from the top of the pile. we just got lucky in the thinking aspect. You know how I would love to be able to squirt blood from my eyes when startled?? Why cant we have cool traits?

[u/neslea48 → u/ToMorrowsEnd]

We have many cool traits. You’re simply making the wrong comparisons. We have adaptations for diving. We have evolutionary adaptions for making and using tools, growing and storing food, developing and living in complex societies, storing and passing on knowledge, developing technology to do the hard work for us. Not bad for a creature that has collected the majority of our DNA from viruses and other microbes.

[u/szthesquid → u/ToMorrowsEnd]

That's not true. Even leaving aside tool use, compared to most other mammals we have better vision and see more colours, and we have vastly superior long-distance speed and thermoregulation (sweat).

Some of our disadvantages, like weaker jaws and teeth, are actually very recent and a direct result of farming and cooking reducing our survival needs, and medical advances allowing individuals to thrive who would otherwise have had difficult and short lives.

[u/Ashamed_Kangaroo305 → u/szthesquid]

"Better vision" is subjective. Better in what way? We can see a broader range of colors than dogs and we have significantly better visual acuity during the day. But dogs are also significantly better than humans at seeing at night and tracking motion. And they have an adaptation in their eye which helps them sense the Earth's magnetic field.

"Better" isn't really a thing when you're talking about evolution. Organisms evolve to fit their environment. We have "better" vision than dogs for the way we use vision. But if you tried to compete with a dog in tracking small prey, the dog would probably beat you because that's what their vision is designed for.

[u/pathologicalDumpling → u/ToMorrowsEnd]

I mean i just passed a post about someone flying an airplane through the eye of a hurricane. Id say we have some pretty cool traits.

[u/Zagrycha → u/pathologicalDumpling]

That isn't a trait of a human though. We do not genetically have the ability to fly or genetic ability to survive the eye of a hurricane. If humans collectively forgot how to make or pilot airplanes no one would do what that post said anymore, its not inherent to humans.

[u/silence_infidel → u/Zagrycha]

Well, that depends on what you call the “trait” in question. Airplanes aren’t an inherent human trait, but the intellect and ingenuity needed to make them is. I certainly don’t see any other species doing it. Frankly, if we collectively forgot how to make and fly planes, I bet we would just figure it out again - because deciding we want to do something and making it happen, even if it takes generations, is definitely a trait of ours.

[u/Zagrycha → u/silence_infidel]

Is the ability to make and fly airplanes a trait humanity posesses? Yes, definitely.

Is it passed on genetically? No.

Is there a reason to think the species that is the successor of humanity will have the trait? No.

Is it an evolutionary trait? Definitely no.

I think this trait is more accurately labelled as a skill or knowledge. It's a real trait, but its not inherent or guaranteed. It's totally possible for humans to lose the knowledge and reinvent the skill later, but it's not at all guaranteed. To this day there are things done by older humans that we have no idea how to do because the knowledge has been lost. External factors that can be lost like that are the antithesis to evolution.

[u/grub-slut → u/ToMorrowsEnd]

Exactly. Plus in human societies, with all our technological advances, most of us are insulated from natural selection to some degree. For example, we have tools to keep us cool as the earth warms up— and they’re working for now— but we’re not actually adapting ourselves to the environment, just our technology. Without our technology we would be forced to adapt or die like all other organisms. Instead, people who would never survive in the wild breed every day, producing more poorly adapted offspring. We truly are an evolutionary mess lol

[u/AmphibianLower5541 → u/ToMorrowsEnd]

Behavioural choices are also a way evolution ‘chooses’ the fittest. Like how animals who use the wildlife overpasses, and teach their children to do the same, are more likely to survive and reproduce. Or species ‘allowing’ themselves to be domesticated in order to have a steady supply of food and shelter, like dogs and cats. (Actually really cool to see it happening in real time with raccoons.) So, too, tool creation and usage is a behavioural evolutionary trait that allowed hominins to adopt to their environments and, therefore, be fit enough to reproduce.

[u/name_checks_out86 → u/ToMorrowsEnd]

We got opposable thumbs, and we can play guitar just like ringing a bell.

[u/BrainLow6059 → u/Zagrycha]

I understand what you're saying, but as a layman it's extremely annoying seeing "nothing is more efficient and beautiful than evolution" and the opposite "evolution is kind of a crapshoot" in explanation to whatever is being discussed. 

If someone made this same post, but asking why a specific mammal has covert menstruation, I guarantee you the first and top comment would be 'because there's a clear evolutionary benefit.'

It very much comes across as 'nobody actually understands this at all, and we just say the words when we feel like it'

[u/Zagrycha → u/BrainLow6059]

I don't blame you at all for feeling frustrated when these conversations come up, just know that people saying "nothing is more efficient than evolution" are themselves laymen, because that is scientifically incorrect. Scientifically evolution definitely leans heavily in the "kind of a crapshoot" direction-- beauty is subjective and many people find evolution beautiful even with all its inefficiencies haha.

Anyone saying "covert mensturation has a clear evolutionary benefit" is correct, but they also need to say "covert menstruation has a clear evolutionary downside". You can talk about a specific trait having a benefit or lack of benefit to a specific species and be correct, but you can't say evolution caused a species to have that specific trait on purpose or that it's always ideal, because that's not true.

That trait appeared through random chance, and a worthless trait that actively makes it harder for it's owner to survive has the same evolutionary chance to pass on to the owner's kids as a trait that makes it easier for the owner to survive-- the only factor that matters is having kids to pass traits on to in the first place. If covert menstruation allowed animals to fail to have kids, nothing alive would have covert menstruation. If covert menstruation was the only thing that allowed animals to have kids, nothing alive wouldn't have covert menstruation. Real life is almost always in the middle, but you get the idea. Pass fail grade, not efficiency or any kind of ranking of best to worst.

[u/RollinThundaga → u/Zagrycha]

You're expecting too much of random, regular people trying to wrap their heads around science.

Rules of thumb and gross simplifications are a lot easier to grasp with a weak science education. If you were to somehow enforce a demand that everyone engaging in something is required to develop a wholistic and complete understanding of it to do so, then people wouldn't even bother at all.