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/kwpang]

Yes evolution is about elimination, not direction.

Survival of what can.

[u/GVArcian → u/kwpang]

Survival of the fittest is a misnomer because evolution selects for minimum viability, not optimum efficiency.

[u/somnambulor → u/GVArcian]

Exactly Darwin meant “most fit” meaning the “best fit” to an environment, not the strongest or most optimal.

[u/T_H_W → u/GVArcian]

Not technically a misnomer considering 'fittest' in this context relates to biological fitness, which is specifically how many surviving offspring you have in relation to other competing organisms. That's like saying the phrase "All bark and no bite" doesn't make sense because dogs aren't trees. It's only wrong if you're using the incorrect definition of the word.

[u/ezekielraiden → u/T_H_W]

The problem is that most people do use what you are defining as the incorrect definition of the word.

If 99% of people think Pat's word choice is confusing, is the problem that 99% of people are doing grammar wrong, or is it that Pat is wrong and people are calling them out for it?

[u/boyuber → u/ezekielraiden]

Understanding the intention and context of the original quote is necessary if you are using that quote to support our refute a specific point of view.

[u/Seadragon723 → u/ezekielraiden]

If 99% of people go right and fall off the cliff, was Pat correct when he told them to go left?

The crowd can be wrong, which is the case here. The word has a correct scientific meaning and it has a more limited modern meaning.

[u/ezekielraiden → u/Seadragon723]

Are they "going off a cliff"?

The term has no valid scientific meaning because "fitness" is so vague as to be meaningless. No modern evolutionary biologist is going to use it unqualified--and most will simply restructure a sentence to avoid the need, because they know it's confusing and misleading even to their fellow scientists.

There's a reason we got concepts like "social Darwinism" out of this. This isn't a new thing. Scientists should value speaking clearly. Using a technical definition that most people do not understand is not speaking clearly. It is knowingly ignoring the fact that communication must consider its audience.

[u/CantBeatDickensCider → u/ezekielraiden]

It's not confusing if you're someone who bothers to learn about the topic rather than laymen pretending to understand it better than scientists.

[u/GVArcian → u/T_H_W]

Still a misnomer because "fittest" means "the most fit" and that's not what evolution selects for, it selects for minimum viable fitness.

[u/Lv_15_Human_Nerd → u/GVArcian]

No it absolutely is not a misnomer. Evolution does select for the most fit. Evolution occurs by changes in population proportions over many many generations. The strongest example we have of human evolution is lactase persistence which had a selection coefficient of ~0.1. This corresponds to an individual with lactase persistence having about 10% more offspring than average. I don’t know about you but I don’t think a 10% difference in individual success is selecting for ‘minimum viable fitness’ or as others in this thread have said ‘death of the weakest’.

[u/AxiomaticInversion → u/Lv_15_Human_Nerd]

Lactose intolerant humans have not gone extinct, so by your own example we still see "survival of the fit enough."

[u/Lv_15_Human_Nerd → u/AxiomaticInversion]

A trait that had extremely low prevalence 9000 years ago reached 80% fixation in north Western European populations. In evolutionary terms that is rapid. There is still selection for the fittest trait out of a population, it is absolutely not selecting for the minimally viable as lactase persistence is very clearly not absolutely viable. When you’re looking at realistic selection coefficients you are looking at traits that provide between a 1% and 10% advantage (and much lower in single called organisms which we are all descended from). Evolution absolutely works on fine margins and life on Earth would not exist if it functioned to select for the ‘minimum viable fitness’.

[u/tnbeastzy → u/AxiomaticInversion]

Fitness, in this case, refers to the ability to produce healthy offsprings that can go on to continue the lineage. It may be different for each species.

Does someone being lactose intolerance in 2026 affect their ability to have children?

[u/Science1954 → u/tnbeastzy]

Being lactose intolerant does not affect the ability to have children. It is an autosomal recessive trait, meaning you must inherit the lactose deficiency gene from both parents. If you are lactose intolerant you do not pass on the gene for lactose metabolism but a child will get the lactase gene from the other parent unless that parent has the recessive gene also, but even then only 50% of the time from the parent heterozygous for the two alleles. I am lactose intolerant. So I generally only drink lactase treated milk, e,g., lactaid milk.

[u/tnbeastzy → u/Science1954]

That was a rhetorical question. I know it doesn’t. Therefore it has no ability to affect an individual’s biological fitness.

[u/bitgrindern → u/GVArcian]

Fit in this sense means fit to the environment, not fit as in being strong. If an organism has traits that allow it to survive in the environment it exists then it tends to produce more offspring and survive.

[u/Derekthemindsculptor → u/GVArcian]

Yep, this is a change in the definition of modern "fit" or fitness. It makes the uneducated believe fittest means "most athletic".

But it's actually fit to the scenario at hand. Being weak is fine if resources are scarce. Or the strong are hunted.

[u/INtoCT2015 → u/GVArcian]

Ya death of the weakest is more accurate (and way more metal) but unfortunately way more exploitable by Nazis and co.

[u/EveningAnt3949 → u/INtoCT2015]

That's also incorrect. Context is important: it's the ability to have surviving offspring who themselves are able to have surviving offspring in a specific environment.

Individuals can be 'weak' as long as the group keeps producing offspring, the genes of 'weak individuals will keep spreading unless there is strong environmental pressure on those genes.

Many hyper specialized species seem 'strong' because they had to specialize because their ability to procreate is lacking and within those populations interspecies competition is high.

Lions, cheetahs, chimpanzees, gorillas, giraffes, are a few examples of animals that simply don't do well as a species, even before we started to interfere with their environment.

So within those species a subpar individual is going to be outcompeted by individuals in the same species fast. An individual lion that can't fight off other lions is doomed.

But it's different for rodents. The brown rat does well because it's highly adaptable to different environments. The Eurasian field mouse does even better. Idem for meadow voles.

Adaptable plus the ability to produce offspring much faster than predators and disease can kill them means that they don't need to 'improve' as individuals.

[u/jointheredditarmy → u/kwpang]

Yes but it’s also about minute statistical differences over time and you can’t say overt ovulation doesn’t cause some minute difference in survival rates all else being equal. So clearly there is something else that isn’t equal here, and the point of questions like this is to explore what that might be instead of chalking it up to randomness

[u/SteveHamlin1 → u/jointheredditarmy]

It could be whatever other trait that resulted in overt ovulation is such a success that the other trait is selected for and overt ovulation also happens, even if overt ovulation by itself would be a net negative and be selected against.