Can you explain to me the difference between 'survival of the fittest' and 'survival of the most flexible'?

@Mcflewster Survival of the fittest is perhaps an unfortunate wording by 19th-century scientists. It really refers to the most fit to survive and propagate in a given environment. In that sense it actually does mean that those who are the best able to adapt to their environment, and very importantly, to changes in their environment are the most likely to survive and pass on their genes to future generations. Some people prefer to use the word "flexible" rather than "adaptable". However, I find the phrase "flexible" to the environment more awkward than "adaptable" to the environment. Also, I prefer to reserve the term "flexibility" to what I consider a more appropriate use of the word such a Cognitive Flexibility which is an aid to the survival of the fittest or the most adaptable, but not the same thing.

@Heraclitus Perhaps both words are needed because if conditions around you change then you have to be flexible to make the most of what is available , but you have not actually adapted yet. Then comes adaptable over a longer period?

@Mcflewster No real disagreement there. That is a good way to look at it.

@Mcflewster "Fittest" is a general term...it can mean which organism is most "flexible" or "adaptable"...but certain genes have different "frequencies" of appearance...so a relatively
inflexible/rigid/narrow-scoped-niche organism can turn out to be the "fittest" for survival.

As Homo sapiens has.

For example; Raccoons are doing so well because they're very "adaptable" to both diet and habitat...so they're good survivors because they're "flexible".

Humans evolved a very narrow niche, however. We're essentially "naked" so we evolved a need for clothing. We're stuck with requiring 12 or more years of education to compete for survival because we're overcrowding our habitat...so the strongly educated will survive better. We've become so dependent on technology, farming, hospital-health care and media, that few - if any - of us can survive without in raw climate situations.

Consider the Cetaceans. Very flexible and adaptable. No technology. No money. No hospitals. Advanced communication. No farming. No clothes. The children play all day. The adults make love all day.

No "formal" education required....and if it weren't for us competing with them for food, they'd probably be the dominant being on the planet.

If there's a massive climate disaster, and most - if not all - land plants and animals perish....evolution will rewind 50-100 million years...and its likely Cetacean lifestyle will occur among the animals that start over - and crawl up on the land-scoured landscape of the future.

So the next dominant land species might live just like Dolphins do today....on land.

Have never thought about this concept.