Included in that original scenario or hypothesis he advanced was the premise that the "reason why" biological life evolved was to get more fit, get better, become the most fit to survive, thus survival was thereby guaranteed in any particular ecosystem.
Apologists and revisionist historians, who attempt to clean up this problem, ignore the truck loads of books and scientific papers written about it, and retroactively try to clean it up by saying that is not what Darwin meant.
They typically go on to say he meant fit enough to survive in a "local" ecosystem.
But Darwin was not so embarrassed, and flatly said:
"The expression often used by Mr. Herbert Spencer of the Survival of the Fittest is more accurate, and is sometimes equally convenient"(Wikipedia, emphasis added). Social Darwinism was a reaction to Darwin's early writings which ended up being a form of militant imperialism where "survival of the fittest" was interpreted to mean "domination by might".
Survival of the fittest was eventually rejected in that sense, but in Ecocosmology it is plainly pointed out that this cosmos does in fact impose an evolutionary test on all species who inhabit planets near central stars.
Only the fittest will survive, and the fittest are those who pass "The Test".
The nature of "fittest" in that context, set out clearly in The Four Tenets, includes technological evolution as well as behavioral evolution, leaving out biological fitness as the main criterion in cosmological evolution.
Ecocosmology calls for the survival of kinder, gentler, and wiser species, not war like imperialists set on domination.
Biological evolution on a planet circling a central star only sets the stage for the far greater cosmological evolution that must take place in order for species to survive within this cosmos.
In that sense, Darwin was, and his progeny are, majoring in the minors.
There is a need to evolve our thinking, to shift the focus onto what the human species must evolve into in order to sustain human existence across the broader cosmos.
Because it is certain that only those species who have become fit via memetic evolution into a wiser and more competent species will survive.