These are the words penned by one of the most respected population geneticists on the planet:
the genetic system is not optimized to result in increase of fitness by natural selection.
when we involve multiple loci, mean fitness can actually decrease as a net result of natural
selection and recombination, – Joe Felsenstein
And I’ll add, given that 90-99% of the “beneficial” mutations are actually functional compromises (like tape worms losing organs), the meaning of the phrase “fitness increasing” itself becomes dubious.
And that is one of the reasons I find creationism more believable than evolutionism.
As the historian Glick quipped: “Mendelism killed Darwinism”.