If it seems plausible that the Mouse Utopia accumulation of deleterious genetic mutations may have had a role in the modern phenomenon of New Leftism or Political Correctness - then how might this work?
The basic idea is that generation upon generation mutation accumulation - beginning in the upper classes - has had several effects. One is to reduce intelligence (specifically 'g' or general intelligence).
But reducing intelligence is not really the root problem, because the insanities of Political Correctness are so gross as not to require high intelligence to comprehend them - indeed, Political Correctness arose and took root and grew mostly among those of above average intelligence.
Neither does the maladaptiveness of Mouse Utopia lead to evil - evil has other sources.
The problem is a failure of common sense, of basic instincts to detect threat and for survival - the failure of normal and adaptive motivations in relation to social life and sexuality.
The way I think it worked is that there were always foolish and wicked ideas in the public arena; but in the past there was a sufficiently high average level of common sense that the foolishness was obvious, and the need to reject foolish ideas on common sense grounds was compelling.
Nowadays many, perhaps most, people lack the most basic understanding of what is normal, pathological, healthy, damaging, adaptive, disgusting, desirable, sensible, stupid. Therefore ridiculous notions are accepted and gone-along-with, with little more than a vaguely confused shrug. Therefore wicked, destructive, horrible ideas are accepted and gone-along-with when they are wrapped-up in the grossest and most clear-cut nonsense.
So, this is what I think may have happened. After several generations of Mouse Utopia, many social and sexual adaptations have been damaged in many different ways in most people - so it is possible for the small minority of purposively evil masterminds behind Politically Correct Leftism to impose their ideas on a modern population, where they inflict personal and social damage of many types - when this imposition would have been impossible in any previous human society.