On a cellular level for most all animal life, &quot;nature&quot;&#x2F;evolution doesn&#x27;t care about a long healthy <i>post-reproductive</i> lifespan (there was never and couldn&#x27;t be reproductive selection pressure for that) --- since most everyone can handle western diet approximately up to their reproductive&#x2F;prime age without adverse effects on their reproductive capacity, I see no &quot;derailing of evolution&quot;. Heck, evolution is a never-ending series of derailings by definition.<p>Sure, they breed kids with a gut flora that deals with indigestable cellulose even worse than previous generations, but will they make it to their own reproductive prime age? Chances are, they will.<p>Which is all &quot;evolution&quot; cares about, harsh as it may sound.