Texhnolyze, Jinrui wa Suitai Shimashita Recommendations
While these two anime couldn't be more dissimilar in terms of art style, tone, and pacing, they do both explore the theme of humanity's decline as a species. Texhnolyze is a dark, slow paced, and extremely moody series that handles the subject matter in a very serious fashion. Jinrui wai Suitai Shimashita, on the other hand, is infinitely more humorous and colorful, though dark undertones are still present throughout. I would recommended both of these series to anyone who is interested in seeing a similar theme handled in two completely different ways.
Jinrui wa Suitai Shimashita is basically Texhnolyze: The Comedy, as fucked up as that sounds (it is fucked up). JSS isn't soul-crushing or graphic, rather it makes light of humanity's tendency to take that extra mile we didn't need, turn it into a spiked dildo, and fuck ourselves with it. Obviously not for everyone, but if you're a miserable ass like me, you'll find Texhnolyze powerful and JSS hilarious.