Time Travel And Future Histories II

In "Time Travel And Future Histories", I made what I thought at the time was a neat comparison between some seminal works by Wells and Anderson:

social classes devolve into distinct species in The Time Machine but are ended by social revolution in The Shape Of Things To Come;

mankind evolves rather than devolves in the Time Patrol series, is artificially mutated in the Psychotechnic History and becomes extinct but is re-created by a post-organic intelligence in Genesis;

mankind migrates to the galactic center in the Psychotechnic History but spreads through several spiral arms in the Technic History.

By passing directly from Wells to Anderson, I omitted two intermediate authors: Stapledon succeeded Wells and Anderson succeeded Heinlein.

Mankind evolves through eighteen species, some capable of mental time travel, in Stapledon's Last And First Men;

telepathically linked organic beings living throughout the universe form a Cosmic Mind in Stapledon's Star Maker whereas electromagnetically linked post-organic beings spreading throughout the universe start to form such a Mind in Anderson's Genesis.

These additional comparisons confirm that Stapledon was a worthy successor of Wells and that Anderson was of both.

Heinlein made major contributions to time travel, future history and future revolutions but, unlike the others, did not project any future evolutionary stages of mankind.