The book tells very pessimistic story of the future in which earth falls apart due to environmental destruction.

It gets more implausible as it goes on, but then again the plausibility of various forms of future 'homo' evolution is pretty much an epistemic black hole. This is the least scientifically plausible Dougal Dixon book I've read, but I still enjoyed its wonderful weirdness.

That's basically, what most of the future human species in Man After Man are - very promising speculative ideas overburdened by piling irrelevant, random and overall daft pseudo-scientific crap on top of them, killing any semblance of seriousness. The concept of the parashrew was laughably stupid and that particular creature seemed less like the work of Dixon and more like something out of the fantasies of a five year old. And this isn't the first time he's done the same mistake : Even his true classics, After Man and The New Dinosaurs, are often burdened by needlessly out-there species - for instance, the 'parashrew' of After Man shook my suspension of disbelief, which until then had no problems with the fictional future animals presented. Doug seems to understand evolution pretty well, but I just get the feeling he can't resist the urge to make 'clap your hand if you believe, because this is cool shit' assumptions, that needlessly bring the book's atmosphere into the realm of uneducated pulp sci-fi. Even us, the currently last human species, have had a vaguely unchanged form for 40 000 years (and yet we are still evolving, even though it's visible only in small details over the many millenia and not some kind of Hollywood Turbo Evolution (tm) as in this book) ! Furthemore, while the posthuman stuff in the early chapters of the book is pretty much fully believable, many of the latter species that crop up in the book are borderline cartoonish or act nothing like an extinct or existing natural species would. I mean, come on ! Even if we accept that many of the starting stock species were genetically engineered and have some latent special capabilities 'built in', the time it takes them to evolve into a completely new form is laughably short - just a few hundreds or few thousands of years (like, only 2000 !). The premise and many of the ideas presented are intriguing, but I severely dislike the ridiculously unrealistic timeframe that the evolution of Dixon's future human species is set in. Compared with the other titles by Dixon, this is a major misstep.

Man after man dixon