Pretty brilliant book laughing at various theories of evolution. Though rather pessimistic in the end, as per the chances of any intelligent species to organize their lives reasonably well. The story is of a post-human Earth which emerged as a result of biotech intervention which made animals intelligent and made some people into intelligent animals. While these consider several attributes of human societies (money, labor division) irrational to the point of insanity, the society they created is too hierarchical not to be very similar to the human ones. While the intelligent animals destroyed the humanity they, in their turn, were attacked by a newly emerging silicon-based intelligent form which made use of human women. The animals had to emigrate and establish colonies on other planets (Mars, Venus). On Mars a society imitative of humanity developed, on Venus there was an ongoing experiment in inducing lizards to constantly fight each other in order to check the hypothesis that aggression is conducive to development of culture. On Earth in the meantime time, at least in theory, became circular. There is also in the last part of the book this story about brother and sister who had some mystical mission and ended up living as a couple on Earth. I found the brother and sister story somewhat less original than the rest of the book.