One statement can be made with as great certainty as any other in this book: short of some cosmic catastrophe, such as the sun becoming a nova, microbes on this planet have a future. This is more than can be said for many animals. It is highly probable, for example, that the days of the mountain gorilla and bonobo chimpanzee are numbered. Though attempts are regularly made to control hunting and poaching, it is unlikely that they will succeed while war and civil strife cause whole populations to hunger for ‘jungle meat’. Likewise the rhinoceros, the pangolin, the osprey and at least a hundred and fifty other large mammals and birds are destined to disappear from this planet unless they are successfully preserved in zoos or game reserves; only whales have attracted sufficient international attention for their anthropogenic decline to have been halted – if only briefly. Immensely greater numbers of lesser-known species of animals and plants are likely to vanish, unnoticed except by biologists, as mankind colonizes and modifies the more remote habitats of this planet; the environmentalist Paul R. Ehrlich has asserted that one in ten of the known plant species is threatened. But it was always so: throughout biological evolution, natural selection has involved an unceasing succession of extinctions and emergences of species; mankind has merely distorted the process, in recent centuries rather drastically. Is the startling variety of dogs, brassicas and the like, which our unnatural selection has generated, a sort of compensation, I wonder? Forgive the side-issue.