The fall of the nineteenth century abounded in discoveries of natural laws, that is, strict and unequivocal rules of the development of life. These laws stated for example that ontogeny of individuals repeats, or recapitulates, phylogeny of the species; that big and specialized forms originate in evolution from small and unspecialized ones, while the reverse is not true; that endothermic animals are larger-sized and more compact in cool than in warm climates, and so on. Louis Dollo, a Belgian palaeontologist, proposed (...) the so-called law of irreversibility of evolution which stated that an organic structure lost in evolution cannot reappear with all the peculiarities of its design. This law seems indeed to be true but not particularly original. It was Heraclitus who first observed that one could not enter the same river twice. Dollo's law says essentially the same thing. The flow of evolutionary events combines so many processes in so many ways that past evolutionary events cannot recur exactly. “What is done, is done forever”. Time itself introduces asymmetry into the evolutionary process. (shrink)

The first principle of evolution is immutability; the primary objective of a species is to perpetuate itself. A transition from one species to another has never been observed and never will be; even in paleontology the study of fossils will never bring to light a continuity in the history of life: the passage from one form to another is always abrupt, and the “missing links” are only a creation of our imagination, an answer to satisfy our expectation.

If a meteorite had not fallen on the earth sixty-five million years ago, we would not be where we are now; or more exactly we would not be here at all. If icebergs had not covered a third of the globe's surface three hundred million years ago, this collision some two hundred and thirty-five million years later would have been of no benefit to us. If drought had not swept over the Eurasian continent some ten million years ago, we would (...) still be in the trees, and nothing would encourage us to come down from them. (shrink)