EVOLUTION
CHAPTER I
THE EVIDENCE FOR EVOLUTION
The idea of Evolution is an old one. It is older than the Darwinian hypothesis; it is older than Lamarck, who published his particular theory in 1809, the year that Darwin was born; it is older than Buffon or Kant. In a fairly definite form it is as old as Aristotle. The Evolution idea has thus itself evolved, and is the product of many centuries of thought. Yet it was only the last generation that began to give the idea serious consideration, and it is perhaps only the present that has granted it any general measure of acceptance; and it was Darwin who wrought this change, who raised the conception of Evolution from the status of a vague speculative idea to that of a well-grounded theory, which appeals to the majority of educated minds as satisfactory and reasonable.
We do not here propose to sketch the development of the idea, either before or after Darwin; but only, in the first place, to state the grounds on which the belief in Evolution is based, and, in the second, to trace roughly the lines along which animal Evolution has proceeded. In the first few pages of this book, then, we shall endeavour to bring forward some of the evidence on which the modern Evolution theory rests.
Evolution
| First Appearance of Types. | Dominant Types. | |||||
|---|---|---|---|---|---|---|
| Modern | ... | Man | } | Post-tertiary, 1/2 per cent. | ||
| Diluvium | Man | ... | ||||
| Pliocene | ... | } | Mammals | } | Tertiary or Cænozoic, 2-1/2 per cent. | |
| Miocene | Monkeys | |||||
| Oligocene | ... | |||||
| Eocene | Lemurs | |||||
| Cretaceous | Higher mammals | } | Reptiles | } | Secondary or Mesozoic, 11 per cent. | |
| Jurassic | { | Birds Marsupials | ||||
| Triassic | Monotremes | |||||
| Permian | Reptiles | Amphibians | } | Primary or Palæozoic, 32 per cent. | ||
| Carboniferous | Amphibians | } | Fishes | |||
| Devonian | Lung fishes | |||||
| Silurian | Lower fishes | ... | ||||
| Cambrian | ... | ... | } | Archäen, 54 per cent. | ||
| Laurentian | ... | ... | ||||
Fig. 2.—Table showing the chronological succession of the stratified rocks, the subdivision of geological time, the approximate position of the earliest fossils of each of the main types of vertebrates, and the period of domination of each group.
As our first witness, we may call the rocks which constitute the outer portion of the earth, and ask them to tell us what they remember of the history of life upon the planet. We cannot hope for the whole truth from them, for their memory is imperfect; and yet they can tell us a great number of important facts.