The Outline of History: Being a Plain History of Life and Mankind

e, that was creeping in the shallow waters and intertidal muds of the early Pal?ozoic p

rtain power of growth, all living things take nourishment, all living things move about as they feed and grow, though the movement may be no more than the spread of roots through the soil, or of branches in the air. More

into the likeness of their parent. Among more complex creatures the reproduction is not usually such simple division, though division does occur even in the case of many creatures big enough to be visible to the unassisted eye. But the rule with almost all larger beings is that the individual grows up to a certain limit of size. Then, before it becomes unwieldy, its growth declines and stops. As it reaches its full size it matures, it begins to produce young, which are either born alive or hatched from eggs. But all of its body does not produce young. Only a special part d

lity. A thousand butterflies this year may produce two or three thousand next year; these latter will look to us almost exactly like their predecessors, but each one will have just that slight difference. It is hard for us to see individuality in butterflies because we do not observe them very closely, but it is easy for us to see it in men. All the men and women in the world now are descended from the men an

ntinually dying and being born again

icular single cases any sort of luck or accident may occur, but on the whole the better equipped individuals will live and grow up and reproduce themselves and the weaker will as a rule go under. The latter will be less able to get food, to fight their enemies a

hat every species, so long as the conditions under which it lives remain the same

on at all under the old conditions may now find its opportunity. These species will change, therefore, generation by generation; the old sort of individual th

als as have the thickest, whitest fur will be least hurt by the cold, less seen by their enemies, and less conspicuous as they seek their prey

e in the Later

fly is shown. There were amphibia like gigantic newts and

g and a thinner fur will find itself at an advantage, and very white and heavy fur will be a handicap. There will be a weeding out of the white in favour of the brown in each generation. If this change of climate come about too quickly, it may of course

it will be modifying towards brownness and a thinner coat. At the same time there will probably be other changes going on; a difference in the paws perhaps, because one half of the species will be frequently scratching through snow for its food, while the other will be scampering over brown earth. Probably also the difference of climate will mean differences in the sort of food available, and that may produce differences in the teeth and the digestive organs. And there may be changes i

tion and differentiation must occur, old species must disappear, and new ones appear. We have chosen for our instance here a familiar sort of animal, but what is true of furry beasts in snow and ice is true o

sandy and muddy shores of the rocky lands and the air was full of clouds and steam, must have been modified and varied and species must have developed at a great

ry great variety of widely contrasted forms before it began to leave traces in the rocks. The Record of the Rocks does not begin, therefore, with any group of closely related forms from which all subsequent and existing creatures are descended. It begins in the midst of the game, with nearly every main division of the animal kingdom already represented.[9] Plants are already plants, and animals animals. The curtain rises on a drama in the sea that has already begun, and has been going on for some time. The brachiopods are discovered already in their shells, acc

ith life, the land above the high-tide line was still, so fa