Of course, if one puts the skeleton of a man and the skeleton of a gorilla side by side, their general resemblance is so great that it is easy to jump to the conclusion that the former is derived from such a type as the latter by a process of brain growth and general refinement. But if one examines closely into one or two differences, the gap widens. Particular stress has recently been laid upon the tread of the foot. Man walks on his toe and his heel; his great toe is his chief lever in walking, as the reader may see for himself if he examines his own footprints on the bathroom floor and notes where the pressure falls as the footprints become fainter. His great toe is the king of his toes.
Among all the apes and monkeys, the only group that have their great toes developed on anything like the same fashion as man are some of the lemurs. The baboon walks on a flat foot and all his toes, using his middle toe as his chief throw off, much as the bear does. And the three great apes all walk on the outer side of the foot in a very different manner from the walking of man.
The great apes are forest dwellers; their walking even now is incidental; they are at their happiest among trees. They have very distinctive methods of climbing; they swing by the arms much more than the monkeys do, and do not, like the latter, take off with a spring from the feet. They have a specially developed climbing style of their own. But man walks so well and runs so swiftly as to suggest a very long ancestry upon the ground. Also, he does not climb well now; he climbs with caution and hesitation. His ancestors may have been running creatures for long ages. Moreover, it is to be noted that he does not swim naturally; he has to learn to swim, and that seems to point to a long-standing separation from rivers and lakes and the sea. Almost certainly that ancestor was a smaller and slighter creature than its human descendants. Conceivably the human ancestor at the opening of the Cainozoic period was a running ape, living chiefly on the ground, hiding among rocks rather than trees. It could still climb trees well and hold things between its great toe and its second toe (as the Japanese can to this day), but it was already coming down to the ground again from a still remoter, a Mesozoic arboreal ancestry. It is quite understandable that such a creature would very rarely die in water in such circumstances as to leave bones to become fossilized.
It must always be borne in mind that among its many other imperfections the Geological Record necessarily contains abundant traces only of water or marsh creatures or of creatures easily and frequently drowned. The same reasons that make any traces of the ancestors of the mammals rare and relatively unprocurable in the Mesozoic rocks, probably make the traces of possible human ancestors rare and relatively unprocurable in the Cainozoic rocks. Such knowledge as we have of the earliest men, for example, is almost entirely got from a few caves, into which they went and in which they left their traces. Until the hard Pleistocene times they lived and died in the open, and their bodies were consumed or decayed altogether.
But it is well to bear in mind also that the Record of the Rocks has still to be thoroughly examined. It has been studied only for a few generations, and by only a few men in each generation. Most men have been too busy making war, making profits out of their neighbours, toiling at work that machinery could do for them in a tenth of the time, or simply playing about, to give any attention to these more interesting things. There may be, there probably are, thousands of deposits still untouched containing countless fragments and vestiges of man and his progenitors. In Asia particularly, in India or the East Indies, there may be hidden the most illuminating clues. What we know to-day of early men is the merest scrap of what will presently be known.