But the answer which geology gives to our questions as to the probable confirmation of the evolution theory, naturally becomes most interesting where the _origin of man_ is treated of. Our attention is, therefore, especially directed to the most recent formations of the globe which show us the oldest remains of man. The most instructive are those parts of the skeleton which allow us to draw the most convincing conclusions as to the degree of mental development of an individual, namely: the parts of the skull. Although human bones seem to have been less easily preserved than those of animals, and are, comparatively speaking, very scarce, especially more so than prehistoric implements, still there are not wanting such remains, which go back far beyond historical time. The oldest known skull is the celebrated one of the Neander cave near Duesseldorf, with its large vault of the forehead, and its low height. Although Virchow finds on it evidences of rachitis in youth and of gout in old age, as well as of injuries, it nevertheless can not have been changed in its _fundamental form_ by any sickness, even according to Virchow. This very skull now indisputably shows a still lower formation, which, although quite essentially different from the type of the ape, stands nearer to it than is the case with the skulls of men in later times. Of a later date, and of a correspondingly higher form, are the skull of Engis, of Cannstatt, the skulls of the Belgian caves (especially Chauvaux), of France, and of Gibraltar. According to the weighty authority of Schaaffhausen (note his opening address at the Wiesbaden Congress of the {86} Anthropological Society, 1873), the skulls and the remaining parts of the skeleton show more indications of a lower formation the older they are. He especially calls attention to a certain bone of the roof of the skull--the _Os interparietale_ or the so-called _Os Incae_--which has only recently been recognized as a characteristic of a lower formation of skulls, standing nearer to that of animals. As late as the summer of 1873, two human skeletons were found at Coblenz in a volcanic sand, of which Schaaffhausen says: "No less than eight anatomic marks of a lower formation, which probably have not heretofore been found together, indicate the great age of these remains." With all these traces of a difference between the former and the present state of the physical condition of man, the differences between the type of man and that of the animal are still great enough to leave wide open the possibility of the origin of man through some other means than that of gradual development. On the other hand, it is more or less in favor of the evolution idea, that so far such old remains of man have been found in places which certainly can not have been the cradle of mankind, and that those parts of the earth which we would naturally suppose to be the first dwelling place of the earliest human genera have been little or not at all investigated.