Now one of the means that scientists use to determine the races of men is a comparison of skulls, measured in a systematic manner. The objection has been made that no reliance can be placed on these results, because at the present day skulls of all sorts of shapes and sizes can be obtained among people of the same nationality. But these objections would not apply to people of prehistoric times. Their surroundings would be simple and natural—not artificial and complex, as in modern times. In our times people of different nationality are constantly coming in contact, and intermarriage results; but in prehistoric times this was not liable to occur, and so the comparative purity of blood would certainly produce a much greater uniformity of physical features.37 From a very careful examination of a great number of burial mounds in Great Britain, it has been ascertained that in all of those that date back to Neolithic times, and contain portions of human skeletons, the bones are always those of individuals small in stature, the average height being about five and a half feet. The skulls are of that variety known as long skulls. From this we can at once form a mental picture of the Neolithic inhabitants of Britain. No less important conclusions have been deduced from the study of burial mounds on the continent. We meet with remains of these same small-sized people. “They have left traces of their presence in numerous interments in chambered tombs and caves in Belgium and France, as well as in Spain and Gibraltar. We may therefore conclude that at one period in the Neolithic Age the population of Europe, west of the Rhine and north of the Alps, was uniform in physique and consisted of the same small people as the Neolithic inhabitants of Britain and Ireland.”38