The second theory that has been advanced to explain the sameness of a number of fundamental ideas and inventions is based on the assumption that they represent old cultural achievements belonging to a period previous to the general dispersion of the human race. This theory is based on the universal distribution of certain cultural elements. Obviously it can apply only to features that occur the world over; for, if we should admit the loss of some of them in the course of historical development, the door would be open to the most fanciful conclusions. A few ethnological data seem to favor this theory, and make us inclined to believe that some of the universal traits of culture may go back to a very early time before that dispersion of mankind which is demanded on biological grounds. Most important among these is perhaps the occurrence of the dog as a domesticated animal in practically all parts of the world. It is true that in all probability native wild dogs constitute the principal ancestry of the dogs of the various continents; but nevertheless, it seems plausible that the living-together of man and dog developed in the earliest period of human history, before the races of northern Asia and America separated from those of southeastern Asia. The introduction of the dingo (the native dog) into Australia seems to be most easily explained when we assume that it accompanied man to that remote continent. Other very simple activities may perhaps be derived from achievements of the earliest ancestors of man. The art of fire-making, of drilling, cutting, sawing, work in stone, belonged probably to this early age, and may have been the heritage on which each people built up its own individual type of culture (Weule). If archæological investigations should show that implements and other evidences of human achievement are found in a geological period during which mankind had not attained its present world-wide distribution, we should have to infer that these represent the early cultural possessions of man, which he carried with him all over the world. In this lies the great and fundamental importance of the eolithic finds that have been discussed so extensively during the last few years. Language is also a trait common to all mankind, and one that therefore may have its roots in earliest times. The activities of the higher apes seem to favor the assumption that certain arts may have belonged to man before his dispersion. Their habit of making nests, that is, habitations, the use of sticks and stones, point in this direction. All this makes it plausible that certain cultural achievements date back to the origin of mankind. The defenders of this theory, like Weule and Graebner, also believe that a sporadic occurrence of certain inventions like the boomerang, among races that are held to be akin in descent, may have originated before the differentiation and dispersion of these races.