The dividing line between ape and man is drawn partly upon physical grounds, but the greatest difference is a cultural one. Men possess and transmit culture, a process ordinarily regarded as involving language. Men make tools; apes do not. The smallest, crudest, and perhaps earliest of the _Australopithecines_ have long been championed by Dart, who argues most persuasively that they were at least tool users, if not toolmakers. With their remains were those of other animals, a source of bones for picks and clubs, teeth for cutting and scraping, and so on. Perceiving crude, ready-made tools of bone, tooth, and horn, Dart coined the term “osteodontokeratic” for this pre-Stone Age assemblage.[15] This nomenclature was criticized by physical and cultural anthropologists alike. Whether this “culture” of the _Australopithecines_ is real or—as many believe—imagined, there is no doubt about the equipment of _Zinjanthropus_. Associated with his bones are stone tools of the Oldowan culture, an Abbevillian-level, “Pre-Chelles-Acheul” industry of worked stone flakes. In the words of his discoverer, Dr. L. S. B. Leakey, here was the oldest maker of stone tools so far known. By 1960, the skull of _Zinjanthropus_ had not been fully studied. In certain of its features, it favors _Paranthropus_, _Australopithecus_, or _Homo_. On first glance it seems as nearly human as Java man, which Leakey says it predates.[16] There are two main difficulties in placing the _Australopithecines_ on the line of human evolution. Although they might be said to resemble man more than the apes, they actually resemble neither, for their features are so specialized that it is difficult to conceive of them as ancestral to either. It is difficult, too, to place them in geologic time. Except for _Zinjanthropus_, who clearly belongs to the upper part of the Lower Pleistocene, most of the _Australopithecines_ have been recovered from caves, fissures, or other places where there is no stratification. They are all much too old to be placed in time by some of our more precise dating techniques, such as the radiocarbon method. Non-primate bones found with them are typical of animals that in Europe ranged all the way from the Mid-Pliocene to the Mid-Pleistocene. South Africa is a cul-de-sac, relatively untouched by the Ice Age. The abundance and variety of animals surviving today in most of Africa south of the Sahara are reminiscent of the Pleistocene elsewhere. The index fossils of other lands are not much use when it comes to dating _Australopithecus_.