Until the 1990s it was common to place these specimens either in H. erectus or into a broad category along with Neanderthals that was often called archaic H. sapiens (Homo sapiens). A problem with the latter designation was the growing recognition that Neanderthals (Neanderthal) were unique to and relatively isolated in Europe and western Asia. It therefore became common to categorize the Neanderthals as a separate and morphologically well-defined species, H. neanderthalensis. At the same time, lumping specimens such as those found at Bodo and Petralona with modern H. sapiens would have created an unreasonably heterogeneous species, since modern H. sapiens is remarkably homogeneous in morphology and behaviour and differs strongly from archaic Homo species. Designating the Bodo and Petralona specimens as H. heidelbergensis emphasizes the uniqueness of modern H. sapiens (Homo sapiens), Neanderthals, and H. erectus. Using this taxonomy, it appears to many researchers that H. heidelbergensis is the common ancestor of both Neanderthals and modern man, with the transition from H. heidelbergensis to H. sapiens having occurred in Africa between 300,000 and 200,000 years ago.