Homo Heidelbergensis - Divergent Evolution

Divergent Evolution

Because of the radiation of H. heidelbergensis out of Africa and into Europe, the two populations were mostly isolated during the Wolstonian Stage and Ipswichian Stage, the last of the prolonged Quaternary glacial periods. Neanderthals diverged from H. heidelbergensis probably some 300,000 years ago in Europe, during the Wolstonian Stage; H. sapiens probably diverged between 200,000 and 100,000 years ago in Africa. Such fossils as the Atapuerca skull and the Kabwe skull bear witness to the two branches of the H. heidelbergensis tree.

Homo neanderthalensis retained most of the features of H. heidelbergensis after its divergent evolution. Although shorter, Neanderthals were more robust, had large brow-ridges, a slightly protruding face, and lack of prominent chin. With the possible exception of Cro-Magnon Man, they also had a larger brain than all other hominins. Homo sapiens, on the other hand, have the smallest brows of any known hominin, are tall and lanky, and have a flat face with a protruding chin. H. sapiens have a larger brain than H. heidelbergensis, and a smaller brain than H. neanderthalensis, on average. To date, H. sapiens is the only known hominin with a high forehead, flat face, and thin, flat brows.

Some believe that H. heidelbergensis is a distinct species, and some that it is a cladistic ancestor to other Homo forms sometimes improperly linked to distinct species in terms of populational genetics.

Some scenarios of survival include:

• H. heidelbergensis > H. neanderthalensis
• H. heidelbergensis > H. rhodesiensis > H. sapiens idaltu > H. sapiens sapiens

Those supporting a multiregional origin of modern humans envision fertile reproduction between many evolutionary stages and homo walking, or gene transfer between adjacent populations due to gene passage and spreading in successive generations.