Gene, fossil data back diverse human roots

Just how modern humans first proliferated remains a great mystery of anthropology. Several recent fossil and genetic studies support the influential notion that a small population of Homo sapiens in Africa around 100,000 years ago began to spread, replacing humanlike species such as Neandertals.

A new study finds that an Australian H. sapiens skull (above center) is more similar to an Indonesian specimen (above left) than to a Middle Eastern one (above right). A European H. sapiens skull (below center) shares more traits with a Neandertal (below left) than with a Middle Eastern H. sapiens (below right). Wolpoff/Science

Two new investigations raise doubts about this out-of-Africa scenario.