Maybe the East [Africa] story of human origins is wrong. The traditional view of South Africa’s oldest hominin fossils is that they represent a separate evolutionary experiment that ultimately fizzled out. A. sediba could turn the tables and reveal, in South Africa, another lineage, the one that ultimately gave rise to humankind as we know it (indeed, sediba is the Sesotho word for “fountain” or “wellspring”).
William Kimbel of Arizona State University, who led the team that found the 2.3-million-year-old jawbone in Ethiopia, is having none of it. The idea that one needs a skeleton to classify a specimen is a “nonsensical argument,” he retorts. The key is to find pieces of anatomy that contain diagnostic traits, he says, and the Hadar jaw has features clearly linking it to Homo, such as the parabolic shape formed by its tooth rows. Kimbel, who has seen the Malapa fossils but not studied them in depth, finds their Homo-like traits intriguing, although he is not sure what to make of them. He scoffs at the suggestion that they are directly ancestral to H. erectus, however. “I don’t see how a taxon with a few characteristics that look like Homo in South Africa can be the ancestor [of Homo] when there’s something in East Africa that is clearly Homo 300,000 years earlier,” he declares, referring to the jaw.
What are we going to do with another homo in our evolutionary ladder?