John Hawks is one of the world's leading paleoanthropologists. He wrote:
For some people who follow human evolution news, recognizing “species” is really just about whether you’re a lumper or a splitter. Many people assume that the names of species are about ego, not evidence.
But nature presents us with real challenges, which still cause different scientists to approach the past with different assumptions. Let me give some examples.
Just today, I got notification of a new paper by Walter Neves and colleagues, in which they suggest that Australopithecus sediba and Homo naledi are actually South African representatives of Homo habilis. Some people might scoff at this—after all, the Dinaledi fossils are only 236,000–335,000 years old, while the latest-known H. habilis is around 1.6 million. But a young date for some fossils doesn’t bar them from from membership in a species with much older fossil representatives. Identity is tested with morphological evidence, not geological age.
Read more in this post "Arguing about species: Is it evidence, or ego?"