Derek at Weapons of Mass Distraction links us to an article in the Telegraph on fossils and human evolution. The article mentions that in the past "fossil-hunters" were quick to place new fossil finds into different species so that today,
In other words, all those charts we saw in high school showing man evolving through several progressive stages until finally arriving at his present exalted state as Homo sapiens are now lining canary cages.
Notice here the subtle bit of professional CYA the good professor is indulging in. He claims on the one hand that all the fossils of early hominids are really H. sapiens, but not wanting to give succor to the creationists who have been saying precisely this for the last fifty years he notes that they nevertheless show "clear evidence of evolution." He uses the word evolution here to mean simple variability (microevolution), but the general reader will perhaps assume that he means that the fossils show clear evidence of having evolved from one basic form of life into a radically different form (macroevolution). By this locution he manages to undo a century and a half of Darwinian orthodoxy without exposing himself to the charge of heresy.
Henneberg's findings suggest that disputes among scientists as to the evolutionary relationships among the various types of fossil hominids are meaningless, as they ignore the possibility of huge differences within the same species.
In discussing the relationship of Neanderthals and humans, for instance, he states that "What evidence there is...is consistent with Neanderthals being from the same species as modern humans."
It's impossible to say how many of his colleagues agree with him although evidently some do:
Skeptics, of course, have long thought the evidence for numerous hominid species was tenuous. It was, after all, based upon purely structural differences. If the bones of various breeds of dogs were pried from different rock strata they'd doubtless be classified as different species based on morphological considerations, but, in fact, every dog from Great Danes to Daschunds are members of the same species. The problem is that the concept of species is slippery. Scientists define it as a reproductively isolated population of organisms, which means that if two members of a population can produce fertile offspring then they are members of the same species. There is, however, no way to tell by looking at a few bones whether or not members of the populations from which the bones came were capable of producing fertile offspring.
Perhaps one reason why scientists were so confident that the bones they had unearthed over the years were from different species of hominids is that they were absolutely convinced that man has evolved from an ape-like ancestor. If there is no question that species evolve over time, then bones taken from rock strata separated by millions of years just must be from different species. In other words, the reproductive isolation of the hominids was assumed, based on the theory of human evolution, and then the assumption that the hominids were different species was employed as evidence to reinforce the theory that humans have evolved from ape-like ancestors.
It's a nice, tight little circle.