It is one of the best-known stories in science: the evolution of mankind from ape-like creatures to modern humans via knuckle-grazing cave-dwellers.
Now it has been blown apart by the first comprehensive study of all the fossils, which has revealed that they are probably all variants of Homo sapiens.
This is the type of dumb illustration often included with these stories & it was this time as well.
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The discovery comes as fossil-hunters in Indonesia continue to defend claims to have found yet another new species of human, dubbed "Hobbit Man". If true, the diminutive creature would join such famous specimens as Lucy, Java Man and the Neanderthals in the complex family tree of mankind.
The findings have significant implications for the often bitter debates between fossil-hunters about the significance of their finds. While they no longer bicker over the so-called "Missing Link" - the now-derided idea of a creature linking humans to chimpanzees - experts continue to argue over the relationship between Australopithecines and early humans, and between Neanderthals and modern humans.
The number of human species claimed by fossil-hunters now stands at around 10, while the total number of human-like species exceeds 50. Such claims have long been based on supposedly significant differences in sizes and shapes of fossil bones.
Now they have all been thrown into doubt by research showing that the differences lie within the range expected for just a single species.
Professor Maciej Henneberg, of the University of Adelaide, a world authority on fossil human anatomy, made the discovery after analysing the skull sizes and estimated body weights for all of the 200 identified specimens of human-like fossils known as hominims.
These span the entire history of humans, from the emergence of so-called Australopithecines with an upright stance more than four million years ago to neolithic modern humans from around 10,000 years ago.
|Prof Maciej Henneberg|
Prof Henneberg found that the fossils show clear evidence of evolution, with substantial increases in both skull sizes and body-weight. However, he also found that the fossils show no evidence of being anything other than a single species which had grown bigger and smarter over time.
According to Prof Henneberg, the much-vaunted differences in fossil size used to identify "new" species all lie within the normal range expected for one species. Plotted out as a graph, they form the classic bell-shaped curve found using data from modern humans.
Reporting his findings in the current issue of the Journal of Comparative Human Biology, Prof Henneberg concludes:
"All hominims appear to be a single gradually evolving lineage containing only one species at each point in time."
The findings have big implications for the often bitter debates between fossil-hunters about the significance of their finds. Experts have long bickered over the relationship between Australopithecines and early humans, and between Neanderthals and modern humans.
Prof Henneberg has said that the new results suggest such disputes are meaningless, as they ignore the possibility of huge differences within the same species. He said they also raise doubts about the reliability of bones in identifying new human species: "There is no precise way in which we can test whether Julius Caesar and Princess Diana were members of the same species of Homo sapiens".
According to Prof Henneberg, the study highlights the scant evidence for so many of the claimed new species of human. "Considering that there are only about 200 specimens in total, if these really do represent ten different species, that makes an average of just 20 specimens per species".
He added that only a single skull had been found for the "Hobbit Man" of Indonesia.
Other authorities hailed Prof Henneberg's findings as a much-needed reality check. "Clearly there is a need to be more aware of the possibility of variation - but that is not the inclination today," said Geoffrey Harrison, emeritus professor of biological anthropology at the University of Oxford.
"It has been a problem because the discoverers have usually put so much effort into finding the evidence, so they want it to be important".
Professor Chris Stringer, a leading expert on human fossils at the Natural History Museum, London, said even Neanderthals were not significantly different in skull or body size from modern humans.
However, he added that they do differ in other details, such as inner ear bones. He said: "The argument they are a different species is, of course, only a hypothesis, but comparisons of skull shape published recently certainly show they are as different from us as monkeys and apes are different from each other".
According to Prof Henneberg, there are fewer than 30 examples of Neanderthals on which to base any conclusions. What evidence there is, however, is consistent with Neanderthals being from the same species as modern humans.
He added that the never-ending announcements of new species said more about those making the claims than about human evolution. "The problem is there are far more palaeontologists than fossil specimens".