From <em>PNAS</em>, a Scathing Rebuke to Hype over <em>Homo Floresiensis</em>, Lost &quot;Hobbit&quot; Species - Evolution News & Views

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From PNAS, a Scathing Rebuke to Hype over Homo Floresiensis, Lost "Hobbit" Species

Hobbit.jpg

As our friend Denyse O'Leary has pointed out, Darwinian expectations would be fulfilled by the discovery of other human species living alongside modern humans:

If Darwinian evolution is true, the human race should evolve into different species. Indeed, Darwin said that in the Descent of Man. It is a feature, not a bug. But there is no clear evidence that it is happening. Thus, it would be most helpful to the argument if a new species (i.e., clearly human but not Homo sapiens) was unearthed. Or at least, if the evidence was mixed, a species that could be argued into existence.

Homo floresiensis, the meter-high hobbit-like race conjectured on the basis of bones discovered on the Indonesian island of Flores, seemed to fulfill that expectation. Many hopes were pinned on this diminutive person, called LB1 after the name of the cave, Liang Bua, where she was found. Dating back to only 18,000 years ago, the specimen of a female was coeval with modern humans, but not like us. Or was she?

A new paper in the Proceedings of the National Academy of Sciences dashes such hopes in scathing fashion. Pretty much everything that seemed to be diagnostic of a new species living so in hauntingly recent times turns out to be more indicative of a modern human afflicted by Down syndrome.

From "Evolved developmental homeostasis disturbed in LB1 from Flores, Indonesia, denotes Down syndrome and not diagnostic traits of the invalid species Homo floresiensis":

The population that has become known as Homo floresiensis has been described as "the most extreme human ever discovered." Specimen LB1 from Liang Bua Cave is unusual, but craniofacial and postcranial characteristics originally said to be diagnostic of the new species are not evident in the other more fragmentary skeletons in the sample that resemble other recent small-bodied human populations in the region (including the Andaman Islands, Palau, and Flores itself). Here we demonstrate that the facial asymmetry, small endocranial volume, brachycephaly, disproportionately short femora, flat feet, and numerous other characteristics of LB1 are highly diagnostic of Down syndrome, one of the most commonly occurring developmental disorders in humans and also documented in related hominoids such as chimpanzees and orangutans.

They conclude:

The Liang Bua Cave skeletal remains demonstrate the existence on Flores, Indonesia, of a small-bodied Australomelanesian population that conforms with its regional and temporal provenance.  Against this background, the abundant pathological signs that mark cranial and postcranial morphology of the LB1 individual establish a very high probability of that specimen manifesting [Down syndrome]. Regardless of any specific diagnosis, DS or other, for its array of morphologies to be considered typical for a new species, the taxon's defining feature would have to be an abnormality. Because teratological individuals are barred as type specimens by the International Code of Zoological Nomenclature (75), documentation of serious anomalies in LB1 leaves Homo floresiensis as a nomen nudum.

That last sentence means that abnormal specimens don't count in the identification of a new species, leaving Homo floresiensis a "naked name" (nomen nudum), an empty designation, a hat without a man (or a hobbit) under it.

The paper finds "multiple paradoxes" in the case including: "mythologizing substituted for testable hypotheses" and "media 'propagation of half-informed, sensational treatments' [implying] scientific consensus for what is mainly repetition of conjecture."

The science media, regarded as a source of gospel truth by many, engage in "mythologizing" and "'sensational treatments' [implying] scientific consensus for what is mainly repetition of conjecture." As I said before in the context of revelations that scientific researchers are human beings just like you and me, those are words to imprint in your memory.

What's true of professional scientists is also true of science journalists: they are not Olympian deities gifted with extraordinary objectivity, somehow above the failings of lesser men. It falls to the rest of us, then, to critically examine what they say rather than taking it all at face value.

If you hear something repeated often enough, like the Hobbit of Flores story, it's hard to resist the impression that it must be true. Credulousness, however, is a very human shortcoming, virtually a diagnostic trait.

I'm on Twitter. Follow me @d_klinghoffer.

Photo: Reconstruction of Homo floresinsis, Smithsonian Museum of Natural History/Wikipedia.