Thursday, August 7, 2014

Small Wonder, Big Blunder

Image: A comparison of the LB1 skull with that of a typical modern human, photo: David Ferguson, 2014, The Raw Story
“There is nothing like looking, if you want to find something. You certainly usually find something, if you look, but it is not always quite the something you were after.” 
― J.R.R. Tolkien, The Hobbit

The news was sensational, an unprecedented anthropological find: a mysterious new species of prehistoric humans, no bigger modern children, had been discovered in the Indonesian island cave of Liang Bua.

Named after Flores, the island where it was discovered, Homo floresiensis was a complete enigma. One specimen, LB1, included a complete skull and thighbones. All the other cave remains were fragments of several individuals.

LB1 was said to have a tiny cranium (only 380 milliliters or 23.2 cubic inches), housing a brain under a third of the average modern human's. Its thighs indicate it stood only 1.06 meters (3.5 feet) tall. When compared to Homo erectus and Australopithecus, it seemed utterly unique, surely an example of a previously unknown species.

Anthropologists have conclusively demonstrated that the first wave of prehistoric ancestors to leave Africa some 1.8 million years ago had been Homo Erectus, the so-called "wolves with knives", who crossed into Eurasia over the Levantine corridor and the Horn of Africa.

But Homo floresiensis seemed to have emerged with no known predecessors. How such a creature evolved completely outside documented human evolution was baffling, leaving anthropologists to surmise that it had arrived directly from Africa, and limited island resources had led to dwarfism as an adaptation - just as it had with the island's indigenous pygmy mammoths, pygmy elephants, pygmy hippos and others.

It was a romantic idea, the notion of "hobbits" living just 15,000 years ago. Unfortunately, it was a matter of making the evidence fit the narrative rather than vice versa.

An international team of American, Chinese and Australian researchers have demonstrated a much more plausible explanation: Homo Floriensis never existed. Penn State evolutionary geneticist Dr. Robert B. Eckhardt, along with University of Adelaide anatomy and pathology professor Maciej Henneberg and Chinese geologist and paleoclimatologist Kenneth Hsu examined LB1, the single known specimen. Instead of a new prehistoric human species with no ancestry, they found the "less strained explanation" was a typical human with Down syndrome.

The team immediately saw signs of such a developmental disorder, and further evidence supported this conclusion: a mismatch between the skull's left and right halves, the craniofacial asymmetry typical of Down syndrome. Such Down syndrome characteristics were only found in LB1 but none of the other Liang Bua remains, further indicating how atypical LB1 was.The creature's cranial volume and stature had been "markedly" underestimated: subsequent measurements consistently showed a cranial volume of 430 milliliters (26.2 cubic inches), a "significant" difference, and within the range of modern Indonesians with Down syndrome. Down syndrome patients are also comparatively short, consistent with the recovered thighbone.

Dr. Eckhardt's team eventually concluded the Liang Bua remains weren't sufficiently atypical to require creating an entirely new human species. Down syndrome, however, is one of the most common modern human developmental disorders, affecting more than one in a thousand babies worldwide.

Sources: Flores bones show features of Down syndrome, not a new 'hobbit' human, press release, David Pacchioli, August 4, 2014, Penn State University;
The Path Book I: Origins, 2014, Eric A. Smith   

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