Monday, June 29, 2009

Another Potential Edit to Human Evolution

I'm a tall person. With a very rare exception, I stand a good head or two taller than most other folks at any random cocktail party.

I've never given much thought to how much I stand apart, though comments from strangers looking for something to start a conversation with have prompted contemplation. A word of advice: If you tell me I'm tall, don't be upset should I tell you how short you are. Observation of the obvious won't win you any points.

What if there was a division of society based on physiology, instead of race or intelligence, where height above all else was the paramount attribute of choice? Anyone over six foot would be 'relocated.' Perhaps I would be sequestered to Baja California with most of the NBA and several west Asian Aryan-types. Our gene-pool would be segregated from polluting 'normal' society. However, at 5 foot 1, my wife would not be keeping me company.

In 2004, skeletal remains of an adult woman were found on the remote, Balinese island of Flores. What makes her remarkable was her size... only 3 feet tall. Recognized as a previously unknown development of pre-history humanoids, scientists labeled the remains Homo Floresiensis, or Flores Man, and have named the remains, the 'Hobbit.'

"To find that as recently as perhaps 13,000 years ago, there was another upright, bipedal—although small-brained—creature walking the planet at the same time as modern humans is as exciting as it was unexpected," said Peter Brown, a paleo-anthropologist at the University of New England in New South Wales, Australia. Brown is a co-author of the study describing the findings, which appeared in the October 2004 issue of the science journal Nature.

Image of Flores skull
Levels of the Hobbit's sophistication surpassed her contemporary, Homoerectus, primarily in the form of tools found near pygmy-elephant remains. The hand-worked stone implements of Flores are much more definitive than those associated with Erectus, whose tools where bulkier and designed for multi-use. Flores' tools were highly specialized, including spear and javelin spearheads, as well as scrapers and marrow 'extractors'... tools associated with cro-magnon development. Amazingly, the Hobbit's brain size was smaller than any pre-human ancestor, more than half the volume of Erectus. Flores' brain was no larger than a chimpanzee.

"It is totally unexpected," said Chris Stringer, director of the Human Origins program at the Natural History Museum in London. "To have early humans on the remote island of Flores is surprising enough. That some are only about a meter tall with a chimp-size brain is even more remarkable. That they were still there less than 20,000 years ago, and [that] modern humans must have met them, is astonishing."

Not only has the size of the woman astonished the scientific community, but the geography of her habitat is incredible as well. Flores is a small island, not a place that would be identified as a possible location for the development of 'alternative' humanoid development. Though dwarfism is prevalent among isolated island communities, the technology base of modern man allows for a 'spread' of genetic breeding through travel. 18,000 years ago, this was not be the case.

The limiting geographic range suggests the physiology of the 'Hobbit' might derive from abnormal growth, perhaps even microcephaly. 'Mutation' through inbreeding certainly would have been a danger, as geologic evidence suggests a massive volcanic eruption sealed its fate 12,000 years ago, along with other unusual island species like the dwarf elephant species, stegodon. This theory, however, would place the age of the remains at roughly three-years old. The remains of the Flores woman, however, are estimated to be around eighteen-years-old based on the wear to the teeth as well as fusions in the skull.

"This finding really does rewrite our knowledge of human evolution," said Stringer.

Alternate theories suggest Flores Man doesn't belong in the genus Homo at all, even if it was a contemporary to Erectus. But other explanations seem elusive, and this denial with the absence of counter-evidence is nothing new to the paeleological community. Early Java man was first thought to be an arthritic gibbon.

"I don't think anybody can pigeonhole this into the very simple-minded theories of what is human," says anthropologist Jeffrey Schwartz of the University of Pittsburgh. "There is no biological reason to call it Homo. We have to rethink what it is."

This much is clear: The Hobbit's teeth and skull show it was an adult, and the shape of the pelvis is female. The skull is wide like that of Homoerectus. But the sides are rounder and the crown traces an arc from ear to ear. The lower jaw contains large, blunt teeth and roots much like and even older ancestor, Australopithecus. The eye sockets are large and round, but unlike other members of the Homo genus, it has hardly any chin or browline. The skeletal frame looks as if it walked upright, but the pelvis and the shinbone have primitive, even apelike features.

Bones from the species' feet and hands have not yet been found. Delicate artifacts found in the cave were described as "toy-sized" versions of stone tools made by Homoerectus. They suggest that Flores Man retained intelligence and dexterity to flake small weapons with sharp edges, even if its body shrunk over time. Osteoporosis?

Whatever the case may be concerning how the Hobbit fits into the tree of human development, this much is certain: she comes from a branch that many scientists are nervous to shake. Who knows what else might fall out.

Professor Bert Roberts down the hole

where the 18,000-year-old skeleton was found.

The white layer is volcanic ash from an

eruption that may have wiped out the species.

University of Wollongong


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