Latest Word: Prehistoric Hobbits were not Victims of a growth Disorder - April 28th, 2008
Scientists at Florida State University in Tallahassee say that remains of Homo floresiensis, also known as hobbits, do not show any sign of growth disorders, refuting earlier claims that hobbits were pygmy Homo sapiens that suffered from a growth disorder.
Lead researcher Dean Falk and her Florida State colleague Angela Schauber came to this conclusion after studying computer-generated reconstructions of the fossilized skulls of the small islanders. They suspect that Homo floresiensis especially as represented by a partial skeleton called LB1adapted to a challenging island environment by evolving into a smaller but proportionally equivalent version of an ancestral species, possibly Homo erectus.
LB1 didn't have any of the growth pathologies that have been attributed to it, Falk said.
A study unveiled last year suggested that LB1 exhibits 33 skeletal symptoms of Laron Syndrome, a type of insensitivity to growth hormones. Besides a reduction of face and limb size, this condition includes a round protrusion of the forehead and a depressed ridge on top of the nose. Falk, however, says that measurements, photos, and 3-D computer tomography reconstructions of LB1 do not show any similarity to published data on the anatomy of Laron Syndrome.
She says that LB1 displays unique skull and tooth traits. She says that it also possesses whopping long feet relative to body size, in contrast to the typically small feet observed in Laron Syndrome. Apart from this, preliminary findings also show that LB1 did not suffer from one form of microcephaly, a genetic growth disorder, or from cretinism, a nutritionally influenced growth disorder.
Schauber used museum skeletal collections to establish that certain species of foxes and mice have evolved into proportional miniatures of larger counterparts. The same process could apply to Homo floresiensis, she says. She says that island gray foxes, found on islands off the California coast, show the same brain size relative to body size as larger mainland foxes do. The research also showed that dwarf little mice matched the relative brain size of much larger, normal-sized mice, she adds.
Schauber says that LB1 shows no signs of having had a relative brain size distorted by any growth disorder, and could well have been a proportional dwarf, as observed in foxes and mice. Robert Eckhardt of Pennsylvania State University in University Park, however, still regards LB1 as a pygmy Homo sapiens that suffered from a still-undetermined growth disorder.
About 400 dwarfing syndromes exist in people today, leaving an extensive list for Falk and her fellow hobbit advocates to consider for LB1, Eckhardt said at the annual meeting of the American Association of Physical Anthropologists, where Falk and Schauber presented separate papers. Primitive-looking features of LB1s wrist and arms actually fall within the range of variation for people today, Eckhardt argued. Homo floresiensis is an imaginative composite, he concluded. (ANI)
From Afarensis, Anthropology, Evolution and Science
Homo floresiensis: Walk Like a Clown?
Tolkien's hobbits walked an awful long way, but the real "hobbit", Homo floresiensis, would not have got far. Its flat, clown-like feet probably limited its speed to what we would consider a stroll, and kept its travels short, says Bill Jungers, an anthropologist at the State University of New York in Stony Brook. "It's never going to win the 100-yard dash, and it's never going to win the marathon," he says. He presented his conclusion at last week's meeting of the American Association of Physical Anthropologists in Columbus, Ohio.
By analysing the nearly complete left foot of an 18,000-year-old hobbit skeleton dubbed LB1, found on the Indonesian island of Flores , Jungers' team estimated the length of the hobbit's feet, which were unusually large for its meter-high frame. "Sort of like a young girl wearing her mum's shoes," Junger says.
And because of their long feet, Homo floresiensis probably had to bend its knee further back than modern humans do, resulting in a sort of high-stepped gait. "You would watch these hobbits walk and say they're walking a little funny," Jungers says. The foot had other peculiar features as well. For one, its big toe was quite short compared with the others, similar to earlier hominids such as Australopithecus. However, the shape of the toes, even the short big toe, is like modern human ones, Jungers says. "It has a human morphology and an ape-like proportion," he says. Jungers and other researchers who claim the hobbit was a distinct species from Homo sapiens point to the foot as further evidence supporting their theory. It has been suggested that the hobbit suffered from a severe block to growth known as cretinism or a disease called microcephaly that leads to miniaturized heads. "It puts another nail in the coffin of the disease hypothesis," says Henry McHenry, an anthropologist at the University of California, Davis who saw the presentation. But the feet don't solve the bigger mystery of where Homo floresiensis originated, McHenry says. "It's so strange," he muses.
Hopeful, they had a podiatrist in their health plan as well!
From New Scientist, # 12:30 16 April 2008 # NewScientist.com news service # Ewen Callaway
Were the Hobbits Cretins?
As reported by ScienceNow, a new study conducted by Peter Obendorf and Benjamin Kefford of the RMIT University of Melbourne and Charles Oxnard of the University of Western Australia at Crawley concluded that the small stature of the Homo floresiensis was not the result of genetic defects. The study, published in the journal Proceedings of the Royal Society B, suggests that the hobbits' size was caused by a condition known as cretinism. This is due to a lack of iodine. Comparing the pituitary flossa in a hobbit skull with individuals suffering from cretinism, they found a significant match and thus suggested a new theory. The remains of twelve hobbits were originally found in a cave in Liang Bua. Obendorf stated that it is an area where people still suffer from goiters that results from iodine deficiency. The new study even mentions that local myths include stories of tiny people who lived in caves. While it may be too early to discard the microcephaly hypothesis altogether, the case for hobbits being real humans is much stronger than before. We should probably do well to forget the image of an ape-like man carrying a furry animal on his shoulder and start describing hobbits as real people. It seems that the distinction between hobbits and humans is found only in Tolkien's Midde-Earth but not on this earth.
Sarah would not be amused with these cretins!
Ancient Bones of Small Humans Discovered in Palau
Thousands of human bones belonging to numerous individuals have been discovered in the Pacific island nation of Palau. Some of the bones are ancient and indicate inhabitants of particularly small size, scientists announced today. The remains are between 900 and 2,900 years old and align with Homo sapiens, according to a paper on the discovery. However, the older bones are tiny and exhibit several traits considered primitive, or archaic, for the human lineage. "They weren't very typical, very small in fact," said Lee Berger, a paleoanthropologist at the University of Witwatersrand in Johannesburg, South Africa. Berger was on vacation in 2006, kayaking around rocky islands about 370 miles (600 kilometers) east of the Philippines, when he found the bones in a pair of caves. The caves were littered with bones that had been dislodged by waves and piled like driftwood. Others had remained buried deep in the sandy floor, and more, including several skulls, were cemented to the cave walls. Berger returned later that year with colleagues to excavate some of the remains with funding from the National Geographic Society. (National Geographic News is a division of the National Geographic Society.) A paper to appear tomorrow in the Public Library of Science journal PLoS ONE describes the findings and what they suggest about small-bodied humans. Interpreting the Bones Two sets of human bones were found in the Palauan caves. The most recent remains were found near the entrance to one of the caves and appear normal in size. Older bones found deeper in the caves are stranger and much smaller. The smaller, older bones represent people who were 3 to 4 feet (94 to 120 centimeters) tall and weighed between 70 and 90 pounds (32 and 41 kilograms), according to the paper.
The diminutive people were similar in size to the so-called hobbit discovered in National Geographic Society-supported excavations on the Indonesian island of Flores in 2003. Scientists classified the hobbit as a separate human species, Homo floresiensis. According to Berger, the estimated brain size of the early Palauans is about twice the size of the hobbit brain. Several other features, including the shape of the face and hips, suggest that the Palauan bones should be classified as Homo sapiens. If the interpretation of the Palauan remains is correct, the find may add more fuel to the debate over whether the Flores hobbit is a unique species, Berger said. Aside from being tiny, the Palauan bones show that some of these people lacked chins and had deep jaws, large teeth, and small eye sockets, according to the paper. Some of these features were considered important in originally distinguishing the hobbit as a unique—and archaic—species, Berger said. But the Palauan remains suggest these features may just be a consequence of insular dwarfism, a shrinking process that some scientists attribute to the stresses of a small island environment.
Palau lacks indigenous terrestrial mammals and large reptiles that early Palauans might have used for food. Archaeological records indicate fishing was not a local activity until about 1,700 years ago, around the time bigger bones appear in the caves. The early Palauans' limited diet, combined with a tropical climate, absence of predators, a small founding population, and genetic isolation, may have produced "these very odd features and very small body size," Berger said.
William Jungers, an anthropologist at Stony Brook University in New York and a former National Geographic grantee, stands by his conclusion that the hobbit is a unique species. He notes that the small bones, large teeth, lack of a chin, and other features that characterize the early Palauans as well as the hobbits can be found in other small-bodied human populations around the world. But "the smallest-bodied people on Earth do not converge on the proportions and various aspects of morphology of the hobbits," Jungers said. Jungers points out that the hobbit is distinguished from modern humans by jaw structures called transverse tori, which are seen in human ancestors, such as australopithecines and some Homo erectus fossils, he noted. Chris Stringer, lead researcher in the human-origins program at London's Natural History Museum, points to other defining characteristics in the hobbits' feet, teeth, and shoulder and wrist bones. Based on this evidence, he says, "I still believe that the Flores material is something distinct and primitive."
Berger says his team has yet to analyze the shoulder, feet, and wrist bones in their Palauan sample and thus cannot comment on how they compare to the hobbit bones. A Disease Factor? Unlike the Palauan bones, the hobbit fossils include a skull with an exceptionally small braincase. Its volume is much smaller than that of small-bodied peoples living today on other Pacific islands and in the forests of Africa. It is also smaller than that of the early Palauans. Some scientists argue that the unusually small brain volume of the hobbit makes it not a unique species but rather a small-bodied Homo sapiens with microcephaly, a genetic disease that causes small brains and other abnormalities. A team of researchers from Australia recently reported that the unusual limbs of Homo floresiensis may also have been influenced by disease. The distortions, they claim, are sometimes seen in the offspring of a normal, small-bodied human female with goiter. Berger says his team's findings might support these disease arguments. But they have yet to find an individual in their sample who had one of these diseases and therefore can't make a comparison.
The Debate Continues Dean Falk is an anthropologist at Florida State University in Tallahassee who received National Geographic funding to compare the Flores skull with both microcephalics and modern humans without disease. She and colleagues from the Mallinckrodt Institute of Radiology concluded in a study published last year that the hobbit was not microcephalic. Falk said the finding closed the microcephaly argument. The Palauan remains, she added, are just a set of small bones, representing small-bodied people. ""But being small does not make one comparable to Homo floresiensis," she noted. "It makes one small—period."
Steven Churchill, a paleontologist at Duke University and co-author of the new study, says the Palauan discovery expands the known range of variation in modern humans in Southeast Asia, adding context in which to interpret the hobbit fossils. Several scientists, he adds, continue to believe "there's something wrong with Flores." One of these scientists is Robert Martin, the curator of biological anthropology at the Field Museum in Chicago, Illinois. He says it's well known that small-bodied human populations exist in Southeast Asia. A community of pygmies now lives near the Flores hobbit site in the village of Rampapasa, so finding small-bodied Homo sapiens on Palau, he says, "is no surprise." From Martin's perspective, the problem with the classification of the hobbit as a separate species is that it is based largely on the brain size of "one microcephalic individual in Flores. … Body size is really a separate issue." According to Berger, the new findings suggest that "you don't have to look very far to find the facial and dental characters thought to be unique in Flores." If traits such as those found among the early Palauans are common on islands, he said, then scientists who want to name a new species in the human lineage will have to present "a much better case built on a lot more fossils before the world will buy it." ----------- news.nationalgeographic.com
Homo floresiensis: More Microcephaly Claims
According to New Scientist a new study will be published in Science indicating that Homo floresiensis was a microcephalic member of a dwarfed population (splitting the difference I guess). The study modeled dwarfism in a range of mammals:
"As they dwarf, species' brain sizes decline far more slowly than body size," says Ann MacLarnon from Roehampton University, UK, who modeled dwarfing in a range of mammals from dogs to elephants with a team from the Field Museum, Chicago, US. "Brain size is key to a mammal species' identity," she says. There is, for example, hardly any difference in brain size between the smallest modern humans, the 1.4-metre Bambuti people of Congo's Ituri Forest, and the tallest, the 2-metre Masai of east Africa.
The team calculated that a dwarfed Homo erectus with a 400cc brain would weigh just 2 kilograms. "That's one-tenth of what the Flores people must have weighed," she explains. The only way to explain the discrepancy, the team believes, is microcephaly.
Morwood disputes this:
"Although we only have one cranium," says Morwood, "the other bones we found show that LB1 was a normal member of an endemically dwarfed hominid population." The distinctive traits of reduced body mass, reduced brain size and short thick legs mirror those found in other island endemic populations of large mammals, Morwood says. He calls the microcephaly explanation "bizarre". It ignores other evidence from Liang Bua and the literature on island endemic evolution, he says.
MSNBC also has an article on it:
In a response to their paper, researchers led by Dean Falk of Florida State University called Martin's assertions "unsubstantiated." Martin's comparison of LB1 with the skulls of microcephalics lacks crucial details, Falk stated. Falk also challenged Martin's comment that such a small brain size would indicate an extremely tiny creature based on the calculations for dwarf versions of other animals. It would be surprising if the dwarf version of an early human scaled down in the same way as an elephant, for example, Falk responded. Falk and his co-authors argued that the size of LB1's brain is consistent with that of adult microencephalics.
Weird, first Falk is qouted as dismissing the microcephaly argument then supporting it, I think the reporter was confused...
National Geographic has more:
The disease has dozens of different forms, Martin says. But Falk and colleagues only compare the Flores fossil to one poorly matched microcephalic skull of a modern human.
Martin's team, by contrast, identified other microcephalic skulls that more closely resemble the Flores fossil skulls, he says. Falk acknowledges that her team only examined one skull. But she adds that the evidence that Martin's team's skulls are better matched is poorly illustrated in Martin's paper. Regardless, Falk adds, her team is finishing up an in-depth analysis on microcephaly. "We're confident that [the hobbit skull] is not a microcephalic," she said.
Also, Falk and her colleagues noted in their original paper that normal dwarfing of Homo erectus could not explain the Flores fossils. Rather, they suggested the hobbits resulted from dwarfing of apes or australopithecines, earlier human ancestors.
Potts says Martin and colleagues are primarily reacting to the original interpretation of the hobbit find, published in 2004 in the journal Nature. That study said that the Flores fossils represent island dwarfing in Homo erectus and not dwarfing of an ape or australopithecine.
"So what would island dwarfing in an ape look like?" Potts asked. "We don't know--that's one of the big gaps of this whole thing."
In addition, Potts says, Martin and colleagues' suggestion that the Flores skull represents a microcephalic modern human is unsupported by recent studies on leg and shoulder fossils from Flores that suggest similarities to earlier human ancestors.
"We're dealing with something unprecedented in modern humans," Potts said.
"[The hobbit is] either a representative of a unique and unreported range of variation in a modern human, or it's a new species that seems to be derived from an earlier ancestor. "That second idea is more in line with the original interpretation and probably the safest at this stage," he continued. "But it's a wonderful mystery."
Posted on: May 18, 2006 3:57 PM, by afarensis, FCD