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‘Hobbit’ wrist bones suggest a distinct species
This week–
Hobbit hand waves away doubters Flores Island
INDEX FINGER INDEX FINGER
THUMB
African apes, older hominins and Homo floresiensis
TRAPEZOID
Modern humans and Neanderthals
“Hobbit” wrist bones look just like those of a chimpanzee, suggesting the species must have diverged from the human lineage well before modern humans and Neanderthals arose
BOB HOLMES
THE tiny, human-like creature living and using tools in Indonesia just 18,000 years ago really was a distinct species, not just a malformed modern human. That is the clear implication of a study which reports that the so-called “hobbit” had wrist bones almost identical to those found in early hominins and modern chimpanzees, and so must have diverged from the human lineage well before modern humans and Neanderthals arose. Palaeontologists have battled bitterly over the diminutive skeleton ever since its discoverers described it three years ago as a new species, Homo floresiensis. Its tiny brain simply did not fit with the current understanding
“The human wrist hasn’t looked like this for at least 800,000 years, and maybe much longer” 14 | NewScientist | 29 September 2007
of human evolution, particularly since no other hominin fossils in the last 3 million years – and none at all outside Africa – had such a small brain. This dissonance led sceptics to argue that the hobbit must be merely a modern human with some form of microcephaly. Most of the argument has centred around the skull, but much of the rest of the skeleton was excavated at the same time. When Matthew Tocheri, a palaeoanthropologist at the Smithsonian Institution in Washington DC, happened to see casts of the specimen’s wrist bones, he knew they told an important story. Tocheri, an expert in the evolution of the human wrist, could see right away that the hobbit’s wrist bones looked just like those of a chimpanzee or an early hominin such as Australopithecus – and had none of the specialisations for grasping that are seen in the wrist bones of
SOURCE: SCIENCE
TRAPEZOID
REUTERS
THUMB
modern humans (see Diagram). A statistical comparison came to the same conclusion (Science, DOI: 10.1126/science.1147143). “The modern human wrist hasn’t looked like this for at least 800,000 years, and maybe much longer,” says Tocheri. “It was immediately apparent to me that the hobbit is the real deal.” Developmental abnormalities such as microcephaly are unlikely to change the shape of the wrist bones, he adds, because the shape of these bones is laid down very early in development, long before the genes controlling growth rates become active. Other recent or soon-to-bepublished studies of the hobbit’s foot bones, upper arm and shoulder also suggest that its anatomy differed from that of modern humans. “As you add these up, you do certainly get a picture of something distinct and not human,” says Chris Stringer, an authority on human evolution at the Natural History Museum in London. However, Robert Martin, a primatologist at the Field Museum in Chicago who is the leading advocate of the microcephaly explanation, remains unconvinced. No one has studied the wrist bones of microcephalic humans, he notes, so it is pure conjecture to say they would not look like the hobbit’s bones. ●
THIS WEEK 50 YEARS AGO Tranquillisers for the people “It is impossible to estimate the number of people in the United States today who are living in a state of permanent tranquillity.” So runs a recent newspaper report. The quantity of tranquillisers consumed in the US and in the UK is beginning to worry medical people on both sides of the Atlantic. According to the Health News Institute, 35 million prescriptions for tranquillisers will be written in the US this year. In the state of Maryland alone, 11 per cent of its drug bill last year was for tranquillisers. The drugs, best known of which are chlorpromazine, reserpine and meprobamate, are being widely used in the treatment of psychiatric disorders both in hospitals and in general medical practice. Among the questions which arise when treatment of this sort is considered is whether it is safe for persons to go about their ordinary duties under the influence of tranquillisers. Should they, for example, drive cars? Or would they, perhaps, display a pathological lack of anxiety about red traffic lights? Another problem concerns their administration to children. It has been shown in animal tests, for example, that the indelible permanent attachment that offspring can make to their mother from the day they are born can be removed by taking meprobamate. On the credit side there is much to be said for tranquillisers. In one year 30,000 psychiatric hospital patients in New York state were given a course of chlorpromazine or reserpine. At the end of this time the hospital population had fallen by 452, in contrast to the average increase of 2000 for each year over the previous decade. It was the most abrupt recorded fall in the hospital population since 1909. Bearing this in mind, any ill effects of these drugs would need to be very real to counteract such an impressive achievement. From The New Scientist, 3 October 1957
–Unique– www.newscientist.com
Hobbit hand waves away doubters Flores Island
INDEX FINGER INDEX FINGER
THUMB
African apes, older hominins and Homo floresiensis
TRAPEZOID
Modern humans and Neanderthals
“Hobbit” wrist bones look just like those of a chimpanzee, suggesting the species must have diverged from the human lineage well before modern humans and Neanderthals arose
BOB HOLMES
THE tiny, human-like creature living and using tools in Indonesia just 18,000 years ago really was a distinct species, not just a malformed modern human. That is the clear implication of a study which reports that the so-called “hobbit” had wrist bones almost identical to those found in early hominins and modern chimpanzees, and so must have diverged from the human lineage well before modern humans and Neanderthals arose. Palaeontologists have battled bitterly over the diminutive skeleton ever since its discoverers described it three years ago as a new species, Homo floresiensis. Its tiny brain simply did not fit with the current understanding
“The human wrist hasn’t looked like this for at least 800,000 years, and maybe much longer” 14 | NewScientist | 29 September 2007
of human evolution, particularly since no other hominin fossils in the last 3 million years – and none at all outside Africa – had such a small brain. This dissonance led sceptics to argue that the hobbit must be merely a modern human with some form of microcephaly. Most of the argument has centred around the skull, but much of the rest of the skeleton was excavated at the same time. When Matthew Tocheri, a palaeoanthropologist at the Smithsonian Institution in Washington DC, happened to see casts of the specimen’s wrist bones, he knew they told an important story. Tocheri, an expert in the evolution of the human wrist, could see right away that the hobbit’s wrist bones looked just like those of a chimpanzee or an early hominin such as Australopithecus – and had none of the specialisations for grasping that are seen in the wrist bones of
SOURCE: SCIENCE
TRAPEZOID
REUTERS
THUMB
modern humans (see Diagram). A statistical comparison came to the same conclusion (Science, DOI: 10.1126/science.1147143). “The modern human wrist hasn’t looked like this for at least 800,000 years, and maybe much longer,” says Tocheri. “It was immediately apparent to me that the hobbit is the real deal.” Developmental abnormalities such as microcephaly are unlikely to change the shape of the wrist bones, he adds, because the shape of these bones is laid down very early in development, long before the genes controlling growth rates become active. Other recent or soon-to-bepublished studies of the hobbit’s foot bones, upper arm and shoulder also suggest that its anatomy differed from that of modern humans. “As you add these up, you do certainly get a picture of something distinct and not human,” says Chris Stringer, an authority on human evolution at the Natural History Museum in London. However, Robert Martin, a primatologist at the Field Museum in Chicago who is the leading advocate of the microcephaly explanation, remains unconvinced. No one has studied the wrist bones of microcephalic humans, he notes, so it is pure conjecture to say they would not look like the hobbit’s bones. ●
THIS WEEK 50 YEARS AGO Tranquillisers for the people “It is impossible to estimate the number of people in the United States today who are living in a state of permanent tranquillity.” So runs a recent newspaper report. The quantity of tranquillisers consumed in the US and in the UK is beginning to worry medical people on both sides of the Atlantic. According to the Health News Institute, 35 million prescriptions for tranquillisers will be written in the US this year. In the state of Maryland alone, 11 per cent of its drug bill last year was for tranquillisers. The drugs, best known of which are chlorpromazine, reserpine and meprobamate, are being widely used in the treatment of psychiatric disorders both in hospitals and in general medical practice. Among the questions which arise when treatment of this sort is considered is whether it is safe for persons to go about their ordinary duties under the influence of tranquillisers. Should they, for example, drive cars? Or would they, perhaps, display a pathological lack of anxiety about red traffic lights? Another problem concerns their administration to children. It has been shown in animal tests, for example, that the indelible permanent attachment that offspring can make to their mother from the day they are born can be removed by taking meprobamate. On the credit side there is much to be said for tranquillisers. In one year 30,000 psychiatric hospital patients in New York state were given a course of chlorpromazine or reserpine. At the end of this time the hospital population had fallen by 452, in contrast to the average increase of 2000 for each year over the previous decade. It was the most abrupt recorded fall in the hospital population since 1909. Bearing this in mind, any ill effects of these drugs would need to be very real to counteract such an impressive achievement. From The New Scientist, 3 October 1957
–Unique– www.newscientist.com