This Week PAGE 1390 1395 1396 1401 1402 Martian ice, The guts or lava? of HIV NEWS infections

PALEOANTHROPOLOGY mates, and extinct hominids. They found that, relative to its overall size, the brain of has very large temporal Small but Smart? Flores Hominid lobes, brain regions associated in living peo- ple with understanding speech and hearing. Shows Signs of Advanced Brain Even more dramatically, the hominid has highly folded and convoluted frontal lobes, The startling announcement last October of an inside it, the team made a virtual endocast areas of the brain just under the forehead that 18,000-year-old skeleton of a new species of from computerized tomography scans. The are implicated in higher cognition. “There human posed a paradox: Despite having a original discovery team, including co-authors are two huge convolutions,” Falk says. “I brain no larger than a chimp’s, the diminutive Michael Morwood and Peter Brown of the haven’t seen swellings like this before in any hominid from the Indonesian island of Flores University of New England in Armidale, Aus- [extinct] hominid endocasts,” including showed signs of advanced intelligence, tralia, had the skull scanned at a hospital in the those of Homo erectus. The most convoluted including hunting with sophisticated stone Indonesian capital of before the bones region is in the most forward-projecting part tools. That paradox may now be solved. A were temporarily moved last fall to of the frontal lobe, called the frontal pole. detailed study of the cranium of (see sidebar). Falk identifies this region as Brodmann’s Homo floresiensis, published The researchers com- area 10, which is expanded in modern online this week by Science pared the endocast to vir- humans and is involved in undertaking ini- (www.sciencemag. tual endocasts of the tiatives and planning future actions—key org/cgi/content/ skulls of a micro- components of higher cognition. abstract/1109727), cephalic modern This enlarged area suggests that the little reveals that the hom- human, a modern Flores people may well have been capable inid apparently man- woman, a Homo of creating the stone tools that were found aged to pack a num- erectus, a pygmy, near them, which are more typical of those ber of features of and a chimpanzee, made by prehistoric modern humans than more advanced brains as well as latex earlier hominids including Homo erectus. into its very small endocasts of “The real take-home message here is that skull. Brain features other humans, pri- advanced behaviors, like making sophisti- preserved in its cranium cated stone tools, do not necessarily require suggest that the Flores Thinking ahead? The a large, modern, humanlike brain,” says hominid may have been able to highly convoluted frontal Spoor. “It can be done by reorganizing a perform advanced cognitive lobes of Homo floresiensis small brain, with convolutions and rewiring, tasks, says lead author Dean may indicate advanced and this goes to the heart of our understand- Falk of Florida State University in cognition. ing of human evolution.” L Tallahassee. That finding may overturn long-held ideas about the evolution of the human brain and also raises some provocative notions “Hobbit” Bones Go Home to Jakarta about how the Flores people evolved in the While scientists debate the evolutionary lessons to be drawn from the discovery of first place. “If they are correct, this is really Homo floresiensis (see main text), a bitter custody battle over the tiny hominid’s remains a stunner,” says anthropologist Leslie Aiello (Science, 25 February, p. 1179) may be almost over. Late last week, Indonesian paleo- of University College London (UCL). Evo- anthropologist Teuku Jacob gave most of the remains of up to eight individuals of the lutionary anatomist Fred Spoor, also of claimed new human species to members of the Center for Archaeology in Jakarta, the UCL, adds that the new study “upsets one of bones’ official repository. Jacob had been studying the bones since November, when a our main concepts of human evolution, that center researcher helped him pack them into a leather bag and take them to his labora- brain size has to increase for humans to tory at in the Indonesian city of Yogyakarta. become clever.” The work also undercuts Some members of the original Australian-Indonesian team that discovered the the notion proposed by some critics that the hominid on the island of Flores protested loudly that the hominid had been in effect kid- Flores bones are those of a microcephalic napped, in violation of a memorandum of understanding between the Australian and modern human rather than of a new species. Indonesian institutions involved. Jacob insisted that he had full permission from the To study the hominid’s brain, Falk and col- archaeological center and in turn charged the Australians with interfering with long- leagues, including anthropologist Charles standing arrangements among Indonesian laboratories. Hildebolt of the Mallinckrodt Institute of According to center director Tony Djubiantono, Jacob has now returned all the SCIENCE Radiology in St. Louis, Missouri, analyzed a hominid remains except two leg bones—a tibia and a femur—to Jakarta. Djubiantono , AL.

T E cast of the inner surface of its skull, or endo- says he is not sure when the rest of the bones will be reunited at their Jakarta home, but K L A F

cast, which preserves the surface features of says that he will call Jacob “next week and every week” until they are returned. . D the brain. Because the skull was too fragile for –M.B. :

the usual method of pouring liquid rubber CREDIT

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Not everyone is ready to Whatever the hominid’s capa- National University in Canberra counters discard the importance of bilities, the endocast results that the single European microcephalic brain size, however. argue against the notion that it analyzed “tells us virtually nothing about Anthropologist Katerina was a pathological case of the global range of microcephalic virtual Semendeferi of the Uni- microcephaly, the authors say. endocasts.” Others agree that the paper versity of California, San In overall brain shape, the Flo- alone does not completely rule out micro- Diego, who has studied res hominid least resembles the cephaly. “The case [against microcephaly] area 10 extensively, cautions microcephalic, and it also bears little is increasingly less likely but not entirely that “many would argue that resemblance to the pygmy. “The closed,” says Aiello. Spoor notes, however, absolute size is of paramount skull is totally the wrong shape” that few researchers are convinced by the importance”; she adds that to be a microcephalic, Falk says. microcephaly argument at this point. “Col- stronger evidence linking But anthropologist Alan leagues advocating that [the Flores the stone tools with the Thorne of the Australian hominid] is a modern human microcephalic small Flores people should start publishing hard evidence in would strengthen the No match. The brain of Homo floresiensis peer-reviewed journals to underpin their case for their cognitive (top) bears little resemblance in shape to that claims,” he says. abilities. of a modern human microcephalic. Assuming that Homo floresiensis is a L

PLANETARY SCIENCE A Strange Little Saturnian Ice Ball Gets Stranger Still When the Cassini spacecraft approached “cryovolcanic” eruptions. “You don’t see the Enceladus and has perhaps six times the mass, Saturn’s icy-bright satellite Enceladus flat, flooded picture of cryovolcanism” dis- yet it is covered by ancient cratered terrain. (en-SELL-uh-duss) last month, “we knew it cussed after Voyager, says Johnson. “Some- Unlike watery Europa, Enceladus does not was going to be weird,” says camera team thing flowed there, but it was very viscous.” All presently orbit in step with other moons, which member Torrence Johnson. “We just didn’t in all, large parts of Enceladus have know how weird.” The misfit satellite turned suffered “fairly energetic events out to be even stranger than scientists thought fairly recently,” perhaps less than in 1981, when Voyager 1 first visited. Voyager 100 million years ago. images showed the supposedly long-dead pri- The missing piece of the puzzle mordial ball of ice to have been geologically is an energy source that could have refreshed in recent times. Some unidentified warmed and melted ice as well as geologic process had smoothed its battered fueled tectonic forces on Ence- surface in places. Now, says Johnson, it ladus. Cassini may have found one. appears “some areas on Enceladus have to be As the spacecraft flew by, its radio very young, possibly younger than on Europa,” signal’s frequency shifted more the ice-covered ocean moon of Jupiter. than expected. That means the The Cassini camera, which returned 20 moon was gravitationally tugging times the fine detail of Voyager images, on Cassini harder than a ball of imaged three sorts of terrain as it swept within pure ice would, says camera team 1180 kilometers of Enceladus, says Johnson, member Joseph Veverka of Cornell who works at the Jet Propulsion Laboratory in University. “It’s definitely got some Pasadena, California. As seen in Voyager rock in there,” he says. And rock images, large parts of the 500-kilometer- would carry radioactive elements diameter moon are cratered by comet such as potassium-40 whose decay

JPL/NASA impacts, although the craters appear “soft- would have heated the interior, per- ened.” Presumably, this geologically older haps melted ice with the help of Wrinkled youth. Something has more than once crumpled SCIENCE; , surface ice has been warm enough to flow and some naturally occurring ammonia this part of icy Enceladus. Judging by the dearth of impact AL.

T E “relax.” A second sort of terrain that in Voy- antifreeze, and churned the interior craters, it happened in the geologically recent past. K L A F

. ager images looked completely blank now to deform the surface. D : )

M appears to be fractured by repeated squeezing Rock would help, notes planetary physicist could pump tidal energy to it from Saturn, O T T and stretching of a brittle crust. David Stevenson of the California Institute of although it might have done so in the past O B

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T A third terrain looks “scallopy, twisted, Technology in Pasadena, but, he adds, “I don’t (Science, 29 July 1983, p. 449). More clues to

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O taffylike,” says Johnson. Absent are the smooth understand why Enceladus is doing something Enceladus’s energetic lifestyle could come (T plains formed by once-fluid water that were different from other moons.” Neighboring next week (9 March), when Cassini makes an

CREDITS assumed to have spewed onto the surface in Tethys, for example, is twice the diameter of even closer pass. –RICHARD A. KERR

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