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South African fossils halfway between ape and human
visualisation by Erik Tollerud
IN BRIEF Gut drug halts cancer seizures
Multiple dwarf strikes gave the Milky Way its spirals A DWARF galaxy called Sagittarius can be credited with giving the Milky Way its signature spiral arms. Sagittarius struck our galaxy some 1.9 billion years ago. It then looped over the galactic “north pole” and struck again about 900 million years ago. It is heading back right now, on course for a third clash in 10 million years or so. Chris Purcell at the University of Pittsburgh, Pennsylvania, and colleagues used new mass estimates for Sagittarius to create the most accurate simulation yet of the effects of these impacts (see visualisation, above). The simulation starts with the Milky Way as a flat disc
with a central bar of stars and gas. After the first impact, instead of orbiting in circles around the central bar, some stars start orbiting in a variety of ellipses. These combine to form dense clumps of stars and gas in a spiral pattern. After the second impact, the spirals become remarkably similar to the ones seen in the Milky Way. At the same time, the central bar is preserved, just as in the actual Milky Way (Nature, DOI: 10.1038/nature10417). The impacts also generate ring-like structures around the Milky Way. One of these, says Purcell’s team, is very similar to a feature of the night sky known as the Monoceros ring. The simulation suggests that the ring connects to the spiral arms – beyond the view of older telescopes. Purcell predicts that the next generation of galactic maps will show the connection.
Glimpse of ape brain becoming human TWO years after its discovery in South Africa, a 2-million-year-old hominin species has revealed a hodgepodge of anatomical features that suggest it was halfway between our ape-like ancestors and more recent human-like kin. The ape-like australopithecines lived between 4 and 2 million years ago. Unlike apes, they walked on two legs, but they were
nothing special up top. Not until Homo erectus evolved, around 1.8 million years ago, did larger brains appear. Palaeontologists have spent a year intensively studying the two Australopithecus sediba skeletons found in South Africa, and say they may show how australopiths evolved into humans. A. sediba’s brain is particularly interesting. Kristian Carlson of the
University of the Witwatersrand in Johannesburg, South Africa, used synchrotron scans to build a detailed 3D image of the inside of one skull, allowing his team to calculate brain shape. Although the brain was small, Carlson says its orbitofrontal region, just behind the eyes, was a different shape to those of other australopiths and apes. It may have been rewired into a more human-like design (Science, DOI: 10.1126/science.1203922).
A DRUG for Crohn’s disease is proving adept at blocking seizures caused by brain tumours. Many people with brain cancers called gliomas experience epileptic-like seizures. Fits occur because the transport machinery that gliomas use to move an essential amino acid into the tumour also secretes glutamate, which causes surrounding neurons to fire uncontrollably. Harald Sontheimer’s team at the University of Alabama in Birmingham injected human glioma cells into 14 mice. Eight were given sulphasalazine, a drug which blocks the transport machinery; the rest a control. Sulphasalazine halved the number of fits (Nature Medicine, DOI: 10.1038/nm.2453). Since sulphasalazine is approved for treating Crohn’s disease, and well tolerated by patients, it could be used to treat glioma immediately, says Sontheimer.
Stellar crashes may forge gold WHERE did all the gold come from? Only hydrogen, helium and lithium were present after the big bang. Ordinary stars then fused elements up to the mass of iron. Anything heavier was created when smaller atoms captured neutrons, some of which then decayed into protons. A slow version of this process might occur in massive stars, but that could only account for about half of the remaining heavy elements. Rapid neutron capture is needed to explain the other half, including gold and lead. Mergers of neutron stars can do the trick, show new simulations led by Hans-Thomas Janka at the Max Planck Institute for Astrophysics in Garching, Germany (arxiv.org/ abs/1107.0899). 17 September 2011 | NewScientist | 19
IN BRIEF Gut drug halts cancer seizures
Multiple dwarf strikes gave the Milky Way its spirals A DWARF galaxy called Sagittarius can be credited with giving the Milky Way its signature spiral arms. Sagittarius struck our galaxy some 1.9 billion years ago. It then looped over the galactic “north pole” and struck again about 900 million years ago. It is heading back right now, on course for a third clash in 10 million years or so. Chris Purcell at the University of Pittsburgh, Pennsylvania, and colleagues used new mass estimates for Sagittarius to create the most accurate simulation yet of the effects of these impacts (see visualisation, above). The simulation starts with the Milky Way as a flat disc
with a central bar of stars and gas. After the first impact, instead of orbiting in circles around the central bar, some stars start orbiting in a variety of ellipses. These combine to form dense clumps of stars and gas in a spiral pattern. After the second impact, the spirals become remarkably similar to the ones seen in the Milky Way. At the same time, the central bar is preserved, just as in the actual Milky Way (Nature, DOI: 10.1038/nature10417). The impacts also generate ring-like structures around the Milky Way. One of these, says Purcell’s team, is very similar to a feature of the night sky known as the Monoceros ring. The simulation suggests that the ring connects to the spiral arms – beyond the view of older telescopes. Purcell predicts that the next generation of galactic maps will show the connection.
Glimpse of ape brain becoming human TWO years after its discovery in South Africa, a 2-million-year-old hominin species has revealed a hodgepodge of anatomical features that suggest it was halfway between our ape-like ancestors and more recent human-like kin. The ape-like australopithecines lived between 4 and 2 million years ago. Unlike apes, they walked on two legs, but they were
nothing special up top. Not until Homo erectus evolved, around 1.8 million years ago, did larger brains appear. Palaeontologists have spent a year intensively studying the two Australopithecus sediba skeletons found in South Africa, and say they may show how australopiths evolved into humans. A. sediba’s brain is particularly interesting. Kristian Carlson of the
University of the Witwatersrand in Johannesburg, South Africa, used synchrotron scans to build a detailed 3D image of the inside of one skull, allowing his team to calculate brain shape. Although the brain was small, Carlson says its orbitofrontal region, just behind the eyes, was a different shape to those of other australopiths and apes. It may have been rewired into a more human-like design (Science, DOI: 10.1126/science.1203922).
A DRUG for Crohn’s disease is proving adept at blocking seizures caused by brain tumours. Many people with brain cancers called gliomas experience epileptic-like seizures. Fits occur because the transport machinery that gliomas use to move an essential amino acid into the tumour also secretes glutamate, which causes surrounding neurons to fire uncontrollably. Harald Sontheimer’s team at the University of Alabama in Birmingham injected human glioma cells into 14 mice. Eight were given sulphasalazine, a drug which blocks the transport machinery; the rest a control. Sulphasalazine halved the number of fits (Nature Medicine, DOI: 10.1038/nm.2453). Since sulphasalazine is approved for treating Crohn’s disease, and well tolerated by patients, it could be used to treat glioma immediately, says Sontheimer.
Stellar crashes may forge gold WHERE did all the gold come from? Only hydrogen, helium and lithium were present after the big bang. Ordinary stars then fused elements up to the mass of iron. Anything heavier was created when smaller atoms captured neutrons, some of which then decayed into protons. A slow version of this process might occur in massive stars, but that could only account for about half of the remaining heavy elements. Rapid neutron capture is needed to explain the other half, including gold and lead. Mergers of neutron stars can do the trick, show new simulations led by Hans-Thomas Janka at the Max Planck Institute for Astrophysics in Garching, Germany (arxiv.org/ abs/1107.0899). 17 September 2011 | NewScientist | 19