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Massacre find is one of oldest wars
in Brief
Marta Mirazon Lahr & Fabio Lahr
WAR? ‘Twas ever thus. Remains of a grisly massacre discovered in Nataruk, Kenya, show that violent conflict was a fact of life even for our hunter-gatherer ancestors. Ten skeletons excavated at the site show signs of a violent death, including blows and cuts to the head. Two of them have obsidian projectile tips embedded in the body, probably from arrows. The body positions of another two suggest that their hands might have been tied when they died (Nature, DOI: 10.1038/nature16477). The site, dated to around 10,000 years ago, is the only known evidence of a prehistoric massacre of hunter-gatherer people, says Marta Mirazón Lahr at the University of Cambridge, whose team analysed the skeletons. “It was an intentional conflict between two groups, and it involved a large number of people, so it qualifies in my mind as small-scale warfare,” she says. The motivation for the attack could have been a raid for resources, such as territory or fish in the nearby lake, the team suggests. Or aggression might have been a standard response when groups of humans met each other, as it is for chimpanzees. “It could be that two groups met, they were both foraging parties, and one of them was carrying weapons and they attacked,” says Mirazón Lahr.
18 | NewScientist | 23 January 2016
Distant quasars can suddenly flicker into life MOST cosmic events happen on huge timescales. Not so for quasars – the bright centres of galaxies that are powered by supermassive black holes gobbling down gas and dust. We have just seen them ignite in a matter of years. Astronomers expect quasars to use up their fuel and settle down into quiet galaxies – a process that should take hundreds of thousands of years. So last year, when a dozen quasars were spotted shutting down in just hundreds of days, it was a shock.
Chelsea MacLeod of the University of Edinburgh, UK, and her colleagues wondered if these objects might turn on again. The team compared images of galaxies from the Sloan Digital Sky Survey with images of the same galaxies from the PanSTARRS survey, taken 10 years later. They found five galaxies that appeared to shape-shift into quasars, one of which had earlier shut down (arxiv.org/ abs/1509.08393). It’s not clear if these other four quasars are turning on for the first
time, or if they are also flickering. But astronomers used to think it would take thousands to millions of years to funnel enough gas on to a supermassive black hole to spawn a quasar. “This is a bit of an embarrassing moment for black hole and quasar scientists,” says Eric Morganson of Harvard University. So now the big question is how these beasts ignite in the first place. Common explanations involving unstable galaxies or galaxy mergers can’t explain the speedy switch-on. Heikka Valja
Massacre find is one of oldest wars
For new stories every day, visit newscientist.com/news
Mammoth spawns migration rethink IT’S a trope of life in the ice age: a giant mammoth brought down by a hunting party’s spears. But such a scene can also provide evidence of the migration of our ancestors. Now, the discovery of a butchered mammoth carcass in north-west Siberia suggests humans were living in the Arctic 10,000 years earlier than we thought. The 45,000-year-old find, along with that of a similarly ancient wolf bone bearing signs of arrow damage in eastern Siberia, suggests humans had colonised the region by this time. If so, this could reset our picture of when people first reached the Americas from Asia, assumed to be around 20,000 years ago. They may have had the chance to move east into North America earlier, says Vladimir Pitulko at the Russian Academy of Sciences in St Petersburg, leader of the team that studied the remains (Science, doi.org/bbvr). The ice age was at its height 20,000 years ago, and the Bering Strait between Siberia and Alaska would have been a land bridge. An earlier migration is not impossible because the land bridge probably existed earlier, says Pitulko.
How to tie a knot in quantum gas QUANTUM matter is getting tied up in knots - in a good way. It could lead to new theories about the particles that make up our universe. Mikko Möttönen of Aalto University in Finland and his colleagues have tied up a type of quantum matter called a BoseEinstein condensate (BEC). BECs are an unusual kind of gas in which the atoms have been cooled to near absolute zero, putting them all into a single quantum state. Using a changing magnetic field, Möttönen’s team coaxed a BEC made from rubidium atoms into a complex knot
called a Hopf fibration, a tangle of interlocking circles in the shape of a doughnut (Nature Physics, DOI: 10.1038/nphys3624). “These knots are inspiring and visually rich,” Möttönen says. “After having worked with them, you start to really appreciate their elegance.” The knots aren’t just pretty. Topological quantum field theories hold that particles are described by mathematical shapes similar to knots within quantum fields that fill the universe. Creating real quantum knots could help develop such theories, says Möttönen.
Marta Mirazon Lahr & Fabio Lahr
WAR? ‘Twas ever thus. Remains of a grisly massacre discovered in Nataruk, Kenya, show that violent conflict was a fact of life even for our hunter-gatherer ancestors. Ten skeletons excavated at the site show signs of a violent death, including blows and cuts to the head. Two of them have obsidian projectile tips embedded in the body, probably from arrows. The body positions of another two suggest that their hands might have been tied when they died (Nature, DOI: 10.1038/nature16477). The site, dated to around 10,000 years ago, is the only known evidence of a prehistoric massacre of hunter-gatherer people, says Marta Mirazón Lahr at the University of Cambridge, whose team analysed the skeletons. “It was an intentional conflict between two groups, and it involved a large number of people, so it qualifies in my mind as small-scale warfare,” she says. The motivation for the attack could have been a raid for resources, such as territory or fish in the nearby lake, the team suggests. Or aggression might have been a standard response when groups of humans met each other, as it is for chimpanzees. “It could be that two groups met, they were both foraging parties, and one of them was carrying weapons and they attacked,” says Mirazón Lahr.
18 | NewScientist | 23 January 2016
Distant quasars can suddenly flicker into life MOST cosmic events happen on huge timescales. Not so for quasars – the bright centres of galaxies that are powered by supermassive black holes gobbling down gas and dust. We have just seen them ignite in a matter of years. Astronomers expect quasars to use up their fuel and settle down into quiet galaxies – a process that should take hundreds of thousands of years. So last year, when a dozen quasars were spotted shutting down in just hundreds of days, it was a shock.
Chelsea MacLeod of the University of Edinburgh, UK, and her colleagues wondered if these objects might turn on again. The team compared images of galaxies from the Sloan Digital Sky Survey with images of the same galaxies from the PanSTARRS survey, taken 10 years later. They found five galaxies that appeared to shape-shift into quasars, one of which had earlier shut down (arxiv.org/ abs/1509.08393). It’s not clear if these other four quasars are turning on for the first
time, or if they are also flickering. But astronomers used to think it would take thousands to millions of years to funnel enough gas on to a supermassive black hole to spawn a quasar. “This is a bit of an embarrassing moment for black hole and quasar scientists,” says Eric Morganson of Harvard University. So now the big question is how these beasts ignite in the first place. Common explanations involving unstable galaxies or galaxy mergers can’t explain the speedy switch-on. Heikka Valja
Massacre find is one of oldest wars
For new stories every day, visit newscientist.com/news
Mammoth spawns migration rethink IT’S a trope of life in the ice age: a giant mammoth brought down by a hunting party’s spears. But such a scene can also provide evidence of the migration of our ancestors. Now, the discovery of a butchered mammoth carcass in north-west Siberia suggests humans were living in the Arctic 10,000 years earlier than we thought. The 45,000-year-old find, along with that of a similarly ancient wolf bone bearing signs of arrow damage in eastern Siberia, suggests humans had colonised the region by this time. If so, this could reset our picture of when people first reached the Americas from Asia, assumed to be around 20,000 years ago. They may have had the chance to move east into North America earlier, says Vladimir Pitulko at the Russian Academy of Sciences in St Petersburg, leader of the team that studied the remains (Science, doi.org/bbvr). The ice age was at its height 20,000 years ago, and the Bering Strait between Siberia and Alaska would have been a land bridge. An earlier migration is not impossible because the land bridge probably existed earlier, says Pitulko.
How to tie a knot in quantum gas QUANTUM matter is getting tied up in knots - in a good way. It could lead to new theories about the particles that make up our universe. Mikko Möttönen of Aalto University in Finland and his colleagues have tied up a type of quantum matter called a BoseEinstein condensate (BEC). BECs are an unusual kind of gas in which the atoms have been cooled to near absolute zero, putting them all into a single quantum state. Using a changing magnetic field, Möttönen’s team coaxed a BEC made from rubidium atoms into a complex knot
called a Hopf fibration, a tangle of interlocking circles in the shape of a doughnut (Nature Physics, DOI: 10.1038/nphys3624). “These knots are inspiring and visually rich,” Möttönen says. “After having worked with them, you start to really appreciate their elegance.” The knots aren’t just pretty. Topological quantum field theories hold that particles are described by mathematical shapes similar to knots within quantum fields that fill the universe. Creating real quantum knots could help develop such theories, says Möttönen.