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Long-lost lake may have helped humans out of Africa
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Lost lake was a pit stop on our migration out of Africa
Quantum chip flunks landmark speed test THE quantum revolution is still in the slow lane. The first head-to-head speed test of the D-Wave Two, the commercial quantum computer recently purchased by Google, suggests that the machine performs no better than an ordinary PC. In theory, quantum computers are capable of calculating answers to problems much faster than standard PCs. Instead of storing information in
were exposed, and so when the lake began to shrink. This was a key time for humans, who appear in the fossil record in Ethiopia 200,000 years ago. By 100,000 years ago they reached the eastern Mediterranean. David Haberlah
A GIANT, long-vanished lake along the White Nile may have been a vital way station for early humans leaving Africa. The 45,000-squarekilometre lake would be one of the world’s largest lakes if it existed today, and it was in the right place at the right time for at least one of two key migrations. One took people to what is now Israel 100,000 years ago, and another peopled Eurasia 70,000 years ago. Geologists had seen traces of an ancient lake in the arid region south of Khartoum in Sudan, but did not know when it dried up. So Martin Williams of the University of Adelaide in Australia and Tim Barrows of the University of Exeter, UK, collected samples from former lake-shore deposits, and dated them to about 109,000 years ago. They traced the lost lake along 650 kilometres of the White Nile, one of two main tributaries to the Nile. At points, the lake was almost 80 kilometres wide (Geology, doi.org/q2k). Its peak extent came in a warm period before the last ice age. Barrows says it did not stay this large for long – the deposits formed in a few thousand years. His dating methods reveal how long it has been since the deposits
bits as either 0s or 1s, quantum machines use quantum bits, or qubits, that can be both 0 and 1 at the same time. So far, however, the quantum devices built in labs can only support a handful of qubits, which limits their speed. The computers built by commercial firm D-Wave of Burnaby in British Columbia, Canada, have many more qubits – about 500 – but use a method known as adiabatic quantum computing, which, unlike the traditional method, has not yet been proved to give a quantum power boost. Nevertheless, Google splashed out on a D-Wave Two machine last
But DNA shows that the ancestors of modern Eurasians left Africa later, about 71,000 years ago, says Stephen Oppenheimer of the University of Oxford. He thinks this later migration crossed the mouth of the Red Sea, when the ice age had lowered sea levels by 100 metres. “A big lake like this would have been a great place to live,” he says. “It would have supported a large population, probably
fishing and hunting game.” The lake was shallow and its size would have varied with the seasons. But that wouldn’t have stopped people using it. “Even in arid times, these lake margins would have retained some stability,” says Laura Basell of Queen’s University Belfast, UK. So far there is no way to confirm that humans lived in the area, because the current conflict in the region means it is too dangerous to return for further excavations. Nevertheless, anthropologists think it was inhabited. However, as climate changed and the monsoon rains dwindled, the lake shrank. Its disappearance would have been a disaster for people in the area, forcing them to move elsewhere, says Ofer BarYosef of Harvard University. Migrants could have followed the Nile to the Mediterranean, and then east to Israel. So the lake’s disappearance may explain the first migration out of Africa. The lake may also have helped the later migration that peopled Eurasia, but this is less clear. It depends when it finally vanished. Barrow’s analysis only shows when the lake began shrinking. If the lake endured 70,000 years ago, it may have launched the second migration. Barrow, however, is sceptical. He says the lake “would have been long gone –So long, and thanks for all the fish– by 70,000 years ago”. Jeff Hecht n
year. It is housed at a NASA research centre. The company has so far used it to design blink-detection algorithms for its upcoming Glass headset and NASA is exploring its potential for finding exoplanets. Now a team led by Matthias Troyer of ETH Zurich in Switzerland has tested a D-Wave Two computer against a conventional machine running an optimised algorithm – and found no evidence of superior
“Critics say that Google’s D-Wave computer is simply not exploiting quantum mechanics”
performance in the quantum device. Critics say the D-Wave computer is not exploiting quantum mechanics to calculate faster than a regular PC. But the latest test only looked at one specific type of problem, and Google is hopeful that the D-Wave Two will work faster in other areas. D-Wave is also scheduled to release a new version of its quantum chip with 1000 qubits later this year. The company thinks that will improve benchmark results. “We haven’t yet seen any fundamental limits to performance that can’t be improved with design changes,” says Jeremy Hilton of D-Wave. Jacob Aron n 25 January 2014 | NewScientist | 11
Lost lake was a pit stop on our migration out of Africa
Quantum chip flunks landmark speed test THE quantum revolution is still in the slow lane. The first head-to-head speed test of the D-Wave Two, the commercial quantum computer recently purchased by Google, suggests that the machine performs no better than an ordinary PC. In theory, quantum computers are capable of calculating answers to problems much faster than standard PCs. Instead of storing information in
were exposed, and so when the lake began to shrink. This was a key time for humans, who appear in the fossil record in Ethiopia 200,000 years ago. By 100,000 years ago they reached the eastern Mediterranean. David Haberlah
A GIANT, long-vanished lake along the White Nile may have been a vital way station for early humans leaving Africa. The 45,000-squarekilometre lake would be one of the world’s largest lakes if it existed today, and it was in the right place at the right time for at least one of two key migrations. One took people to what is now Israel 100,000 years ago, and another peopled Eurasia 70,000 years ago. Geologists had seen traces of an ancient lake in the arid region south of Khartoum in Sudan, but did not know when it dried up. So Martin Williams of the University of Adelaide in Australia and Tim Barrows of the University of Exeter, UK, collected samples from former lake-shore deposits, and dated them to about 109,000 years ago. They traced the lost lake along 650 kilometres of the White Nile, one of two main tributaries to the Nile. At points, the lake was almost 80 kilometres wide (Geology, doi.org/q2k). Its peak extent came in a warm period before the last ice age. Barrows says it did not stay this large for long – the deposits formed in a few thousand years. His dating methods reveal how long it has been since the deposits
bits as either 0s or 1s, quantum machines use quantum bits, or qubits, that can be both 0 and 1 at the same time. So far, however, the quantum devices built in labs can only support a handful of qubits, which limits their speed. The computers built by commercial firm D-Wave of Burnaby in British Columbia, Canada, have many more qubits – about 500 – but use a method known as adiabatic quantum computing, which, unlike the traditional method, has not yet been proved to give a quantum power boost. Nevertheless, Google splashed out on a D-Wave Two machine last
But DNA shows that the ancestors of modern Eurasians left Africa later, about 71,000 years ago, says Stephen Oppenheimer of the University of Oxford. He thinks this later migration crossed the mouth of the Red Sea, when the ice age had lowered sea levels by 100 metres. “A big lake like this would have been a great place to live,” he says. “It would have supported a large population, probably
fishing and hunting game.” The lake was shallow and its size would have varied with the seasons. But that wouldn’t have stopped people using it. “Even in arid times, these lake margins would have retained some stability,” says Laura Basell of Queen’s University Belfast, UK. So far there is no way to confirm that humans lived in the area, because the current conflict in the region means it is too dangerous to return for further excavations. Nevertheless, anthropologists think it was inhabited. However, as climate changed and the monsoon rains dwindled, the lake shrank. Its disappearance would have been a disaster for people in the area, forcing them to move elsewhere, says Ofer BarYosef of Harvard University. Migrants could have followed the Nile to the Mediterranean, and then east to Israel. So the lake’s disappearance may explain the first migration out of Africa. The lake may also have helped the later migration that peopled Eurasia, but this is less clear. It depends when it finally vanished. Barrow’s analysis only shows when the lake began shrinking. If the lake endured 70,000 years ago, it may have launched the second migration. Barrow, however, is sceptical. He says the lake “would have been long gone –So long, and thanks for all the fish– by 70,000 years ago”. Jeff Hecht n
year. It is housed at a NASA research centre. The company has so far used it to design blink-detection algorithms for its upcoming Glass headset and NASA is exploring its potential for finding exoplanets. Now a team led by Matthias Troyer of ETH Zurich in Switzerland has tested a D-Wave Two computer against a conventional machine running an optimised algorithm – and found no evidence of superior
“Critics say that Google’s D-Wave computer is simply not exploiting quantum mechanics”
performance in the quantum device. Critics say the D-Wave computer is not exploiting quantum mechanics to calculate faster than a regular PC. But the latest test only looked at one specific type of problem, and Google is hopeful that the D-Wave Two will work faster in other areas. D-Wave is also scheduled to release a new version of its quantum chip with 1000 qubits later this year. The company thinks that will improve benchmark results. “We haven’t yet seen any fundamental limits to performance that can’t be improved with design changes,” says Jeremy Hilton of D-Wave. Jacob Aron n 25 January 2014 | NewScientist | 11