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Chimps stay stuck in an innovative rut
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CLIMATE change isn’t always bad news – for the Incas, it may have fuelled the growth of an empire. Sediments from a core going back 4000 years have revealed a surge in Inca land use and agriculture around 1100. The sediments, which contain evidence of Inca farming including the remains of seeds and mites that feed on llama dung, come from Marcacocha, a small lake near Cuzco, Peru, at the heart of the ancient empire. Lead researcher Alex ChepstowLusty of Montpellier 2 University in France says warmer temperatures enabled the Inca to build mountainside terraces for growing crops at altitudes previously too cold to support agriculture, and provided meltwater from the Andean glaciers for irrigation (Climate of the Past, vol 5, p 375). He says data from a nearby ice core confirms that temperatures rose in the region around 1100. Later, centuries of abundant harvests from the terraces would have freed people for other tasks, such as building extensive road networks. Most importantly, it enabled the creation of an army which swept all before it from about 1400 until defeat by the Spanish in 1533. “All this would have been impossible without the increase in temperature,” Chepstow-Lusty argues.
Comets wreaked icy devastation on early Earth DID comets made mainly of water ice launch an assault on the young Earth and its fledgling moon? The two worlds were battered by debris about 3.85 billion years ago, during the so-called Late Heavy Bombardment (LHB), but it is unclear whether rocky asteroids or icy comets were the key culprits. Uffe Gråe Jørgensen at the Niels Bohr Institute in Copenhagen, Denmark, and colleagues reasoned that the element iridium could provide a clue. Comets and asteroids both contain iridium, but comets would leave less
iridium on the Earth and hardly any on the moon, compared with asteroids, says Jørgensen. That’s because the higher speed of comets and the high volatility of their constituents would create giant plumes on impact, so more of the iridium would escape into space, compared with impacts by rocky asteroids. If comets were to blame, the team calculated, we would expect to see iridium levels of roughly 130 parts per trillion in ancient terrestrial rocks. Sure enough, they measured 150 parts per
trillion in 3.8-billion-year-old rocks from Greenland. The calculations also predicted lunar rocks should have iridium levels of 10 parts per trillion or less – a figure that moon rocks returned by NASA’s Apollo missions have already confirmed (Icarus, DOI: 10.1016/j.icarus.2009.07.015). The team calculates that if most of the impacts during the LHB came from comets, about 3400 tonnes of ice would have hit each square metre of the Earth. That roughly tallies with the amount of water in Earth’s oceans today. CYRIL RUOSO/MINDEN PICTURES/FLPA
Inca thrived as climate warmed
That place reminds me of cocaine SIGHTS and smells that remind addicts of a previous high can induce strong cravings and make quitting tough. Now the neurons responsible for these “association memories” have been deactivated in rats. Bruce Hope and colleagues at the National Institute on Drug Abuse in Baltimore, Maryland, studied rats engineered so that their neurons released a specific enzyme whenever they produced a protein called Fos, which only happens when neurons are highly activated. This allowed them to shut down Fos-producing neurons, by adding a drug that works only when the enzyme is present. When the researchers trained addicted rats to associate a particular setting with cocaine, certain neurons became highly activated and produced Fos. The researchers then shut down the neurons, and this seemed to erase the association (Nature Neuroscience, DOI: 10.1038/ nn.2364). They conclude that they had successfully deactivated the neurons involved in association. Hope is now looking for similar molecules in humans to provide the basis for investigating such associations in people.
Chimps stay stuck in an innovative rut FOR all their cognitive prowess, chimps will never create steam engines, stone pyramids, or even a simple wheel. That’s because they can’t latch onto new ways of doing things, says Andrew Whiten, a psychologist at the University of St Andrews, UK. Along with his colleagues, Whiten devised a simple test to show that unlike children, who instinctively adopt better methods for obtaining a reward, chimps will stick to their tried and tested techniques. The researchers taught 11 young chimps to scoop out honey from
inside a box by dipping a stick into a hole in the box. They then showed them how moving the stick in the hole released a latch that opened the box, offering up all the honey plus hidden peanuts. Most 3 and 4-year old children readily adopted the better solution, but none of the apes did (Philosophical Transactions of the Royal Society B, vol 364, p 2417). “They didn’t get it. They didn’t show any kind of cumulative cultural evolution,” Whiten says. “There’s something curious going on in these non-human species, where they get stuck on simpler techniques.”
1 August 2009 | NewScientist | 15
F1 ONLINE/REX FEATURES
CLIMATE change isn’t always bad news – for the Incas, it may have fuelled the growth of an empire. Sediments from a core going back 4000 years have revealed a surge in Inca land use and agriculture around 1100. The sediments, which contain evidence of Inca farming including the remains of seeds and mites that feed on llama dung, come from Marcacocha, a small lake near Cuzco, Peru, at the heart of the ancient empire. Lead researcher Alex ChepstowLusty of Montpellier 2 University in France says warmer temperatures enabled the Inca to build mountainside terraces for growing crops at altitudes previously too cold to support agriculture, and provided meltwater from the Andean glaciers for irrigation (Climate of the Past, vol 5, p 375). He says data from a nearby ice core confirms that temperatures rose in the region around 1100. Later, centuries of abundant harvests from the terraces would have freed people for other tasks, such as building extensive road networks. Most importantly, it enabled the creation of an army which swept all before it from about 1400 until defeat by the Spanish in 1533. “All this would have been impossible without the increase in temperature,” Chepstow-Lusty argues.
Comets wreaked icy devastation on early Earth DID comets made mainly of water ice launch an assault on the young Earth and its fledgling moon? The two worlds were battered by debris about 3.85 billion years ago, during the so-called Late Heavy Bombardment (LHB), but it is unclear whether rocky asteroids or icy comets were the key culprits. Uffe Gråe Jørgensen at the Niels Bohr Institute in Copenhagen, Denmark, and colleagues reasoned that the element iridium could provide a clue. Comets and asteroids both contain iridium, but comets would leave less
iridium on the Earth and hardly any on the moon, compared with asteroids, says Jørgensen. That’s because the higher speed of comets and the high volatility of their constituents would create giant plumes on impact, so more of the iridium would escape into space, compared with impacts by rocky asteroids. If comets were to blame, the team calculated, we would expect to see iridium levels of roughly 130 parts per trillion in ancient terrestrial rocks. Sure enough, they measured 150 parts per
trillion in 3.8-billion-year-old rocks from Greenland. The calculations also predicted lunar rocks should have iridium levels of 10 parts per trillion or less – a figure that moon rocks returned by NASA’s Apollo missions have already confirmed (Icarus, DOI: 10.1016/j.icarus.2009.07.015). The team calculates that if most of the impacts during the LHB came from comets, about 3400 tonnes of ice would have hit each square metre of the Earth. That roughly tallies with the amount of water in Earth’s oceans today. CYRIL RUOSO/MINDEN PICTURES/FLPA
Inca thrived as climate warmed
That place reminds me of cocaine SIGHTS and smells that remind addicts of a previous high can induce strong cravings and make quitting tough. Now the neurons responsible for these “association memories” have been deactivated in rats. Bruce Hope and colleagues at the National Institute on Drug Abuse in Baltimore, Maryland, studied rats engineered so that their neurons released a specific enzyme whenever they produced a protein called Fos, which only happens when neurons are highly activated. This allowed them to shut down Fos-producing neurons, by adding a drug that works only when the enzyme is present. When the researchers trained addicted rats to associate a particular setting with cocaine, certain neurons became highly activated and produced Fos. The researchers then shut down the neurons, and this seemed to erase the association (Nature Neuroscience, DOI: 10.1038/ nn.2364). They conclude that they had successfully deactivated the neurons involved in association. Hope is now looking for similar molecules in humans to provide the basis for investigating such associations in people.
Chimps stay stuck in an innovative rut FOR all their cognitive prowess, chimps will never create steam engines, stone pyramids, or even a simple wheel. That’s because they can’t latch onto new ways of doing things, says Andrew Whiten, a psychologist at the University of St Andrews, UK. Along with his colleagues, Whiten devised a simple test to show that unlike children, who instinctively adopt better methods for obtaining a reward, chimps will stick to their tried and tested techniques. The researchers taught 11 young chimps to scoop out honey from
inside a box by dipping a stick into a hole in the box. They then showed them how moving the stick in the hole released a latch that opened the box, offering up all the honey plus hidden peanuts. Most 3 and 4-year old children readily adopted the better solution, but none of the apes did (Philosophical Transactions of the Royal Society B, vol 364, p 2417). “They didn’t get it. They didn’t show any kind of cumulative cultural evolution,” Whiten says. “There’s something curious going on in these non-human species, where they get stuck on simpler techniques.”
1 August 2009 | NewScientist | 15