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Frequent hurricanes decimate sea turtle beaches
DANIEL DAY/STONE +
THAT office job might be raising your blood pressure in more ways than one. A link between the muscles in the neck, blood pressure and heart rate has long been suspected. Now Jim Deuchars and colleagues at the University of Leeds, UK, have found a direct neural connection between these neck muscles and a part of the brainstem – called the nucleus tractus solitarius (NTS) – which plays a crucial role in regulating heart rate and blood pressure. Deuchars’s team was using mice to investigate how the brain responds to a variety of stimulatory and inhibitory proteins. They noticed that a group of brain cells connected to the neck muscles kept firing in response to both types of proteins, suggesting the cells played a very active role in the brain. “The cells lit up time and time again, so we looked at what they were doing,” says team member Ian Edwards. It turned out that these cells are also connected to the NTS (The Journal of Neuroscience, DOI: 10.1523/jneurosci.0638-07.2007). Edwards says the finding could explain why blood pressure and heart rate sometimes change when the neck muscles are injured – through whiplash, for example. Similarly, it is possible that hours spent hunched over a computer may raise blood pressure. “The pathway exists for bad posture to really have an effect,” Edwards says.
www.newscientist.com
Why children’s chattering is inevitable YOUNG children become chatterboxes within months of speaking just the occasional word. Now one scientist thinks he knows why. Parents of small children will be familiar with the so-called “word spurt”, when a child goes from barely talking to suddenly uttering hundreds of new words, sometimes after hearing them only once. Various theories have been suggested to explain this phenomenon. For instance, perhaps learning a few basic words helps a child learn others,
or maybe children quickly understand that if there is a word they don’t recognise, it belongs to the object they can’t name. Now language psychologist Bob McMurray at the University of Iowa in Iowa City has a simpler explanation. He believes that the acceleration in a child’s learning is down to the way most languages are structured. All languages, he says, contain a distribution of words where most are of medium difficulty and a few are either very easy or very difficult. Children learn all words in parallel,
McMurray adds. He factored these rules into a computer model that simulated how long it would take to learn 10,000 new words. Each simulation produced the same pattern: essentially, a child masters the small number of easy words, but has simultaneously been working on the medium difficulty words. Soon afterwards they master these as well, but it feels like a burst because there are more of them. “Acceleration is an unavoidable by-product of variation in difficulty,” says McMurray (Science, vol 317, p 631). MARK CONLIN/ALAMY
Blood pressure’s a pain in the neck
Females turned into macho males HOW do you turn a sexually passive female mouse into a masculine sex machine? Remove her vomeronasal organ. Sitting in the nasal cavity, the VNO detects pheromones, which carry social and sexual signals. A team led by Catherine Dulac at Harvard University either surgically removed the organ in adult female mice, or studied females in which both copies of the gene for a key signalling protein in the organ had been knocked out. In both groups, the females indiscriminately pursued and mounted mice of either sex. They also adopted the pelvic thrusts and ultrasonic mating calls typical of sexually mature male mice (Nature, DOI: 10.1038/ nature06089). Dulac says this suggests that the brains of male and female mice are not necessarily hardwired differently, at least when it comes to mating behaviours. “It really contradicts a lot of the central dogma about sex-specific behaviour,” she says. However, human sexual behaviour is unlikely to be so simply determined – anatomists disagree over whether we even posses a VNO.
Tropical storms are killing turtles INCREASINGLY frequent and ferocious hurricanes, fuelled by warming oceans, could pose a threat to sea turtles by destroying their nests. Kyle Van Houtan of Emory University in Atlanta, Georgia, analysed survey data collected over a decade from sea turtle nests on the beaches of Dry Tortugas National Park, an island chain off the Florida coast. During that time, tropical storm surges frequently destroyed turtle nests by ejecting eggs from the sand or drenching them in salt water. Nest destruction by storms seems to be getting more frequent. Between
1995 and 2004, the proportion of surviving nests dropped by more than half. In 2004, the final year of the survey, a series of category 3, 4 and 5 storms destroyed three-quarters of loggerhead and green turtle nests (Current Biology, DOI: 10.1016/j. cub.2007.06.021). Another study, performed by David Pike of the University of Sydney in Australia, suggests that storms arriving early in the season are especially deadly to turtle clutches. During seasons in which the first storm arrived before 20 August, at least 95 per cent of green sea turtle nests at Canaveral National Seashore in Florida were destroyed before the eggs hatched (Canadian Journal of Zoology, vol 85, p 737).
11 August 2007 | NewScientist | 17
THAT office job might be raising your blood pressure in more ways than one. A link between the muscles in the neck, blood pressure and heart rate has long been suspected. Now Jim Deuchars and colleagues at the University of Leeds, UK, have found a direct neural connection between these neck muscles and a part of the brainstem – called the nucleus tractus solitarius (NTS) – which plays a crucial role in regulating heart rate and blood pressure. Deuchars’s team was using mice to investigate how the brain responds to a variety of stimulatory and inhibitory proteins. They noticed that a group of brain cells connected to the neck muscles kept firing in response to both types of proteins, suggesting the cells played a very active role in the brain. “The cells lit up time and time again, so we looked at what they were doing,” says team member Ian Edwards. It turned out that these cells are also connected to the NTS (The Journal of Neuroscience, DOI: 10.1523/jneurosci.0638-07.2007). Edwards says the finding could explain why blood pressure and heart rate sometimes change when the neck muscles are injured – through whiplash, for example. Similarly, it is possible that hours spent hunched over a computer may raise blood pressure. “The pathway exists for bad posture to really have an effect,” Edwards says.
www.newscientist.com
Why children’s chattering is inevitable YOUNG children become chatterboxes within months of speaking just the occasional word. Now one scientist thinks he knows why. Parents of small children will be familiar with the so-called “word spurt”, when a child goes from barely talking to suddenly uttering hundreds of new words, sometimes after hearing them only once. Various theories have been suggested to explain this phenomenon. For instance, perhaps learning a few basic words helps a child learn others,
or maybe children quickly understand that if there is a word they don’t recognise, it belongs to the object they can’t name. Now language psychologist Bob McMurray at the University of Iowa in Iowa City has a simpler explanation. He believes that the acceleration in a child’s learning is down to the way most languages are structured. All languages, he says, contain a distribution of words where most are of medium difficulty and a few are either very easy or very difficult. Children learn all words in parallel,
McMurray adds. He factored these rules into a computer model that simulated how long it would take to learn 10,000 new words. Each simulation produced the same pattern: essentially, a child masters the small number of easy words, but has simultaneously been working on the medium difficulty words. Soon afterwards they master these as well, but it feels like a burst because there are more of them. “Acceleration is an unavoidable by-product of variation in difficulty,” says McMurray (Science, vol 317, p 631). MARK CONLIN/ALAMY
Blood pressure’s a pain in the neck
Females turned into macho males HOW do you turn a sexually passive female mouse into a masculine sex machine? Remove her vomeronasal organ. Sitting in the nasal cavity, the VNO detects pheromones, which carry social and sexual signals. A team led by Catherine Dulac at Harvard University either surgically removed the organ in adult female mice, or studied females in which both copies of the gene for a key signalling protein in the organ had been knocked out. In both groups, the females indiscriminately pursued and mounted mice of either sex. They also adopted the pelvic thrusts and ultrasonic mating calls typical of sexually mature male mice (Nature, DOI: 10.1038/ nature06089). Dulac says this suggests that the brains of male and female mice are not necessarily hardwired differently, at least when it comes to mating behaviours. “It really contradicts a lot of the central dogma about sex-specific behaviour,” she says. However, human sexual behaviour is unlikely to be so simply determined – anatomists disagree over whether we even posses a VNO.
Tropical storms are killing turtles INCREASINGLY frequent and ferocious hurricanes, fuelled by warming oceans, could pose a threat to sea turtles by destroying their nests. Kyle Van Houtan of Emory University in Atlanta, Georgia, analysed survey data collected over a decade from sea turtle nests on the beaches of Dry Tortugas National Park, an island chain off the Florida coast. During that time, tropical storm surges frequently destroyed turtle nests by ejecting eggs from the sand or drenching them in salt water. Nest destruction by storms seems to be getting more frequent. Between
1995 and 2004, the proportion of surviving nests dropped by more than half. In 2004, the final year of the survey, a series of category 3, 4 and 5 storms destroyed three-quarters of loggerhead and green turtle nests (Current Biology, DOI: 10.1016/j. cub.2007.06.021). Another study, performed by David Pike of the University of Sydney in Australia, suggests that storms arriving early in the season are especially deadly to turtle clutches. During seasons in which the first storm arrived before 20 August, at least 95 per cent of green sea turtle nests at Canaveral National Seashore in Florida were destroyed before the eggs hatched (Canadian Journal of Zoology, vol 85, p 737).
11 August 2007 | NewScientist | 17