Unlocking mysteries in the sun’s 11-year cycle
News and notes about science
Our sun may be special to us, but among all the stars in the galaxy, it’s not that unique.
According to a study published July 13 in the journal Science, our beloved star can be classified as an ordinary “solartype” star, meaning that the internal processes that control its activity are similar to those seen in many other nearby stars.
The sun goes through an 11-year cycle where its magnetic poles flip — imagine the north and south poles on Earth changing place — and during this time the sun’s activity changes between subdued and tumultuous. When activity is low, it is known as solar minimum, and when activity is high, it is known as solar maximum.
As the sun nears solar maximum and its activity cycle ramps up, its surface gets covered in sunspots, which are ephemeral dark marks created by strong magnetic activity.
“Above sunspots you have complex structures that trigger dynamic phenomenons, eruptions that are like volcanoes,” said Antoine Strugarek, a solar physicist at the French Alternative Energies and Atomic Energy Commission and at the University of Montreal. “Those eruptions can impact our Earth.”
The sun’s emissions can interact with satellites and even influence power grids on Earth, according to Strugarek. So to better predict the sun’s activity, scientists need to better understand the 11-year cycle and how it generates magnetic fields.
Living another day, thanks to grandparents who couldn’t sleep
You may not look forward to sleeping less as you get older. But maybe it wouldn’t seem as bad if you knew it once played an important role in human survival.
A new study, published July 11 in Proceedings of the Royal Society B, suggests that the way sleep patterns change with age may be an evolutionary adaptation that helped our ancestors survive the night by ensuring one person in a community was awake at all times. The researchers called this phenomenon the “poorly sleeping grandparent hypothesis,” suggesting that an older member of a community who woke before dawn might have been crucial to spotting the threat of a hungry predator while younger people were still asleep. It may explain why people slept in mixed-age groups through much of human history.
“We may be looking at just another reason why grandparents were critical in human evolution,” said Alyssa Crittenden, an author of the study and an associate professor of anthropology at UNLV.
Researchers analyzed the sleep patterns of a society of hunter-gatherers in Tanzania called the Hadza. Thirty-three members of the Hadza community wore small watchlike tracking devices on their wrists for 20 days.
The Hadza sleeping environment may have similarities to that of earlier humans, researchers said. They sleep outdoors or in grass huts in groups of 20 to 30 people without artificially regulating temperature or light. These conditions provide a suitable window to study the evolutionary aspects of sleep.
Out of more than 220 total hours of sleep observation, researchers found only 18 minutes when all adults were sound asleep simultaneously. Typically, older participants in their 50s and 60s went to bed earlier and woke up earlier than those in their 20s and 30s. On average, more than a third of the group was alert, or lightly dozing, at any given time.
Protected wolves in Alaska face peril from beyond their preserve
Within the 2.5 million acres of the Yukon-charley Rivers National Preserve in cen- tral Alaska, wolves and other majestic animals are protected. But animals like wolves do not respect lines drawn on a map. And a recent study suggests that efforts to limit populations of these predators outside those borders is having negative effects on wolves living within the preserve.
The study, published in June in Wildlife Monographs, suggests that when Alaskan authorities were limiting wolf populations outside the Yukon-charley preserve, survival rates of wolves within the preserve were lower than usual. The findings highlight the notion that managing wildlife within human-imposed boundaries requires communication and cooperation with authorities beyond a preserve’s boundaries, and could have implications for wildlife management programs elsewhere.
Since the 1990s, the Alaska Department of Fish and Game has spent millions of dollars, first sterilizing wolves, then shifting to shooting and killing hundreds of the animals from helicopters (independently, it announced the planned suspension of the program next year). The wolves were targeted as part of an intensive predator management program in the Upper Yukon-tanana region aimed to increase the population of the Fortymile caribou herd in lands surrounding the preserve. Once estimated to number in the hundreds of thousands, the caribou herd fell to just 6,000 in the 1970s and now generally peaks at about 50,000 to 60,000. And evidence has built up suggesting that these efforts may be ineffective at increasing caribou in this area.
After 22 years monitoring wolves in the preserve using radio collars, the researchers, led by John Burch, a wildlife biologist for the National Park Service, were not surprised to find that wolf survival rates decreased during lethal management outside the preserve in the Upper Yukon-tanana Predation Control Area. “Every single wolf pack went outside the bounds of the preserve,” Burch said. The state never shot wolves inside it, but many wolves that left the boundaries of Yukon-charley were shot and killed.
What was surprising, however, was the intricate story that unfolded of how the wolves responded to control efforts. Surviving wolves inside the preserve tended to have more pups — but not enough to immediately offset those killed during predator control efforts.
“Even though they were adding more members to the pack, they were losing more than that, so in the average year, they ended up behind,” said Josh Schmidt, a biostatistician who led the population analysis. “They were not self-sustaining and were dependent on dispersing individuals coming in from other areas from outside of the area most likely.”
The targeted caribou herd, which was increasing before these efforts began, has reached more than 50,000 and is showing signs of nutritional stress, according to a study published in The Journal of Wildlife Management in January.
Hungry caterpillars that turned to cannibalism
If you’re a hungry caterpillar and you’ve got a choice between eating a plant or another caterpillar, which do you chose?
You pick your fellow caterpillar, scientists have found — if the plant is noxious enough.
In a study published July 10 in Nature Ecology and Evolution, scientists sprayed tomato plants with a substance that induces a defensive response — a suite of nasty chemicals — and found that caterpillars became cannibals instead of eating the plant.
“The plant rearranges the menu for the caterpillar and makes other caterpillars the optimal choice,” said John Orrock, an evolutionary ecologist at the University of Wisconsin-madison who led the study.
His team’s findings support a growing body of research suggesting that plant defenses are far more sophisticated than we have thought. Plants cannot run or hide, but they possess powerful strategies capable of altering the minds of herbivores that try to eat them.
The fight begins when an insect bites the plant, which triggers an immunelike defense response. The plant produces chemicals that hungry herbivores find toxic, unappealing or difficult to digest. For example, caffeine and nicotine, both toxic in high doses, are byproducts of the defense responses of tobacco and coffee plants.
Orrock and his colleagues knew that a chemical called methyl jasmonate, which smells like limes or flowers, could induce this defense mechanism in tomato plants. They also knew that caterpillars, which eat the leaves of tomato plants, will turn on one another when the going gets tough.
The scientists wondered how a plant’s defense system would affect the caterpillars if they combined these behaviors.
They sprayed tomato plants with either a neutral substance or varying amounts of methyl jasmonate to create graded levels of defense in the tomato plants. “You crank up the methyl jasmonate, the plant makes more nasty stuff,” said Orrock.
Then they put each plant inside an arena with eight caterpillars and watched for eight days to see how the caterpillars would handle two choices: Eat the plant, or eat your fellow caterpillar.
The caterpillars munched the plants with no extra defenses down to bare sticks before turning on one another for nourishment. But faced with the well-defended plants sprayed with lots of methyl jasmonate, the caterpillars gave up on the tomato leaves early. And like desperate characters in a cartoon island mirage, fellow caterpillars became appealing steak dinners.
Jupiter’s Great Red Spot gets its close-up
The Great Red Spot has never looked bigger.
NASA’S Juno spacecraft has been making repeated swoops just above the cloud tops of Jupiter. During the latest flyby, on July 10, the spacecraft passed about 5,600 miles above the Great Red Spot, a 10,000-milewide storm that has swirled for at least 350 years. NASA posted images from the flyby on the web on July 12.
Amy A. Simon, a scientist at NASA’S Goddard Space Flight Center in Greenbelt, Md., who studies planetary atmospheres, said the appearance of the spot may have changed since the end of NASA’S Galileo orbiter mission more than a decade ago.
“I would say the internal clouds look less sheared apart in some places, compared with Galileo,” she said. “We expected that, based on recent Hubble imaging, but these images are a higher-resolution view of those clouds and exactly how they’ve changed over the past decades.”
The released images look distorted. “The hourglass shape is because we are so close and the horizon is foreshortened,” said Candice Hansen-koharcheck, NASA’S lead investigator for the Junocam instrument.
Juno’s images are part of the mission’s outreach to the public, inviting “citizen scientists” to download the pictures for tweaking and enhancing.
Hansen-koharcheck pointed to one processed image submitted as part of the crowdsourced analysis effort. Adjustments put the view back into the proper, undistorted perspective and added a more vivid palette.