March 5, 2012
You’ve no doubt heard about the myriad effects of rising global temperatures: droughts, drying rivers, lowland floods, plummeting populations of polar bears and Emperor penguins, coastal storms putting Arctic villages in mortal danger. Now there’s a new victim: the future of Canadian ice hockey.
To those of us who don’t follow sports, it might seem like a silly thing to fret over. But ice hockey is actually quite important to the culture and economy of Canada. The first organized game of indoor hockey, in 1875, took place in Montreal. When the country sent its first astronaut into space, he took a hockey stick and puck with him. Every year, according to one report, more than one-fifth of the country’s adult population attends or plays in an ice hockey game.
Because a lot of this hockey fun takes place in outdoor ice rinks, the scientists behind the new study wondered if the sport has been influenced by the changing climate. Since 1950, average winter temperatures in Canada have gone up 2.5 degrees Celsius, while the duration and intensity of cold spells have decreased.
In their report, published today in Environmental Research Letters, the researchers analyzed historical data from 142 weather stations to calculate the length of the annual outdoor skating season between 1951 and 2005. (They based this simply on whether the temperature was cold enough to keep ice frozen in the rink.) For a few places, the skating season has crept up earlier in the fall. For most areas, though, the length of the season has become much shorter.
The prairies—which include Alberta, Manitoba and Saskatchewan—and southwest Canada saw the biggest temperature changes. If these trends are extrapolated into the future, the researchers predict that by the middle of the century, some of these regions will no longer have days cold enough to sustain an ice rink.
The last sentence of their study is sure to tug at the heartstrings of any Canadian hockey fan: “Wayne Gretzky learned to skate on a backyard skating rink; our results imply that such opportunities may not available to future generations of Canadian children.”
March 2, 2012
During the last glacial period, from about 100,000 to 12,000 years ago, most northern parts of the world were covered in sheets of ice, wiping out any possibility of vegetation.
Well, not quite. It seems that pine and spruce trees, at least, were able to survive in certain spots in Scandinavia, according to DNA analyses reported in today’s issue of Science.
Researchers first analyzed mitochondrial DNA, which accumulates mutations slowly over generations, from modern Scandinavian trees. They identified two distinct lineages.
The first appears in trees from Scandinavia as well as those scattered across southern Europe. This evidence fits with a previously accepted theory saying that trees survived the glacial period only in more temperate Southern regions and then, once the ice began to melt about 9,000 years ago, gradually made their way back up north.
But the researchers also found a much older lineage—that is, samples with more genetic mutations in their mitochondrial DNA. This lineage was limited to trees in a small region of western Scandinavia. Because of its proximity to the relatively warm Atlantic Ocean, this particular spot had ice-free patches during the glacial period, presumably allowing some trees to survive.
To test this hypothesis, the team also looked at the DNA of ancient pollen found in cores of ice from Norwegian lakes. The pollen showed that trees grew nearby as long as 22,000 years ago, despite being surrounded by ice.
As well as uprooting the trees’ ancestral history, the new study could help researchers identify the genetic variations that allowed these species to be so flexible during a period of dramatic climate change.
March 1, 2012
We’ve all caught grandma or grandpa catching some z’s after a big meal, or while watching TV, or apropos of nothing at all. Popular wisdom says that older people tend to have restless sleep and more fatigue during the day.
That may be true, but a huge survey published today in the journal Sleep finds that elderly people are more satisfied with their sleep habits than people in any other age group.
The data was gleaned from a large survey, called the Behavioral Risk Factor Surveillance System, in which researchers called random people in the United States who were 18 years or older and asked them about their sleeping patterns, as well as more general questions about about race, income, education, mood and general health. The new sleep study included responses from more than 155,000 participants.
Some of the answers were fairly predictable. For example, people who are sick or depressed tend to report more sleep disturbances and daytime fatigue. And middle-aged women—who could be stressed from the demands of raising children or the hormonal fluctuations of menopause—have the most sleep complaints.
The most surprising result concerned the elderly. When the data were adjusted to account for sickness and depressed moods, it showed that the best sleep reports come from men and women over age 80.
The researchers offer a few possible explanations. It could be that young people are losing sleep because of their increased reliance on technology, or from longer work hours. Alternatively, people who live past 80 could to be more resilient to the effects of chronic disease (which often affect sleep) than are those who die in their 60s and 70s.
As people get older, they tend to lower their standards of what it means to be healthy. So it could be that these seniors simply have a rosier opinion of their sleep patterns than other, more objective measures suggest. For example, in 2004 a large meta-analysis of people aged 5 to 102 years found that overall sleep time drops with age, by about 10 minutes per decade. So when you see grandma taking a nap, let her sleep. She might wake up feeling refreshed—or, at least, content.
February 29, 2012
If you ever visit Spitsbergen, Norway, one of the islands of Svalbard archipelago in the Arctic Circle, you might come across coal mines, snowmobile traffic, glaciers, polar bears and reindeer. Or a giant metal box sticking out of a mountain.
Four years ago this week, researchers erected the sturdy, if homely, box called the Svalbard Global Seed Vault, or less formally, the Doomsday Vault, to store a variety of frozen seeds in case of disaster. Nearly 25,000 new samples will be added to the cave this week, bringing the total inventory to more than 740,000 specimens. Covered in rock and permafrost, the vault will stay chilly even if the electricity goes out. It is, its backers say, “the ultimate insurance policy for the world’s food supply.”
Why such a massive hoarding effort? Researchers have long been worried about the loss of crop diversity, for many reasons. All over the world, rapidly changing climates mean that crops that used to be successful may suddenly fail. Similarly, a growing interest in conservation means researchers are trying to find crop varieties that don’t require as much land or damage to natural resources. What’s more, as the global population increases, so does demand for food.
Large collections of seeds (in Svalbard and elsewhere), together with living seed gene banks across the world, will help scientists of the future shape new varieties with useful traits, whether that’s stamina in dry spells or plentiful harvests.
The varieties added to Svalbard this week illustrate the wide range of the collection. One is the pretty red amaranth, a high-protein and gluten-free grain that was a favorite of the Aztecs and the Incas. Another, barley from the Pamir Mountains of Tajikistan, thrives in both hot summers and snowy winters. Surprising Science readers may be most familiar with a malting barley grown today the Northwestern United States. The grain, known as Klages, is a popular ingredient in craft beers.
February 28, 2012
For most animals, the number of males in a population is about the same as the number of females. And that makes sense, evolutionarily. If a population were skewed toward females, for instance, males would become a hot commodity and each one would have a better chance of mating than would a male in a balanced population. Eventually, parents who had boys would accumulate more grandchildren, and the genes for producing boys would spread until the sex ratio evened out.
But that explanation, known as Fisher’s Principle, is too pat. There are many species that, for a variety of environmental and social reasons, wind up with an imbalance of males and females. Typically, researchers have said that the female—usually the one that invests more time and energy into her offspring—is responsible for skewing the ratio depending on her needs. But a new study in pygmy hippos, published today in Nature Communications, shows that males can influence sex ratios, too.
In the wild, pygmy hippopotamuses live long and solitary lives in the swamps and forests of West Africa. Males compete, often to the death, for control of territory. Males and females meet only for mating, and then go their separate, reclusive ways.
Because the animals are nocturnal and males and females look exactly the same, researchers don’t know much about how pygmy hippos mate in the wild. In zoos, though, the hippos reproduce easily and, intriguingly, make more girls than boys. Of animals born in captivity, just 42 percent are male.
To find out why, researchers analyzed semen samples from 10 male pygmy hippos. In hippos, like humans, the mother’s egg always contributes an X chromosome to the offspring, whereas the father’s sperm cell will hold either an X or a Y chromosome. In a study published this morning, researchers used colored dyes to distinguish X-carrying sperm from Y-carrying sperm. They found that the average proportion of Y-carrying sperm was 43 percent—almost exactly the proportion of male hippos at birth.
The $64,000 question of course is why it would be an advantage for male hippos to have more daughters than sons. The researchers can’t say for sure, and the balance probably changes with environmental conditions, but they speculate that it’s a survival strategy in times of high population density (which the hippos may feel in captivity). When there are too many males, competition for territory will spike, leading to death matches between two brothers or between father and son—an evolutionary dead end.