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.
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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.
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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.”
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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.
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How do scientists reconstruct the climate of the past? They often turn to ice cores or growth rings from trees or deep-sea corals. But a new study gleans a wealth of weather intel from a largely untapped source: old documents.
Researchers from Spain scoured manuscripts from 9th- and 10th-century Baghdad, in modern-day Iraq, for references to the weather. Baghdad, where the Tigris and Euphrates Rivers meet, was at that time the new and bustling capital of the vast Islamic Empire, which stretched from India to the Atlantic Ocean. Much was written about the city and why it was chosen as the capital, including its population size, agricultural potential and climate.
In the 10 analyzed texts, most of which give exhaustive political histories of the region, the researchers found 55 meteorological citations, many of which were referring to the same event. The study points out that although the social and religious content of the documents is probably biased, the historians weren’t likely to fabricate an off-hand mention of a drought, hail storm or solar eclipse.
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In the 1930s, the Austrian biologist Karl von Frisch, of waggle-dancing honey bee fame, performed some little-known experiments on dancing minnows. The fish weren’t dancing for fun.
Von Frisch showed that when a minnow’s skin cells are damaged, as happens during a predator attack, the fish releases a chemical into the water that triggers nearby fish to flee. Von Frisch called the chemical “Schreckstoff,” German for “scary stuff,” and yesterday, scientists described its chemical makeup.
The research team first separated the skin mucous of zebrafish into its different chemical components and then tested how each affects the behavior of a group of fish in a tank. One of the chemicals, a sugar called chondroitin sulfate, caused a dramatic fear response.
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Smithsonian’s Surprising Science, February 2012.
The new study, certainly not the last word on DNA, was published last week in The EMBO Journal. The music is Chopin’s Minute Waltz, the subject of another post.
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For the past 10 years or so, there’s been a surge of interest among archaeologists in the people who discovered the New World. Most of the buzz revolves around when, exactly, those nomads crossed the Bering land bridge into Alaska, with a focus on the distinctive stone tools they used. Nobody talks much about the artistic leanings of the first Americans, simply because examples of their cave paintings, jewelry or other symbolic creations are few and far between.
But in July 2009, after seven years of excavation work, researchers found a humble stick figure engraved in bedrock in Lapa do Santo, in central Brazil. In their report, published yesterday in PLoS ONE, the scientists call it the “oldest, indisputable testimony of rock art in the Americas.”
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When human urban habitat runs into the terrain of other species, the results can be traumatic for many of the parties involved.
Take coastal southern California, which has seen a big population boom in the past couple of decades. As people built skyscrapers and condos and highways to accommodate their growing numbers, they inadvertently split up the natural habitats of lizards and birds, bobcats and coyotes, and loads of other species. Isolated to much smaller patches of habitat (not to mention surrounded by metal, concrete and plastic), the animals wind up with a much smaller gene pool, making them more susceptible to disease, climate change and natural disaster.
Since the 1960s, a solution often trumpeted by conservationists is to build a “wildlife corridor”: a green pathway that connects one patch of habitat to another, allowing species to move across wider areas despite human developments. These corridors exist or are being built all over the world, from jaguar habitat in the Americas to hardwood forests in Bhutan to tropical rainforests in Australia.
But two active corridor builders are now questioning whether the approach is a good one.
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