【推荐2】New York’s Central Park has a statue dedicated to him, and there’s even been a movie about him: a sled dog named Balto. Now he is the focus of a DNA study, 90 years after he died, to see what made the dog so famously tough (坚韧).

In 1925, this Siberian husky was part of an expedition in Alaska called the serum run, the goal of which was to bring life-saving medicine to young people that were threatened by a deadly disease in the remote town of Nome, over 600 miles away. Balto led the long-distance stretch, and wound up getting most of the honor.

After Balto’s death in 1933, his remains were preserved and put on display at the Cleveland Museum of Natural History.

“Balto’s fame and the fact that he was taxidermized gave us this cool opportunity 100 years later to see what that population of sled dogs would have looked like genetically and to compare him to modern dogs,” said Katherine Moon, a postdoctoral researcher at the University of California.

Her team took skin samples from the dog’s belly and reconstructed its genome — the complete set of genes in an organism. They compared this genetic material with that of 680 contemporary dogs from 135 breeds.

Contrary to a legend that thought that Balto was half wolf — as suggested in an animated Universal Pictures film that came out in 1995 — this analysis found no evidence he had wolf blood. It turned out Balto shared ancestors with modern day Siberian Huskies and the sled dogs of Alaska and Greenland.

Moon’s team also compared Balto’s genes with the genomes of 240 other species of mammals.

This allowed researchers to determine which DNA fragments (片段) were common across all those species and have not therefore changed over the course of millions of years of evolution. This stability suggests that these fragments of DNA are associated with important functions in the animal, and that mutations (基因突变) there could be dangerous.

The bottom line from the research was that Balto had fewer potentially dangerous mutations than modern breeds of dogs did, suggesting he was healthier.

【推荐3】Carers at a place called TRC waved a happy goodbye this week to Bear, a much-loved green sea turtle (龟) who swam to freedom from Mooloolaba Beach. Bear was found injured on a shore in February. Its bone was injured and it was covered by small harmful creatures. Bear spent 116 days receiving care at TRC.

Though Beal’s carers got to know him well—such as what food he preferred and that he was very cheeky—it was important he didn’t become too used to being cared for by people. “When we care for a turtle. we’d try to communicate as little as possible,” Ms Attwood said. “When a turtle is sent back into the ocean, we don’t want them to rely on humans for food. They need to know how to search for food themselves. The one time we may need to communicate with a turtle more often is if they need any special treatments.”

So where will be Bear? Bear will most likely stay swimming around the Indo-Pacific area. Green turtle loves to eat sea grass, which is why coral reefs (珊瑚礁) are always a popular place. The Great Barrier Reef is a common area turtles like to visit. Bear is now carrying certain equipment, so his former carers and turtle experts around the world will be able to follow where he goes in the future.

Bear is a type of green sea turtles. They’re called green sea turtles because they have green fat under the back. We can tell them apart from other kinds of sea turtles because they have only a pair of scales (鳞) in front of their eyes. And green sea turtles are the largest types of sea turtle. They grow to about 110-190 kg. But they are dying out due to humans who want their eggs, meat and skin. Some are accidentally caught by fishing ropes.

【推荐2】There was a strange stillness. The birds, for example—where had they gone? Many people spoke of them, puzzled, and disturbed. The feeding stations in the backyards were deserted. The few birds seen anywhere were dying; they trembled violently and could not fly. It was a spring without voices. On the mornings that had once throbbed (跳动) with the dawn chorus of robins, catbirds, doves, jays, wrens, and scores of other bird voices, there was now no sound; only silence lay over the fields and woods and wetlands.

Rachel Carson was a scientist by profession. But these lines from the opening chapter of her 1962 book Silent Spring, A Fable for Tomorrow, show her talent as a writer. By imagining a world without birds, she aimed to alert not only the scientific community but also the public to the damaging effects of human activity on ecosystems—in particular, to the harmful use of pesticides, such as DDT. She believed that the chemical industry was knowingly causing harm to plants, animals and even humans, and wished to see pesticides used in a more responsible, limited and carefully monitored way.

Carson urged people to make themselves aware of the facts and do something about the situation. Silent Spring contains a lot of scientific research and case studies. The book details the gypsy moth wipeout programme, which killed birds. The Book also gives examples of other wipeout programmers that did nothing to reduce the problems they were originally designed to solve.

Carson’s message caused a great increase in environmental awareness. Its impact was immediate and far-reaching: The use of DDT was banned and the Environmental Protection Agency(EPA)was established in the US. Silent Spring was therefore regarded as a milestone in the launch of the green movement in the Western world.

Her book not only changed the world; half a century later it remains a book that deserves to be reread today. Unless we do listen to Rachel Carson’s warning, one day we may wake up to the strange and quiet horror of another silent spring.