Hepatitis C is, in some ways, a high-profile disease. Worldwide, an estimated 200 million people are infected with the virus. Some of them will suffer cirrhosis, liver cancer and even death. Celebrities like Steven Tyler of Aerosmith and “American Idol” have spoken publicly of their infections. 

But mysteries still shroud the disease. Typically spread through drug injections, blood transfusions and sexual contact, hepatitis C can quietly cause liver damage for 20 years or more before victims become aware that they are ill. “Worldwide, it’s causing devastation,” said Brian Edlin, an epidemiologist at SUNY Downstate Medical Center in Brooklyn.

Continue reading “Viral Outbreaks in Dogs Yield Clues on Origins of Hepatitis C” →

In the early 1900s, scientists discovered that each person belonged to one of four blood types. Now they have discovered a new way to classify humanity: by bacteria. Each human being is host to thousands of different species of microbes. Yet a group of scientists now report just three distinct ecosystems in the guts of people they have studied.

Blood type, meet bug type.

“It’s an important advance,” said Rob Knight, a biologist at the University of Colorado, who was not involved in the research. “It’s the first indication that human gut ecosystems may fall into distinct types.”

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Ever since Darwin, biologists have recognized that life evolves. But in the past 25 years, some researchers have argued that certain organisms are better at evolving than others. Their genomes have a flexibility that lets them adapt effectively. The less evolvable species, by contrast, are too rigid to take advantage of new mutations or to find new solutions for survival.

Many biologists agree that evolvability makes sense in theory. But finding evidence of it in the natural world has proved difficult.

Continue reading “Tortoise and Hare, in a Laboratory Flask” →

When humans domesticated dogs at least 10,000 years ago, an apparent side effect was a bizarre new kind of parasite. A canine cancer gained the ability to spread from one dog to the next, creating new tumors along the way.

Today, it thrives in dog populations around the world. Scientists are now studying canine transmissible venereal tumors (or C.T.V.T.) to uncover the adaptations the disease uses to thrive in its peculiar way. In the current issue of Science, British scientists report that it upgrades its energy supply by stealing new parts from its canine hosts.

Continue reading “Canine Tumor Fuels Up by Stealing Parts From Host, Report Says” →