The litany of direct health impacts associated with climate change is becoming well known. A rapidly warming world brings more heat-related deaths, more disease spread through contaminated food and water and by insects, and more injuries from more extreme storms. The most vulnerable individuals are the elderly, the very young and the medically infirm. And the most vulnerable people live in the poorest nations, which are least responsible for causing climate change and least able to cope with the consequences. But a pair of ailments is rising faster in rich nations than in poor ones: asthma and allergies.

These two respiratory illnesses are epidemic in the developed world, and the numbers are rising. In the U.S. alone, at least 50 million people suffer from allergies, costing $18 billion annually in health care. Asthma affects one in 14 American adults, almost one in 10 children, and is the leading cause of school absences. The more people are exposed to air pollution and pollen, the worse their symptoms are, and the more likely they are to develop additional allergies.

The heart relies on four valves that act as one-way gates, controlling blood flow out of each of the heart's four chambers. The mitral valve between the two left chambers of the heart has two leaflets, or cusps; the tricuspid, pulmonary and aortic valves each have three. The leaflets swing open and shut like saloon doors with every beat, maintaining a steady blood supply. (A person's heart generally beats 80 million times a year and five to six billion times over the course of a normal lifetime, according to Irvine, Calif.–based valve producer Edwards Lifesciences.)

Slide Show: Artificial heart valve improvements over the past 50 years [More]

The bizarre deaths of 21 polo ponies at last weekend's U.S. Open Polo Championship in Wellington, Fla. might have been caused by something in vitamin injections the horses received, the captain of the ponies' team has told reporters. Experts suspect that contamination or improper dosing of the cocktail are blame, but they say it's impossible to say just what killed the horses before the results of toxicology studies are released. [More]

Last week I found myself in a web video dialogue on Bloggingheads.tv. This is a sort of video blogging website sponsored by the New York Times where the two participants are meant to rally big ideas back and forth, or at least get a decent dialogue going about the topic at hand. I spoke with (soon-to-be) Yale philosopher Joshua Knobe on bloggingheads.tv on the natural foundations of religion. Our discussion was the first of a John F. Templeton Foundation series called Percontations, a term defined as “questionings or inquiries, especially those requiring more than a yes or no answer.” In the present context, this inquiry presumably concerns the achingly dull question over whether or not God exists. [More]

As evidence of widespread vitamin D deficiency grows, some scientists are wondering whether the sunshine vitamin--once only considered important in bone health--may actually play a role in one of neurology's most vexing conditions: autism. [More]

Spider silk alone is stronger than steel, but researchers in Halle Germany have found that it can be made even stronger. A new paper, published today in Science reports that spider silk can be infused with metals such as aluminum, zinc and titanium. [More]

On the frozen plains of the Siberian tundra, a reindeer herder chances upon a 40,000 year old baby mammoth ? the most perfectly preserved mammoth ever found. On Sunday, witness the mammoth?s unveiling to the world, as scientists reveal her incredible story. Click to meet the Baby Mammoth now >> natgeotv.com/mammoth

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Out of Our Heads: Why You Are Not Your Brain, and Other Lessons from the Biology of Consciousness by Alva Noë. Hill and Wang, 2009