Beer is the world's most commonly fermented beverage and lager beer commands 94 percent of the global market. Making the beer possible is a biological oddity: a hybrid yeast that combines two distinct species and confers the ability to make cold-brewed beer, a product that first emerged 500 years ago in Europe.

 Without question, the domesticated hybrid yeast that gives us lager beer is an organism worth many billions of dollars, but just how Saccharomyces cerevisiae, the well-known domesticated yeast that gives us wine and bread, combined with Saccharomyces eubayanus, a yeast species only recently discovered in nature, to give us the hybrid organism that makes cold-brewed beer remains a mystery.

Moral judgments, ideas about good or bad, remain the building block of cooperation in a large group.

A rule of thumb for promoting cooperation is to help those who have a good reputation and not those who have a bad reputation, yet that determination requires time, effort and money. What about moral "free riders" who evade the cost associated with moral judgment (e.g. by not paying taxes for police and court) so are better off than those who shoulder the cost?

Philosophers debate voluntary reactive policing of the moral free riders, which is costly, too, and thus can be exploited by higher order moral free riders. This leads to an infinite regression of opportunities to free ride.

Can the moral free rider problem really be solved? 

It is time for NHS England to "do the right thing" and fund pre-exposure prophylaxis (PrEP) for HIV prevention, argue two senior public health doctors in The BMJ today.

Directors of public health Jim McManus and Dominic Harrison, say despite overwhelming evidence that PrEP against HIV infection is largely safe, effective, and cost effective, NHS England has declined to make it available on the NHS, arguing that HIV prevention is the responsibility of local government.

Such an approach, they write, "confounds its advocacy of a health and care system integrated around the best outcomes for the citizen and perpetuates an incoherent national approach to HIV prevention."

Current federal agricultural subsidies focus on financing production of food commodities, a large portion of which are converted into high-fat meat and dairy products, refined grains, high-calorie juices and soft drinks (sweetened with corn sweeteners), and processed and packaged foods.

Karen R. Siegel, Ph.D., of the Centers for Disease Control and Prevention, Atlanta, and coauthors used data from the National Health and Nutrition Examination Survey from 2001 to 2006 to calculate an individual-level "subsidy score" for consumption of subsidized food commodities as a percentage of total calorie intake.

The study, which relied on a single day of 24-hour dietary recall, included 10,308 participants, about half of whom were men, with an average age of about 40.

In the insect world, smells are important. Insects of course do not have noses, but they do have receptors on their antennae, feet, and other body parts that allow them to sense chemicals and odors.

Female parasitoid wasps and flies are known to hone in on their hosts (caterpillars, cicadas, and other insects and arthropods) by "smelling" them -- that is, they sense chemicals from other insects that attract them. Once they find the hosts, they lay eggs on or inside them, and the young that emerge from the eggs feed on them.

ANN ARBOR -- A new reconstruction of Antarctic ocean temperatures around the time the dinosaurs disappeared 66 million years ago supports the idea that one of the planet's biggest mass extinctions was due to the combined effects of volcanic eruptions and an asteroid impact.

Two University of Michigan researchers and a Florida colleague found two abrupt warming spikes in ocean temperatures that coincide with two previously documented extinction pulses near the end of the Cretaceous Period. The first extinction pulse has been tied to massive volcanic eruptions in India, the second to the impact of an asteroid or comet on Mexico's Yucatan Peninsula.