It's the weekend, which means it is time for scientists, science journalists, book authors and intellectually curious readers to think about microbiology.  And that means beer. Beer is actually safer to drink than water. You didn't know that?  Let's talk some biology.

The master ingredient in beer is yeast. That's a microbe! So if you do experiments with beer this weekend, you are advancing the world of science.  If you make beer, you are a microbiologist.  If you drink beer, you are a microbiologist. Microbiologists understand beer and bacteria and stuff, which is why they drink beer more than water.

They can be a little flaky about other things.  When microbiologist Dr. Alex Berezow (editor of Real Clear Science, my co-author on Science Left Behind and, fascinating to me, recently hired by Elsevier to write the 2nd edition of "Biotechnology: Applying the Genetic Revolution") and I were in Texas for the 2013 Misfits Inauguration Ball, thrown by libertarian TV host Glenn Beck to highlight people in various fields who had annoyed the administration last year, I set out to show him the awesome power of a steak and a cigar.

When the waitress took our order, he ordered his steak 'well done', bordering on burnt, and the whole place went quiet. Steak artistes have some sort of Spidey Sense about these things and over Alex's shoulder I could see the staff holding back the chef on duty that night. Through that little glass porthole in the door to the kitchen I saw him waving a butcher knife and yelling in our direction, but luckily we couldn't hear what he said.

"Why would you order a steak well done in a restaurant?  That irritates chefs," I phrased it in the nicest possible way.

"I'm a microbiologist," he replied, as if that answered the question for anyone but the two of us.

But he was right in not worrying about microorganisms in his beer yet still making sure his steak was cooked far too hot to be tasty.  Like worrying about an asteroid hitting me in the head, or the chance that health care reform will lead to lower health care costs, some possibilities are so remote they don't merit concern, like me getting ill from a medium rare steak. Still, he was not wrong scientifically so I didn't make goat noises at him. There's icky stuff in raw steak.

Dr. Charles Bamforth of the University of California, Davis and author of FOAM, which I gushed over here on Science 2.0, is a member of the steering committee that recently produced a report on beer microbiology.  Unlike FOAM, which you have to buy (and really should), the FAQ is free. 

If you care about beer - and you do - this is bigger than DSM 5 or the next IPCC report, because the 18 members of this committee were not chosen based on geographical or gender or racial quotas, like the IPCC, or patched together by every possible special interest in psychology, like DSM 5, the members were instead selected because they know the most about beer and microbiology.  There's no politics in beer microbiology, the American Academy of Microbiology don't roll that way.

Their conclusion: Yeast matters.

They even create the Beer Tree of Life to make it a lot more relevant to everyday people - by showing where beer parts fit:

See? Yeast is on OUR side. Credit:American Academy of Microbiology

That's right, you and yeast are not so far apart after all. Yeast is such a popular model organism for learning how cells work because it is a highly sophisticated, complex product of evolution - which means beer is too. And always has been. Beer drinking songs are documented scientifically farther back in civilization than prostitution (despite Big Ho public relations campaigns claiming they are the oldest profession), which shows how important beer has always been to ancient science. 

Yeast is not just evolving in a random walk or due to natural selection, of course. Like 100% of food products today, it has been genetically modified by humans over time.  Ever since early man tasted the first beer due to the first fermented grain sprout, they worked on ways to make it better.  And in doing so, they made the entire world healthier.

I don't want to spoil the whole plot but I will answer why you should drink beer instead of water. Fermentation breaks down simple sugars, which produces alcohol and carbon dioxide.  Yeast evolved to do that, to gain a leg up against other microbes, because lots of other microbes can't handle the acidity of CO2 and organic acids produced by yeast. Or alcohol.  Beer has both.

Yet those microbes survive just fine in water. We might never have survived to create modern sanitation in the 1800s if we only had unclean water to drink. Beer saves lives. That is why at our dinner Alex did not drink the agua, but he had another brew, just to be extra healthy while eating that steak.

Read more FAQ: If the Yeast Ain't Happy, Ain't Nobody Happy: The Microbiology of Beer