The Sacred Cow and the Abominable Pig:

a cow getting its flatulance harvested as methane gas... or perhaps it's about to be blasted out into space, personally I find the second one more likely.

"Riddles of Food and Culture" originally published as "Good to Eat" by Marvin Harris.

I was already hopeful about this book before picking it off the shelf because it's by Marvin Harris who wrote one of my other favorite books of all time, "Cannibals and Kings". There's no getting around this being a dry book as far as nonfiction goes, and, because it was copywritten in 1990, the text definitely has a dated feel. However, if you're looking for a book that tells everything about how something completely common and mundane in one part of the world and why it's exotic and taboo in yet another part, this is an excellent choice. This book is all about why people eat what they do: why there are sacred animals, pariah animals, food animals, and pet animals and how they all interweave and mingle, sometimes maintaining more than one role at a time.
Harris is great as an author because he takes common explanations of behavior and studies them closer, bringing in real data and figures, actual case scenerios, and complicated evaluation of each idea. He never takes a "common sense" and well-repeated explanations at face value and actually seems to find particular delight in proving them unlikely at best. Harris goes chapter by chapter explaining the eating habits of the known universe down to which piece is consumed when and how often and by whom and on which Tuesday of the month. His specificity is exacting and that's part of what makes his books so fascinating. He seeks to not only notate what and where but seeks to fullness the answer to "why?" If you like to know how things work and, of course, a better idea of why things work the way the do, check this piece out. You will immediately know more about the food culture of the entire world than anyone else you will ever meet and inserting bits of Harris' tidbits into conversation make you sound really smart at those cocktail parties you've been going to.