Gates isn’t shy about proclaiming Smil, a professor emeritus at the University of Manitoba, his favorite author. In fact, he's recommended several of Smil's books before.
As usual, Gates writes, Smil attacks the issue of whether humans should consume meat from every possible angle. First he tries to define meat; then he looks at its role in human evolution, as well as how much meat each country consumes, the health and environmental risks, and the ethicality of raising animals for slaughter.
Gates, who was a vegetarian for a year during his 20s, is especially impressed by how Smil uses science to debunk common misconceptions, like the idea that raising meat for food involves a tremendous amount of water. In fact, Gates writes:
Smil shows you how the picture is more complicated. It turns out that not all water is created equal. Nearly 90 percent of the water needed for livestock production is what’s called green water, used to grow grass and such. In most places, all but a tiny fraction of green water comes from rain, and because most green water eventually evaporates back into the atmosphere, it's not really consumed.
Overall, the book left Gates feeling that eventually, "the world can meet its need for meat."