Marcus Kehrli, an immunologist and veterinarian with the U.S. Department of Agriculture in Iowa, was flying to Marco Island, Florida, but he wasn’t thinking about sun and surf. Nor was he thinking about the meeting he was traveling to, an important conference on leukocytes (the white blood cells of our immune system). What he was thinking about during that flight in October 1989 was a dead calf.
Kehrli has thought about cows most of his life. He grew up on an Iowa farm and has milked cows since he was three, and whenever he talks about them, an evangelical tone creeps into his voice. Since we are mammals, Kehrli says, milk is nature’s most perfect food. One look at his honest midwestern face and you know it’s no use even arguing the point. Kehrli loves cows.
On the plane, Kehrli was working on an article about his troublesome calf, which ...
