The food you ate today for breakfast has been transformed. Your body has used some of it to generate energy and some to build new tissues. Your body controls your metabolism in a marvelously sophisticated way, channeling resources to each organ to keep it functioning. In my new “Matter” column for the New York Times, I look at how our metabolism evolved. It turns out that our brains and our muscles have an odd kind of metabolism compared to other mammals. Did we lose muscular strength to fuel a big brain? Or did we switch our muscles to a different kind of metabolism, which let our brains burn brighter? The answer’s not clear yet, but the research is pretty cool. Check it out.