Heredity is Lawless
Here’s how Carl Zimmer defines a scientific law in his awesome book on heredity, She has her Mother’s Laugh : “A scientific law predicts some aspect of the universe, usually with a short, sweet equation.” By that token, he says something almost blasphemous for a book on heredity: “The patterns (Mendel) saw wasn’t really a law.” Huh? Is it because Mendel’s Law doesn’t have a “short, sweet equation”? Nope: “(Other scientific laws) were as true thirteen billion years ago in the universe’s infancy as they are true today. Mendel’s law has far narrower boundaries.” For example, take microbes: “None of them follow Mendel’s Law.” Why not? Two reasons. One, microbes reproduce via the parent splitting into two (children). Whereas Mendel’s Law describes heredity from two parents (aka “vertical inheritance”). Two, bizarre though it may sound: “(Microbes) can also inherit genes from unrelated microbes, through horizontal inheritance.” Next, here’s a reminder tha...