Lewis I. Held, Jr. is Associate Professor of Developmental Genetics in the Department of Biological Sciences at Texas Tech
University. He is a fly geneticist who has taught human embryology for 35 years. He studied molecular biology at the Massachusetts
Institute of Technology (BS, 1973), investigated bristle patterning under John Gerhart at the University of California, Berkeley
(Ph.D., 1977), and conducted postdoctoral research with Peter Bryant and Howard Schneiderman at the University of California,
Irvine (1977-86). This is his sixth scholarly monograph, following Models for Embryonic Periodicity (Karger, 1992), Imaginal
Discs (Cambridge, 2002), Quirks of Human Anatomy (Cambridge, 2009), How the Snake Lost its Legs (Cambridge, 2014), and Deep
Homology? (Cambridge, 2017).