Hox genes, flies and humans
American scientists Mike Levine and Bill McGinnis discovered Hox genes in 1984, when they were studying fruit-fly embryos. In the fly embryo, Hox genes control in which body sections the wings, legs and antennae end up. Changes in Hox genes can have drastic results - for example, flies with feet in place of antennae. All animals have Hox genes. Amazingly, your body plan is laid down using Hox genes similar to those of a fly. Hox genes are 'master switches', which themselves switch other genes on and off.