Different genes, same result: How flies evolved multiple ways to define heads and tails

One of the most important milestones in the early life of an organism is when the embryo breaks symmetry and arranges itself to form the head (anterior) at one end and tail (posterior) at the other end. Scientists have used the common fruit fly (Drosophila melanogaster) for decades as a model species to study the process of forming the anterior-posterior body axis, along with countless other early developmental and genetic processes.