A new study has revealed how the repurposing of an ancestral gene saved the embryos of cod's ancestors from extinction, enabling them to form the large populations that, millions of years later, would change the course of human history. The codfishes and their relatives in the order Gadiformes lost genes essential for egg buoyancy and the survival of their embryos, yet survived by adaptively recruiting mechanisms that aid egg ovulation in freshwater fishes. ...read more read less