A vital gene that defends us against cancer has been found in one of the simplest of animals – a flat, amoeba-like creature called a placozoan. The discovery shows that p53, sometimes described as the “guardian of the genome”, has been around for over 1 billion years

Placozoans are so simple that it’s hard to conceive of them as animals at all. They have no tissues or organs, no front or back, no left or right. They look for all the world like amoebas, with flattened bodies that are just a few cells thick. There’s only one confirmed species, Trichoplax adherens, although the existence of a second is disputed. Depending on who you believe, the Placozoans are either at