Recent research has shown that complex organisms such as humans have more in common genetically with a very simple organism, sponges. This similarity mainly lies in gene regulation, or how and when a certain gene is activated. The ability of organisms to turn certain genes on and off was thought to be reserved for higher life forms, however even an organism as simple as a sponge posses this ability. Scientists used to believe that the complexities of different animals was dictated by the number of genes they had, but they've recently discovered most animals have a similar number of genes. This lead them to believe that gene regulation is actually what has driven evolution and lead to such a wide animal diversity. Being that the sponge is one of the oldest multicellular organisms it can be inferred that the gene regulation has at least been present for 700 million years, or the time that the common ancestor of sponges and people was present. This shows a key connection between gene regulation and evolutionary diversity.