The various phyla appear in the Cambrian explosion, 542 million years ago. They are already markedly different from each other, but the existence of the Hox genes in most of them proves there must have been some older shared ancestor. read more
Although the last common ancestor of humans, fruit flies, worms and yeast lived over a billion years ago, there are still many genes we share that betray our common heritage. About 30% of fruit fly genes crop up in C. elegans and 20% of fly genes can be found in yeast. read more