Bees are a group of insects closely related to wasps. The first bee evolved from its wasp ancestor about 120 million years ago, when it started using the pollen of plants as a food source for its young. At about the same rime in the evolution of life on our planet, the flowering plants were becoming very common. A great mutualism formed: the flowering plants provided food for bees, and, in return, bees moved pollen from one plant to another (pollination). Over the next 120 million years, the flowering plants flourished into the huge diversity we see today and the bees evolved into a diverse, common and important group of insects.