All evolutionary processes depend on information being copied with variation and selection. Most living things on Earth are the product of evolution based on the copying, varying, and selection of genes. However, once humans began to imitate, they provided a new kind of copying and so let loose an evolutionary process based on the copying, varying, and selection of memes. This new evolutionary system co-evolved with the old to turn humans into more than gene machines. We alone on this planet, are also 'meme' machines. We are selective imitation devices in an evolutionary arms race with new replication processes. This is why we are so different from other creatures, this is why we alone have big brains, language, and complex culture.
Susan Blackmore, in "What Makes Us Human?"