Cooperation is not unique to humans; it is part of nature, down to the cellular level. From these biological blocks, cooperation prevails at every level of the animal kingdom -- ants that march to the same drummer move faster, fish rid other fish of harmful bacteria for a free meal, small birds protect each other from predators, bats that share food survive. According to evolutionary biologists, cooperation is one of the most important and beneficial behaviors on Earth. We literally would not be here without it.
