Emergence is the way complex systems and patterns arise out of a multiplicity of relatively simple interactions. An emergent property can appear when a number of simple entities (agents) operate in an environment, forming more complex behaviors as a collective. The emergent property itself may be either very predictable or unpredictable and unprecedented, and represent a new level of the system's evolution. The complex behaviour or properties are not a property of any single such entity, nor can they easily be predicted or deduced from behaviour in the lower-level entities: they are irreducible. For example, no physical property of an individual molecule of any gas would lead one to think that a large collection of them will transmit sound. The shape and behaviour of a flock of birds or shoal of fish are also good examples.
According to an emergent perspective, intelligence emerges from the connections between neurons, and from this perspective it is not necessary to propose a "soul" to account for the fact that brains can be intelligent, even though the individual neurons of which they are made are not.
A broader example of emergent properties in biology is viewed in the biological organisation of life, ranging from the subatomic level to the entire biosphere. For example, individual atoms can be combined to form molecules such as polypeptide chains, which in turn fold and refold to form proteins, which in turn create even more complex structures. These proteins, assuming their functional status from their spatial conformation, interact together and with other molecules to achieve higher biological functions and eventually create an organism.
