Realities are a complex, evolving attribute of the human species, as well as a necessary part of the individual mind. Truth is an absolute certainty. Humans have only versions of truth, or realities, which are used as substitutes. Each reality is thought to be the Truth by its advocates, but all human realities can be seen as changing over time and varying from culture to culture. Truth cannot change.
Realities change to keep up with changing situations and data.
We are, in effect, clueless about the true nature of our existence, so we must create our own reality. Realities are a necessity for all living things, although they vary from the rudimentary to the complex. For humans and other vertebrates, reality is constructed in the mind of the brain. The mind is directly responsible for dealing with the material world for the body-colony. It needs a model of the material world as a frame of reference for the information taken in from the senses.