Lying has played an important role in the evolution of humanity.
Being able to cheat others out of resources obviously confers
advantages upon the deceiver, but it also creates a selection
pressure for cheater-detection. Evolution simultaneously
develops better cheaters and people better at spotting and
stopping them. This eternal battle is the key to the success of
our species, since being able to detect cheaters allows us to
co-operate in the knowledge the favour will be returned. Even
the most successful hunter only makes a kill once a month or so,
and is reliant upon getting food from others for the rest of the
time. If everyone could freely cheat each other the incentive to
share would be lost, since there is no guarantee the investment
will be repaid. So the hunter starves to death. This makes
cheat-detection very important, especially to humans. We are one
of the few species almost entirely reliant upon such reciprocal
altruism for survival. At the same time we are one of the
easiest species to cheat,