Witness Credibility: Humans and Other Animals Are Natural-Born Liars

David Livingstone Smith, Natural-Born Liars. Why do we lie, and why are we so good at it? Because it works Scientific American Mind (online) June 2005:

... Why do we lie so readily? The answer: because it works. The Homo sapiens who are best able to lie have an edge over their counterparts in a relentless struggle for the reproductive success that drives the engine of evolution. As humans, we must fit into a close-knit social system to succeed, yet our primary aim is still to look out for ourselves above all others. Lying helps. And lying to ourselves--a talent built into our brains--helps us accept our fraudulent behavior.

Passport to Success

If this bald truth makes any one of us feel uncomfortable, we can take some solace in knowing we are not the only species to exploit the lie. Plants and animals communicate with one another by sounds, ritualistic displays, colors, airborne chemicals and other methods, and biologists once naively assumed that the sole function of these communication systems was to transmit accurate information. But the more we have learned, the more obvious it has become that nonhuman species put a lot of effort into sending inaccurate messages.

...

... [But] our talent for dissembling dwarfs that of our nearest relatives by several orders of magnitude.