“There’s a counterintuitive motivation not to detect lies, or we would have become much better at it,” said Angela Crossman, an assistant professor of psychology at the John Jay College of Criminal Justice. “But you may not really want to know that the dinner you just cooked stinks, or even that your spouse is cheating on you.”

Image Credit... Toni Angermayer/Photo Researchers

The natural world is rife with humbug and fish tales, of things not being what they seem. Harmless viceroy butterflies mimic toxic monarch butterflies, parent birds draw predators away from the nest by feigning a broken wing, angler fish lure prey with appendages that wiggle like worms.

Biologists distinguish between such cases of innate or automatic deception, however, and so-called tactical deception, the use of a normal behavior in a novel situation, with the express purpose of misleading an observer. Tactical deception requires considerable behavioral suppleness, which is why it’s most often observed in the brainiest animals.

Great apes, for example, make great fakers. Frans B. M. de Waal, a professor at the Yerkes National Primate Research Center and Emory University, said chimpanzees or orangutans in captivity sometimes tried to lure human strangers over to their enclosure by holding out a piece of straw while putting on their friendliest face.

“People think, Oh, he likes me, and they approach,” Dr. de Waal said. “And before you know it, the ape has grabbed their ankle and is closing in for the bite. It’s a very dangerous situation.”

Apes wouldn’t try this on their own kind. “They know each other too well to get away with it,” Dr. de Waal said. “Holding out a straw with a sweet face is such a cheap trick, only a naïve human would fall for it.”

Apes do try to deceive one another. Chimpanzees grin when they’re nervous, and when rival adult males approach each other, they sometimes take a moment to turn away and close their grins with their hands. Similarly, should a young male be courting a female and spot the alpha male nearby, the subordinate chimpanzee will instantly try to cloak his amorous intentions by dropping his hands over his erection.