Deceptive tricks in nonhuman primates can feel stunningly human. “The first time I saw an established leader lose face, the noise and passion of his reaction astonished me,” writes the celebrated primatologist Frans de Waal about chimpanzees in his 2019 book, Mama’s Last Hug. “The challenger barely stepped out of the way when the alpha countercharged…In the midst of such a confrontation, the alpha would … writhe on the ground, scream pitifully, and wait to be comforted by the rest of the group.” De Waal went on to say that the alpha acted much like a juvenile, making noisy tantrums and keeping an eye on who approached him. If he had supporters, he would continue to approach and confront his rival—a certain level of savviness that once was thought unimaginable for nonhuman primates to plot out and execute.
Indeed, the evolutionary rise of social intelligence (also known as Machiavellian intelligence) allows primates to advance personal interest by deceiving while avoiding being deceived. This fits well for our own human species, especially when power is at stake. A great example of this is often politicians, who are good at (and are well known for) this trick of trade in societies from the Roman Republic to modern nations, no matter whether they are democratic or despotic. This can lead many to wonder whether truth matters any more, and to consider a hard question: Why do we stick to truth in the first place if lies and deceptions can get us ahead in nature? The answer lies in the value of truth, which can be far higher than what it has often been credited for.
This becomes obvious when we take the perspective of nonhuman primates such as the Tibetan macaque, a species my colleague and I have studied in East China since the 1980s. Tibetan macaques live in small, hierarchical societies, each made of two to five dozen members. Adept in social skills, they resort to both cooperation (such as allying and aiding each other in physical conflict) and deception (scapegoating other group members for faults they have committed), as they see fit, to gain an advantage over their peers. As deceptive maneuvers are rewarded, truth has no value, and society is stuck in a Hobbesian state of “one against all and all against one.”
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The most important social event for a Tibetan macaque group is power succession among males. It is a periodical, violent affair when the alpha male is dethroned by mostly a former subordinate. To climb the hierarchy ladder, an underling may use grooming—that is, backscratching—as a manipulative tactic to build an alliance with a superior, especially the alpha. As the alpha has no shortage of bootlickers, he often rejects the “bribery” by driving would-be sycophants away. In response, a subordinate would then turn to Plan B: grabbing a male baby and using it as a buffer against the aggression from his superior. As babies are cared by all in the group, the alpha would be instantly appeased and accept the approach by the subordinate, and the two males begin to perform bridging, a quirky rite in which the alpha takes the infant’s legs belly up and sucks its penis while the subordinate holds the infant’s upper body. After the infant is released a little while later, the minion can now groom the alpha. Mission accomplished.
Cunning social maneuvers like using babies as tools for social aspirations are the means to an ultimate end: to contend for the crown by ousting the old king, which has been observed repeatedly during the four decades of our field work. One takeaway message for us is that social intelligence is a double-edged sword. It makes macaques and their primate brethren capable of brokering peace deals, fostering friendships, and building coalitions. Meanwhile, it also enables them to concoct sly schemes to exploit the benefits of teamwork for personal gains. In the end, however, what matters is who can outfox who within the group, regardless of prosocial cooperation or antisocial manipulation. This explains why, in the long run, social intercourse in clever primates such as macaques—as well as baboons and chimps—is a zero-sum game, and society as a whole stagnates.
We can get around this social trap by curbing cheating and promoting honesty. This is where humans excel and all other primates fall short. Protected by laws and encouraged by prosocial norms, we are liberated from concerns about being duped, incentivized to stick to the truth, and rewarded with the fruit of cooperation. Social interactions, therefore, become win-win for us, rather than zero-sum for macaques and their associates. Furthermore, truth, trust, and cooperation go hand in hand, leading to ever larger benefits as we pursue ambitious endeavors out of the common interests of our villages, cities, and nations.
As a result of our extensive, cross-tribal collaboration, which is a clear demarcation between all our primate relatives and us, human society thrives, and civilization marches on. Science and technology, for example, are among the distinct outcomes of such large-scale, institutionalized cooperation through finding, amassing, and applying objective truths. Otherwise, we wouldn’t have modern marvels such as rockets, computers, and antibiotics. Here, as we can see, the value of truth is, well, invaluable.
As a biological species, humans are by no means free from or immune to cheating as a product of evolution. Disinformation, for instance, may at times enjoy tangible success as its peddlers spin and profit from it. Nevertheless, despite the prevalence of frauds and falsehoods, especially in this digital age, we still hold dear truth and trust because they are the foundation for the enormous upside of cooperation. Without truth, it is impossible for humans to construct something like St. Peter’s Basilica, prevail in a significant conflict, or keep a functioning democracy. That’s why great numbers of people are honest and trustworthy, refusing to take advantage of others by cheating even when given the chance to profit from it. That’s why we combat antisocial lies and malicious deceptions, keeping them at bay. That’s why we can pin our faith on the ability of our species to find solutions to global concerns and challenges—poverty, peace, climate change—that require the cooperation on the largest scale.