Op-Ed: What humans and prairie voles have in common — a tendency to divide the world into Us and Them


Sometimes, even the most inspirational among us share some disheartening traits with other animals.

Humans have a remarkable capacity for empathy and compassion. We help strangers a continent away, donate anonymously, bequeath money to help people who will be born after our deaths. We can even choose to make the ultimate sacrifice in helping others — just think of the West African nurses who died fighting Ebola. These admirable traits owe little to Sunday morning sermons, the rule of law or pillows embroidered with the Golden Rule. Instead, they’re how we’re wired; we see the rudiments in other species. Such behaviors are rooted in our common ancestry.

Among chimps, for example, suppose some low-ranking member of a troop is mauled by an alpha-male. Afterward, the innocent bystander is more likely than usual to be groomed by other group members. But such “consolation” behavior isn’t generic — if the pummeled loser wasn’t a hapless victim, and instead was the fool who started the fight, no extra grooming for him.


Even rodents exhibit the building blocks of empathy. If a mouse observes another mouse in pain, its own pain threshold lowers. If a prairie vole has been stressed, it is more likely to be groomed. Rats will “work” (that is, repeatedly press a lever) to release another rat from a tightly enclosed space, and will even forgo a reward (chocolate!) in the process.

Wow, a lot like humans. And just as in humans, empathy tends to come with a catch.

Empathy tends to come with a catch.

Chimps console innocent victims only in their own group. A vole grooms a distressed individual only if it is his or her mate; a stressed stranger is out of luck. Pain thresholds lower in mice only if the mouse in pain is a mouse they know. Rats work to free another rat only if the latter is a cage mate or a rat of their genetic strain (roughly equivalent to breed in dogs). In other words, these species divide the world into Us and Them, and care much more about the former than the latter.

So do we. When people watch a video of a hand being poked with a sharp needle, they have an “isomorphic sensorimotor” response, unconsciously clenching their own hands, with sensory neurons activating as if they were experiencing the poke. But this doesn’t happen as much if the hand being poked is of another skin color.

In another study, researchers feigned an injury at a soccer stadium during a game — they were more likely to be helped if wearing home team regalia. Subjects considering the plight of an AIDS patient activate the anterior cingulate, a brain region implicated in feeling empathy — but only if the patient was infected with HIV from a blood transfusion, rather than from drug use. We come with implicit categories influencing whose plight moves us.

What’s demoralizing is when we see this play out in the behavior of moral giants.

Consider John Newton, a theologian who late in life became central to the banning of slavery in the British Empire. Remarkably, as a young man, Newton was the captain of a slave ship. When he had a religious epiphany (something he celebrated in the hymn he penned, “Amazing Grace”), he traded his captain’s role for the ministry. But there’s an inconvenient pause in Newton’s journey from slaver to abolitionist. As a newly minted preacher caring for the poor of London, he invested in and profited from the slave trade. Apparently, it wasn’t immediately obvious that everyone deserved God’s grace equally.

Then there’s Zenji Abe, who lead a squadron of Japanese planes that attacked Pearl Harbor in 1941. Years later, as an old man, Abe came to a memorial service in Hawaii, to apologize to elderly American survivors. Yet Abe had also participated in the Japanese invasion of China and the Rape of Nanking; there is no evidence that he ever apologized for that. Apparently, some types of ex-enemies count more than others.

And there’s Woodrow Wilson who, after the end of World War I, championed self-determination and human rights for subjugated European minorities. Yet Wilson’s legacy is tainted with racism. As president of Princeton University, he labored to reduce the number of African Americans admitted; as president of the United States, he instituted or reinforced segregationist laws. Moreover, he repeatedly invaded Latin American countries, overthrowing popularly supported governments to install puppets. Apparently, self-determination and civil rights applied only to people of some skin colors.


Which brings us to a current example. Consider Aung San Suu Kyi, the Nobel Peace Prize winner who spent 15 years under house arrest in Myanmar for nonviolently opposing its military dictatorship. Now, “Mother Suu” is the de facto leader of Myanmar. The news has been filled with reports of the ethnic cleansing of the Rohingya, the Muslim minority in Myanmar, following attacks by Rohingyan insurgents on government border posts. There has been a bloodbath of killings and rapes; Rohingya villages have been burned to the ground by the military and Buddhist mobs. Four hundred thousand Rohingya have fled into Bangladesh under the direst of circumstances.

And the response of Suu Kyi, who is a member of the country’s Buddhist aristocracy? At first, a yawning silence. Finally, on Tuesday, she addressed the crisis publicly. She praised her marauding military for its supposed restraint in pursing “terrorists,” aligning herself with some of the same generals who imprisoned her. She denied the long-standing persecution of the Rohingya and the scorched-earth campaign against them. She called for investigations into “what the real problems are” behind the exodus of the 400,000.

And thus Suu Kyi, a prisoner of conscience who suffered deeply to help free her people, shows that only some citizens of Myanmar count as “her people.” Or even as people.

Of course, humans and other animals aren’t identical in how they extend empathy to only the right kinds of sufferers. When a rat fails to aid an unfamiliar rat in need, it could offer an easy explanation — “that rat smells weird.” But when humans do it, we gussy up savage indifference with rationalization, denial, distortion and lies.

Ah, the progress we’ve made.

Stanford University neuroscientist Robert M. Sapolsky is the author, most recently, of “Behave: The Biology of Humans at Our Best and Worst.”

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