A few days ago we pub­lished the first and sec­ond install­ments of this Peace Among Pri­mates series, by neu­ro­sci­en­tist Robert Sapol­sky. Today we pub­lish the third and final one.

Peace Among Pri­mates (Part 3)

Any­one who says peace is not part of human nature knows too lit­tle about pri­mates, includ­ing ourselves.

–By Robert M. Sapolsky

Nat­ural born killers?

Are there any lessons to be learned here that can be applied to human-on-human vio­lence apart, that is, from the pos­si­ble desir­abil­ity of giv­ing fatal cases of tuber­cu­lo­sis to aggres­sive peo­ple? Can human behav­ior be as mal­leable and as peace­ful as For­est Troops?

Any bio­log­i­cal anthro­pol­o­gist opin­ing about human behav­ior is required by long-established tra­di­tion to note that for 99 per­cent of human his­tory, humans lived in small, sta­ble bands of related hunter-gatherers. Game the­o­rists have shown that a small, cohe­sive group is the per­fect set­ting for the emer­gence of coop­er­a­tion: The iden­ti­ties of the other par­tic­i­pants are known, there are oppor­tu­ni­ties to play games together repeat­edly (and thus the abil­ity to pun­ish cheaters), and there is open-book play (play­ers can acquire rep­u­ta­tions). And so, those hunter-gatherer bands were highly egal­i­tar­ian. Empir­i­cal and exper­i­men­tal data have also shown the coop­er­a­tive advan­tages of small groups at the oppo­site human extreme, namely in the cor­po­rate world.

But the lack of vio­lence within small groups can come at a heavy price. Small homoge­nous groups with shared val­ues can be a night­mare of con­for­mity. They can also be dan­ger­ous for out­siders. Uncon­sciously emu­lat­ing the mur­der­ous bor­der patrols of closely related male chimps, mil­i­taries through­out his­tory have sought to form small, sta­ble units; incul­cate them with rit­u­als of pseudokin­ship; and thereby pro­duce effi­cient, coop­er­a­tive killing machines.

Is it pos­si­ble to achieve the coop­er­a­tive advan­tages of a small group with­out hav­ing the group reflex­ively view out­siders as the Other? One often encoun­ters pes­simism in response to this ques­tion, based on the notion that humans, as pri­mates, are hard-wired for xeno­pho­bia. Some brain-imaging stud­ies have appeared to sup­port this view in a par­tic­u­larly dis­cour­ag­ing way. There is a struc­ture deep inside the brain called the amyg­dala, which plays a key role in fear and aggres­sion, and exper­i­ments have shown that when sub­jects are pre­sented with a face of some­one from a dif­fer­ent race, the amyg­dala gets meta­bol­i­cally active aroused, alert, ready for action. This hap­pens even when the face is pre­sented sub­lim­i­nally, which is to say, so rapidly that the sub­ject does not con­sciously see it.

More recent stud­ies, how­ever, should mit­i­gate this pes­simism. Test a per­son who has a lot of expe­ri­ence with peo­ple of dif­fer­ent races, and the amyg­dala does not acti­vate. Or, as in a won­der­ful exper­i­ment by Susan Fiske, of Prince­ton Uni­ver­sity, sub­tly bias the sub­ject before­hand to think of peo­ple as indi­vid­u­als rather than as mem­bers of a group, and the amyg­dala does not budge. Humans may be hard-wired to get edgy around the Other, but our views on who falls into that cat­e­gory are decid­edly malleable.

In the early 1960s, a ris­ing star of pri­ma­tol­ogy, Irven DeVore of Har­vard Uni­ver­sity, pub­lished the first gen­eral overview of the sub­ject. Dis­cussing his own spe­cialty, savanna baboons, he wrote that they “have acquired an aggres­sive tem­pera­ment as a defense against preda­tors, and aggres­sive­ness can­not be turned on and off like a faucet. It is an inte­gral part of the mon­keys per­son­al­i­ties, so deeply rooted that it makes them poten­tial aggres­sors in every sit­u­a­tion.  Thus the savanna baboon became, lit­er­ally, a text­book exam­ple of life in an aggres­sive, highly strat­i­fied, male-dominated soci­ety. Yet in my obser­va­tion of For­est Troop, I saw mem­bers of that same species demon­strate enough behav­ioral plas­tic­ity to trans­form their soci­ety into a baboon utopia.

The first half of the twen­ti­eth cen­tury was drenched in the blood spilled by Ger­man and Japan­ese aggres­sion, yet only a few decades later it is hard to think of two coun­tries more pacific. Swe­den spent the 17th cen­tury ram­pag­ing through Europe, yet it is now an icon of nur­tur­ing tran­quil­ity. Humans have invented the small nomadic band and the con­ti­nen­tal megas­tate, and have demon­strated a flex­i­bil­ity whereby uprooted descen­dants of the for­mer can func­tion effec­tively in the lat­ter. We lack the type of phys­i­ol­ogy or anatomy that in other mam­mals deter­mine their mat­ing sys­tem, and have come up with soci­eties based on monogamy, polyg­yny, and polyandry. And we have fash­ioned some reli­gions in which vio­lent acts are the entrance to par­adise and other reli­gions in which the same acts con­sign one to hell. Is a world of peace­fully coex­ist­ing human For­est Troops pos­si­ble? Any­one who says, “No, it is beyond our nature, knows too lit­tle about pri­mates, includ­ing ourselves.

– Robert M. Sapol­sky, Ph.D., is the John A. and Cyn­thia Fry Gunn Pro­fes­sor of Bio­log­i­cal Sci­ences and a pro­fes­sor of neu­rol­ogy and neu­ro­log­i­cal sci­ences at Stan­ford Uni­ver­sity. He wrote the clas­sic Why Zebras Don’t Get Ulcers: An Updated Guide to Stress, Stress Related Dis­eases and Cop­ing. His most recent book is Mon­key­luv: And Other Essays on Our Lives as Ani­mals. A longer ver­sion of this essay appeared in For­eign Affairs. We bring you this post thanks to our col­lab­o­ra­tion with Greater Good Mag­a­zine, a UC-Berkeley-based quar­terly mag­a­zine that high­lights ground break­ing sci­en­tific research into the roots of com­pas­sion and altruism.

Be Socia­ble, Share!

•