An Evolutionary Look at Jewish Religious Practice


Last November SIJS hosted a one-of-a-kind conference in conjunction with the Binah Yitzrit Foundation of Austin Texas.  The theme of the conference was Judaism in Evolutionary Perspective.  To some, a dialogue between Judaism and evolutionary theory seemed like shatnez. * To most of the nearly 150 participants, the papers presented touched them on a very intuitive level.  In truth, the evolutionary study of religious beliefs and practice has spawned a great deal of research in the last two decades.  However, the studies, with a few notable exceptions, focus on Christian practice and theology.  There is a veritable dearth of studies in the literature that directly addresses Jewish religious practice in evolutionary perspective.

For those who are skeptical, the model presented of the evolutionary study of religious practice is threefold.  It draws on ideas and theories that evolve from biological findings as well as theories that grew out of classic social psychology.  The two biological theories include the “Nature of Reciprocal Altruism” as explained by Robert Trivers (Trivers, R. L. (1971). “The Evolution of Reciprocal Altruism”. The Quarterly Review of Biology 46 (1): 35–57) and “The Costly Signal” or “Handicap Theory” of Amotz Zahavi (Zahavi, Amotz (1975). “Mate selection-A selection for a Handicap”,  J. theor. Biol 53: 205–214).

Trivers’ theory states that biological beings evolved in a way that selected for altruistic traits.  To some this takes the altruism out of altruism.  If an organism gains by a behavior how can it be altruistic?  The example of Torah Lishma, Torah Study for the Sake of Study, will help us understand this distinction.

If one studies Torah simply for the sake of studying Torah, then we would expect no reward for this study.  However, most midrashic sources do tie Torah Lishma to an ultimate reward in the after life.  Paradox?  If it is Lishma (“for its own sake”) then there is no reward.  If there is a reward then it’s not lishma.  I do not intend to propose a solution to the paradox.  Rather, I propose that altruism need not be wholly altruistic in order to be considered altruism just as Torah Lishma is not wholly Lishma.

Trivers defines altruistic behaviors as “those that benefit other organisms not closely related, while being apparently detrimental to the organism performing the behavior, benefit and detriment being defined in terms of [evolutionary] fitness.”  If I do it for my kin, I benefit by increasing the number of my genes in the future genetic pool.  Trivers uses a number of examples to explain the theory:  Warning cries of birds and blood sharing of bats.  In all of these instances, one organism sacrifices important resources in order for another to survive.  Birds will warn the flock of a predator’s presence despite increasing the likelihood of being caught.  Bats will share blood from the hunt with sick bats, endangering their own survival for lack of food.  In fact, if a sick bat doesn’t return the favor in the future, he will not be offered blood next time he is sick, being labeled as a cheater.  (The ability to identify cheaters is another fascinating area in the field of evolutionary psychology.)

Researches have taken the biological tendency to reciprocal altruism to be the biological basis of human charity, community wide “good deeds” (gemilut hasadim) and forgiveness.  Sacrificing our resources of time, energy and money for members of our religious group is not only a learned behavior. It has been selected by evolutionary forces.  It is adaptive in a world ever-evolving for humans to be charitable and forgiving.

The second biological concept adapted to human evolution is the “Costly Signaling Theory” described by Amotz Zahavi.  In order to signal genetic worthiness and invite reproductive opportunities, Zahavi says, an organism must encumber itself with characteristics that will at once draw the attention of its potential reproductive partners and signal biological fitness.  Two outstanding examples are the peacock’s tail and the reindeer’s antlers.

It seems to be a waste of evolutionary resources and a self-endangering characteristic for a peacock to grow a tail that, on the one hand, is so colorful, but on the other hand, is so heavy.  The weight of the tail is an impediment to survival to the degree that its bearer would have a harder time in either flight or fight.

The reindeer’s heavy antlers provide a similar handicap.  The antlers’ weight and bulkiness make it difficult to maneuver in the wild.  The male that can afford either the antlers or the plumage signals that despite the costliness of the attribute they are still fit to survive.  Indeed, the fitness could be in direct relation to the size of the antlers or the beauty of the tail.  It is a signal to females of the species that says, “I am a worthy mate and your offspring will be strong, like I am.”

These traits function like human “conspicuous consumption,” signaling the ability to afford to squander a resource simply by squandering it.  Receivers know that the signal indicates quality because inferior quality signalers cannot afford to produce such wastefully extravagant signals.

Extravagant Jewish religious signals, those that incur a great cost to the bearers are often thought to be religious items such astefilin, lulavim, shmura matza among others.  The extravagance Jews go to in order to hold a Seder on Passover or meals on other holidays signals those individuals’ worth to the community.  Coupled with acts of kindness and charity, those who signal loudest will be rewarded with the most important social currency: honor.  Those most honored will in turn be most sought after for opinions or to marry off their children.

Finally, when we add Leon Festinger’s (Festinger, L. (1957). A theory of cognitive dissonance. Evanston, IL: Row, Peterson)  “Theory of Cognitive Dissonance” to the mix, we can gain a greater insight into why people do what they do for the greater good; that is, for their “people” and for God.

The theory states succinctly “if a person is induced to do or say something which is contrary to his private opinion, there will be a tendency for him to change his opinion so as to bring it into correspondence with what he has done or said.”

Individuals tend to be internally honest – not wanting to lie to themselves.  As such, there will be intra-personal pressure to ensure that meals taken at home, prayer recited at home, candles lit in private are within the bounds of religious observance – even in the absence of a policing community.  So why do any of these “costly” procedures at home when I have no reason to believe that anyone will check.

Because I check.  And I am honest.  It would be too hard to conform to certain expectations if I did not buy into them.  And, once I do behave a certain way I have actually convinced myself that this is the best way to behave.  I behave therefore I believe.  This belief in turn leads to more behaviors until, finally, I am prepared to perform rituals even when I am alone.

To some, this model may seem cynical.  People do good deeds, pray and give charity for many other reasons, not just to marry off their children.  There is a tendency by us humans to overlook the biological contributions to our behaviors.  However, the lectures at the conferences reminded us that we are indeed biological beings.  We approach burial rites and their accompanying spirits in ways similar to groups of less developed countries.  Those who observe the laws of family purity tend to have more kids than those who do not.  Certain chimps exhibit quite human-like behaviors, and our evolutionary line, drawn some 5000 years ago which traces the generations from Adam to Noah to Abraham, looks an awful lot like the evolutionary tree, that spans 50,000,000 years Darwin drew only 100 years ago.

In order to understand the underpinnings we have initiated a fellowship program at Schechter in cooperation with the Binah Yiztrit Foundation that will engage in and promote research in the field of the evolutionary understanding of Jewish religious practice.

We are not saying that biological motives are the only ones.  But we must not overlook them if we want to truly gain a fuller understanding of human nature.


Rabbi Dr. Paul Shrell-Fox is a lecturer in Family and Community Studies and Academic Advisor for the Family and Community Studies and Women and Jewish Studies M.A. tracks at the Schechter Institute. He is a graduate of the Schechter Rabbinical Seminary and a practicing psychologist in Jerusalem.

* The prohibition in Jewish law  that prohibits the wearing of a fabric containing both wool and linen.

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