By definition, gene-culture co-evolution is reciprocal. Genes and culture are both in the driver’s seat. This point is crucial because there is a tendency to overreact to cultural determinism and to forget that culture does matter, even to the point of influencing the makeup of our gene pool. Through culture, humans have directed their own evolution.

Take the ability to digest lactose, commonly called milk sugar. Among early humans, only babies could digest it because only they made the enzyme that breaks it down. This enzyme was lost as one grew up, with the result that milk consumption would cause indigestion, abdominal gas, and diarrhea. This is still the case in humans from much of Africa and Asia.

Then some cultures began to domesticate cattle, initially for meat. In times of famine, they turned to milk, and those who could better tolerate it had better chances of survival. So there was now natural selection for individuals who could produce the necessary enzyme not only in childhood but in adulthood as well.

The resulting evolutionary change was both genetic and cultural. With more and more adults being able to digest milk, it became possible to develop various dairy products, like cheese, and use milk as an ingredient in a wide range of foods. It also became possible to select for cattle that produce more and better milk (Beja-Pereira et al., 2003). A new way of life developed and thus brought about even more selection for this enzyme.

In sum, a genetic change can open up new paths for culture to follow and thereby create new paths for genes to follow. But that isn’t all. The same situation can develop even when no genetic change has taken place, at least not initially. We see this, for instance, when a culture spreads out of one population and into another. The gene-culture interaction is new even though neither party to the interaction is new.

A fruitful encounter

One specific example is the encounter between Christianity and the guilt cultures of Northwest Europe, which differ from the shame cultures that prevail elsewhere. The difference is a major one. In a shame culture, your wrongdoings are punished only when witnessed by someone from your community. In a guilt culture, they are punished even when there is no witness, other than the one inside your head.

Guilt culture is commonly attributed to the Christian doctrine of original sin, and more specifically to the radicalization of this doctrine under Protestantism (see Note 1). Yet neither of these presumed causes really lines up with the presumed effect.

For one thing, it’s doubtful whether this doctrine was even known to early Christians in the Middle East. True, Paul did write that humans had lost their immortality because of Adam’s sin:

Therefore, just as through one man sin entered into the world, and death through sin, and so death spread to all men, because all sinned.Romans 5.12

This belief also appears in the Talmud, but it was never understood there as meaning that people are sinful because they inherit Adam’s burden of sin. The Jewish view, like the later Muslim one, has been that people are sinful because they are imperfect beings. This was probably also the view of early Christians. Even today, Eastern Christians reject the doctrine of original sin, preferring the term “ancestral sin”:

In the Orthodox Christian understanding, they explicitly deny that humanity inherited guilt from anyone. Rather, they maintain that we inherit our fallen nature. While humanity does bear the consequences of the original, or first, sin, humanity does not bear the personal guilt associated with this sin. (Original sin, 2014)

It was among Western Christians—Roman Catholics and, later, Protestants—that original sin developed into a doctrine. We see this in the writings of Irenaeus (2nd century) and Augustine (354-430), who identified the original sin as concupiscence, i.e., ardent, sensual longing. Protestantism is then said to have radicalized this doctrine, as seen in the Augsburg Confession of Lutheranism:

It is also taught among us that since the fall of Adam all men who are born according to the course of nature are conceived and born in sin. That is, all men are full of evil lust and inclinations from their mothers’ wombs and are unable by nature to have true fear of God and true faith in God. Moreover, this inborn sickness and hereditary sin is truly sin and condemns to the eternal wrath of God all those who are not born again through Baptism and the Holy Spirit.

But this radicalization was already under way before Protestantism. An English Catholic, Anselm of Canterbury (1033-1109), was the one who first separated original sin from concupiscence and defined it as “privation of the righteousness that every man ought to possess” (Original sin, 2014). Within Western Christendom, pre-Protestant England was likewise the epicenter of an intense penitential tradition that dated back at least to Anglo-Saxon times (Frantzen 1983). This tradition can be summed up as follows: “it is better to be shamed for one’s sins before one man (the confessor) in this life than to be shamed before God and before all angels and before all men and before all devils at the Last Judgement” (Godden, 1973). The English abbot Aelfric of Eynsham (955-1010) described the need to do penance for all shameful acts, even those that are witnessed solely by spirits of the dead:

He who cannot because of shame confess his faults to one man, then it must shame him before the heaven-dwellers and the earth-dwellers and the hell-dwellers, and the shame for him will be endless.(Bedingfield, 2002, p. 80)

Conclusion

As evidenced by the doctrine of original sin and the penitential tradition, Northwest European guilt culture was not a product of Christianity in general or of Protestantism in particular. It seems to have its origins in pre-existing tendencies that were absorbed into the new spiritual environment, much like the Christmas tree and other formerly pagan traditions. It thus grew steadily more important as the geocenter of Christianity moved steadily west and north.

This is not to belittle Christianity’s role. The new faith created ideological, social, and physical structures that were better at enforcing moral norms than anything beforehand. These norms may have had pagan antecedents, but they were now being enforced much more thoroughly.

We see this in the Medieval Synthesis that took hold from the 11th century onward, when Church and State joined forces to defend the Christian world: externally, through military campaigns against Muslims in the Iberian Peninsula, southern Italy, and the Middle East; and internally, through vigorous efforts to pacify social relations, either by increased use of capital punishment or by the Pax Dei—a Church-led movement to limit the scope of war in feudal society (Peace and Truce of God, 2014). Finally, guilt culture was strengthened through confession of one’s sins, particularly after this practice became mandatory with the Fourth Lateran Council (1215). All wrongdoings had to be atoned at least once a year, however private or personal they might be (Sacrament of Penance, 2014).

Medieval Christian culture favored the survival and reproduction of people who previously would not have survived and reproduced. Conversely, by criminalizing personal violence, particularly in cases where the offender felt no guilt or remorse, this culture was now eliminating people for behavior that had once been admired.

It is often believed that Europe took off from the 15th century onward, when it expanded into Africa, the Americas, and Asia. Actually, the takeoff began earlier, particularly during this period when Church and State teamed up to lay a new basis for social relations. It was this new moral order that enabled Europe to get ahead (Frost, 2012). As Thomas Hobbes (1588-1679) wrote, no advanced society can develop where men have no “other security than what their own strength and their own invention shall furnish them withal.”

In such condition there is no place for industry, because the fruit thereof is uncertain: and consequently no culture of the earth; no navigation, nor use of the commodities that may be imported by sea; no commodious building; no instruments of moving and removing such things as require much force; no knowledge of the face of the earth; no account of time; no arts; no letters; no society; and which is worst of all, continual fear, and danger of violent death; and the life of man, solitary, poor, nasty, brutish, and short. [The Leviathan, 13]