Science on Religion

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Out-group cooperation

Teamwork handsPeople evolved to be tribal. Insiders are given the benefit of the doubt and are trusted, while outsiders are shunned, discriminated against, and ideally avoided altogether. At least, this is the picture modern evolutionary theory paints of human evolution. However, economists Xiaofei Sophia Pan (Harvard University) and Daniel Houser (George Mason University) challenge this monolithic picture. They argue that in-group favoritism and out-group discrimination only occur when a group has independent sufficiency; if a group needs cooperation to survive, it will not discriminate against out-groups.

Put another way, the extent of cooperation needed for economic production or survival directly affects whether a group will develop anti-out-group tendencies. More cooperation with out-groups reduces the chances of mistrusting them. This correlation between cooperation and acceptance of out-groups can go in two directions. First, one could argue that more open societies have a higher chance of cooperating. Alternatively, one could argue that in-group exchange increases the chances of in-group favoritism and thereby also of out-group discrimination. The authors favor the first theory: all groups will exhibit in-group favoritism, but this does not necessitate out-group prejudice.

To test their theory, the researchers divided 202 subjects into 14 sessions, in which each session had two small groups of equal size placed in separate rooms. One group would require cooperative production while the other experienced independent production. Both groups had a geometric puzzle to solve, and the fastest group received financial compensation. This gave everyone an economic motive to work independently. The cooperation production group faced a puzzle that few could solve on their own, and so the group had to work collectively in order for everyone to complete their puzzle. By contrast, the independent production group had a comparatively easy puzzle that most could solve by working on their own.

After finishing the puzzle, the participants took on the role (determined randomly) of investor or trustee. The investor chooses whether or not to trust the trustee while the trustee simultaneously chooses whether to join or defect from the investor. Both parties knew whether the other belonged to the same in-group or to a foreign out-group. Finally, after this task was completed, investors noted whether they expected the trustee to join or defect.

As expected, the cooperative production group cooperated more in solving its puzzles than the independent production group. More importantly, cooperative production group investors both trusted out-group trustees and expected out-group trustees to reciprocate this trust more than independent production group investors. Cooperative production investors and independent production investors alike favored their own in-group, but the former, unlike the latter, displayed the same rate of trust for in-group and out-group trustees (whereas the latter discriminated against out-group trustees). Lastly, cooperative production investors continued to trust out-group trustees, even if previous trustees from that out-group elected to betray this trust.

If the researchers are correct, then human evolution is not as simple as “in-group favoritism at the expense of trusting out-groups is adaptive.” It appears that cultures that depend on cooperation are more willing to trust outsiders, and will continue to trust them despite betrayals. Of course, without a time machine, one cannot confirm this with a strong degree of certainty, but, the researchers being American professors, at least Americans can trust their results.

For more, see “Cooperation during cultural group formation promotes trust towards members of out-groups” in the Proceedings of the Royal Society B.


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