In Heroes and Cowards: The Social Face of War (Princeton University Press), Dora L. Costa and Matthew E. Kahn report that military units were more cohesive if they were composed of men who looked, voted, and worshiped like one another. Diverse units, meanwhile, did not fare as well.
All else equal, soldiers were less likely to desert if they were born in the United States or Germany than if they were born in Ireland, England, or elsewhere. Soldiers were less likely to desert if they were literate and had high incomes.
Holding all of the individual traits constant, white soldiers were less likely to desert if they fought alongside soldiers who were similar to them in terms of occupation, region, ethnicity, and religion. In African-American companies, soldiers were less likely to desert if they fought alongside soldiers from the same region.
But the two economists insist that on its own terms, their Civil War study tells a powerful story: Social networks matter. In a forthcoming paper in the journal Demography, they report that in Union veteransâ€™ old age, their health was worse if they had experienced a high amount of battle stress during the war. That isnâ€™t surprising. The paperâ€™s startling finding is that among veterans whose military companies had been highly cohesive, the effect disappeared.
In a previous paper on economic diversity and community life, Ms. Costa and Mr. Kahn criticized the political scientist Robert D. Putnamâ€™s much-debated 2000 book, Bowling Alone: The Collapse and Revival of American Community. Mr. Putnam, they said, had exaggerated the decline of American civic life and had looked in the wrong places for explanations. According to Ms. Costa and Mr. Kahn, we shouldnâ€™t blame television or overwork or urban design. The real explanation is the rise in social heterogeneity, which makes people slower to form bonds of trust.
This should surprise no one.
To act together, we need to know that others will back us up for standing up for abstract values — basically, that there’s consensus on those values.
Consensus comes best from those of the same culture, language, background and, yes, those whose ancestors went through the same evolutionary process that shaped their consciousness.
We don’t create ourselves. We are not blank slates. We are what we are, biologically, and evolution is written all over us. It’s ignorant and comical to deny it.