El nacionalismo visto por la psicología evolutiva

El título del artículo de J. Philippe Rushton, "Ethnic nationalism, evolutionary psychology and Genetic Similarity Theory", recién publicado, no acaba de reflejar del todo su contenido, pues no se centra en el nacionalismo, pero es muy interesante para entender por qué tendemos a favrecer, por ejemplo, a los connacionales frente a los extranjeros. Éste es el resumen:

Genetic Similarity Theory extends Anthony D. Smith’s theory of ethno-symbolism by anchoring ethnic nepotism in the evolutionary psychology of altruism. Altruism toward kin and similar others evolved in order to help replicate shared genes. Since ethnic groups are repositories of shared genes, xenophobia is the ‘dark side’ of human altruism. A review of the literature demonstrates the pull of genetic similarity in dyads such as marriage partners and friendships, and even large groups, both national and international. The evidence that genes incline people to prefer others who are genetically similar to themselves comes from studies of social assortment, differential heritabilities, the comparison of identical and fraternal twins, blood tests, and family bereavements. DNA sequencing studies confirm some origin myths and disconfirm others; they also show that in comparison to the total genetic variance around the world, random co-ethnics are related to each other on the order of first cousins.

Es decir, que la inclinación a mostrar preferencia por nuestros "co-étnicos" (whatever that means) es perfectamente natural. Otra cosa es la exacerbación de ese sentimiento. Como dice Rushton:

The hypothesis presented here is that because fellow ethnics carry copies of the same genes, ethnic consciousness is rooted in the biology of altruism and mutual reciprocity. Thus ethnic nationalism, xenophobia and genocide can become the 'dark side' of altruism.

Sobre el "etno-simbolismo", puede verse esta introducción. Sobre la "Teoría de la Similitud Genética", este sintético wiki o, para nota, este artículo del propio Rushton. Una crítica a esta teoría, aqui.