Kin selection without brains

One of the common misunderstandings of kin selection is that recognising relatives requires advanced cognition:

In passing it needs to be remarked that the epistemological problems presented by a lack of linguistic support for calculating, r, coefficients of relationship, amount to a serious defect in the theory of kin selection. Fractions are of very rare occurrence in the world’s languages, appearing in Indo-European and in the archaic civilizations of the Near and Far East, but they are generally lacking among the so-called primitive peoples. Hunters and gatherers generally do not have counting systems beyond one, two and three. I refrain from comment on the even greater problem of how animals are supposed to figure out how that r [ego, first cousins] = 1/8. The failure of sociobiologists to address this problem introduces a considerable mysticism in their theory.

- Sahlins (1977) The Use and Abuse of Biology: An Anthropological Critique of Sociobiology.

Please give me an example where kin selection has been conclusively demonstrated in any species other than animals. I'm not interested in theoretical speculations or models. I'm interested in actual evidence.

- Moran, Larry (2012) Squirrels, Dawkins, and Evolution

Er, kin selection is not confined to animals. See, for example:

• Gilbert, O. M., Strassmann, J.E., & Queller, D.C. (2012) High relatedness in a social amoebae: the role of kin discrimination.

• Kuzdzal-Fick, J.A., Fox, S.A., Strassmann, J.E. & Queller, D. C. (2011) High relatedness is necessary and sufficient to maintain multicellularity in Dictyostelium.

• Gilbert, O.M., Foster, K.R., Mehdiabadi, N.J., Strassmann, J.E., Queller, D.C.(2007) High relatedness maintains multicellular cooperation in a social amoeba by controlling cheater mutants.

• Donohue, K. (2003) The influence of neighbor relatedness on multilevel selection in the Great Lakes sea rocket.

• Kelly, J.K. (1996) Kin selection in the annual plant Impatiens capensis.

• Dudley, Susan A. and File, Amanda L. (2007) Kin recognition in an annual plant.

• Rumbaugh K.P., Trivedi U., Watters C., Burton-Chellew M.N., Diggle S.P., West S.A. (2012) Kin selection, quorum sensing and virulence in pathogenic bacteria.

• Strassmann, J.E., Gilbert, O.M., Queller, D.C. (2011) Kin discrimination and cooperation in microbes.

• Chao, L., Hanley, K.A., Burch, C.L., Dahlberg, C. and Turner, P.E. (2011) Kin selection and parasite evolution: higher and lower virulence with hard and soft selection.