⁶(de Catanzaro, 1991). However, see (Nowak et al., 2010) for a criticism of the centrality of kinship in the inclusive fitness theory. Related work on suicide and self, but without the evolutionary interpretation, is by Baumeister (1990). Taking the logic of inclusive fitness even further, one may be tempted to think of natural selection working on the level of groups of organisms (families, tribes, herds, etc.), so that it is the fittest group, not organism, that survives the selection. However, any theories based on such “group selection” are controversial, and it is not clear if it actually happens in nature. Some mathematical theories propose that natural selection on the level of individuals leads to emergence of phenomena which look just like the selection happened on the level of groups. In fact, according to the mathematical model by Hadany et al. (2006), something like self-destruction could actually emerge from purely individual-level selection, in cases when an individual organism finds the current environment particularly adverse.