 Potential causes invoked in the discussion above include sampling of gametes, sampling of parents, founding of new populations, splitting of populations, each of which is intensified when populations are small, while potential effects mentioned include fluctuations of gene frequencies from one generation to the next, loss of variants from a population, and fixation of a (possibly non-adapted) type in a population. Are these causes and effects all drift? With that sort of confusing heterogeneity, there is little surprise that the concept has drawn philosophical attention. But at least we have our starting point for philosophical discussion (see Beatty 1992 and Plutynski 2007 for additional historical overview).