We also looked at how this long-term separation, isolation, and low effective population size affected the patterns of genetic variation in the Kalash. One striking example is the frequency of the derived allele for rs4988235, which has been linked to lactose tolerance. The Kalash, like the MA-1, are fixed for the ancestral allele for this variant, whereas their neighbors in Pakistan have been observed to have moderate frequencies of the derived allele. Although this supports their long-term isolation, it is surprising in other ways because the Kalash have no reported lactose intolerance and indeed celebrate a “milk day” during their annual spring rituals.38 This suggests that there might be additional derived lactase-persistence alleles in the LCT-MCM6 (MIM: 601806) region in this population.