Fig 1. Distribution of the number of low-risk loci (0 high-risk alleles) and loci with 1 or 2 high-risk alleles within the global population of the 1000 Genome Project [59].

The average number of loci carrying 0/(1 or 2) high-risk alleles was 16/16 and coincided with the median of this distribution. The relative position of the Altai Neanderthal and the Denisovan hominin high-coverage genomes are indicated, as well as the genome of the oldest available anatomically modern human, that of a 45,000 year old individual from Ust’-Ishim. Three SNPs (rs2292596, rs56318881, and rs9282861) analysed in this study were not covered by the 1000 Genome Project variant data and were therefore not included in this analysis. For each of the GSTM1 and GSTT1 loci in the ancient hominin genomes, being possibly homozygous or heterozygous low-risk (S2 Table), a contribution of 1 high-risk allele was conservatively counted in. Details in Section B in S1 Text.