A number of previous studies showed that heterozygosity declines with the increase in the geographic distance of human populations from East Africa. This relationship was also manifested in the observed higher number of polymorphisms in African compared to non-African populations. The cause for these trends was attributed to the effect of genetic drift resulting from serial bottlenecks (or founder effects) occurred during the range expansion of human populations. Although these studies reported about the quantitative difference in the number of polymorphisms, the effects of drift on the patterns of nucleotide change is unclear. Using large-scale data from whole genome and SNP array we show significant difference in the types of nucleotide change between global populations. We observed a much higher of AT to GC changes in African compared to non-African populations. Furthermore the magnitude of this difference negatively correlates with the geographic distance of the populations from East Africa. These results could be explained based on the combined effects of biased gene conversion and genetic drift.