Researchers used population samples from the ALFRED database and the Human Genome Diversity Project (HGDP), in conjunction with 68 populations from the Ethnographic Atlas, in an attempt to identify specific genes involved in human adaptation to environmental stimuli as a result of migration. Specifically, researchers looked at the allele frequencies for four different genes typically associated with varying subsistence forms. These four included the APOE apolipoprotein E gene (lipid transport and regulation of cholesterol), LCT lactase gene (enzyme that decomposes lactose), CCR5 chemokine receptor gene (deletion mutation that decreases immunodeficiency virus propagation), and the ADH1B alcohol dehydrogenase gene (important enzyme for alcohol metabolism). The allele frequencies were then analyzed to distinguish any possible correlation to economic-culture types using a two-sided Spearman Test. Researchers also ran a similar test to analyze allele frequencies and pathogen load, however the majority of the findings were not statistically significant. The findings suggest that there is a definite relationship between the allele frequencies and type of economy of a population.