Final answer:
Differences between local human groups account for roughly 5-15% of the total genetic variation in humans, with the majority of genetic variation existing within individual populations.
Step-by-step explanation:
Differences between local human groups account for only a small percentage of the total genetic variation in humans. Genetic studies have shown that most of the variation (about 85-95%) exists within a single population, not between different populations or groups. This means that the total variation attributed to differences between local human groups is approximately 5-15%. The variability within a population includes differences in alleles, which are the various versions of genes present in individuals. These genetic differences can be observed in physical traits like skin pigmentation, which varies in response to exposure to UV radiation. In contrast, large differences in allele frequencies, such as the distribution of the IB and I alleles, could lead to significant evolutionary changes over time within populations.