The widespread availability of antiretroviral therapy may be fundamentally altering human evolution by removing the selective pressure that HIV-1 once exerted on our immune genes. This finding challenges assumptions about how modern medicine interacts with natural selection in real time. Research tracking maternal HLA-B genotypes in a South African cohort reveals that specific genetic variants historically provided significant survival advantages against HIV-1 infection. The HLA-B gene encodes proteins crucial for presenting viral fragments to immune cells, with certain alleles offering superior protection while others increased disease susceptibility. Before effective treatment became available, these genetic differences would have influenced reproductive success and population-level allele frequencies over generations. However, antiretroviral therapy has essentially neutralized these survival disparities. When viral loads are suppressed to undetectable levels through treatment, the protective advantage of beneficial HLA-B variants disappears, as does the disadvantage of susceptible variants. This represents one of the clearest documented examples of infectious disease driving human genetic diversity—and simultaneously shows how medical intervention can halt that evolutionary process. The implications extend beyond HIV research into fundamental questions about human adaptation. As global access to antiretroviral therapy expands, populations may retain genetic variants that would otherwise face negative selection. This could preserve genetic diversity that might prove valuable against future viral threats, but it also means that natural resistance mechanisms may not strengthen over time. The study provides rare real-world evidence of pathogen-driven selection in humans and demonstrates how rapidly modern medicine can interrupt evolutionary forces that have shaped our species for millennia.