Final answer:
Evidence of genetic interconnectedness among human populations includes common ancestors originating from Africa, the study of human parasites such as lice that reveals coevolution, and gene flow illustrated by genetic mingling with other human species and adaptations like those found in the Tibetan population.
Step-by-step explanation:
There is substantial evidence showing that human populations are not genetically isolated from one another. Genetic studies of mitochondrial DNA (mtDNA) have identified common human ancestors from Africa around 200,000 years ago, suggesting a shared genetic heritage. Additionally, studies on human parasites, such as lice, provide evidence of coevolution that fills in gaps of the human evolutionary story. Furthermore, the analysis of gene flow and human migration patterns illustrates that cultural exchanges and interbreeding, even with other human species such as Neanderthals and Denisovans, have resulted in genetic mingling. The Tibetan population's adaptation to high altitudes via genetic mutations demonstrates rapid genetic changes within populations due to environmental pressures. Overall, studies clearly show that genetic variation within any single population is much greater than differences between populations, guiding us away from the notion of strict racial categories and toward a better understanding of human genetic interconnectedness.