Final answer:
Anthropologists study human biological variation by observing shifts in gene frequencies known as clines, which represent gradual geographic variations that occur across populations. Genetic anthropology and population genetics use molecular science to trace human origins, migrations, and genetic diversity.
Step-by-step explanation:
Anthropologists study human biological variation by observing gradual shifts in gene frequencies between neighboring populations; these shifts are known as clines. A cline refers to gradual geographic variation across an ecological gradient and embodies the concept that not all populations are genetically identical. The spread of humankind across the globe has resulted in divergence in the genetic characteristics of populations, which includes differences in stature, facial features, skin, hair, and eye color, as well as other genetic differences like those found in blood-group antigens. One branch of biological anthropology, genetic anthropology, uses molecular science to explore significant questions concerning human origins and migrations, plus the historical appearance of diseases. This field draws heavily on the study of population genetics, which focuses on microevolution through the measurement of changing allele frequencies within populations over time. Population genetics highlights how natural selection, genetic drift, gene flow, mutation, nonrandom mating, and environmental variances contribute to human biological diversity. The gene flow is particularly noteworthy, as it brings diverse alleles into new environments through migration. Cultural impacts, such as migration patterns and rules of sexual selection, affect the frequency of gene alleles in a population. Population genetics and anthropological studies help us understand the evolving nature of human populations and the complex interplay of evolutionary forces shaping our genetic makeup.