Final answer:
The central unifying theory of biological anthropology is evolutionary theory, which includes the key concept of natural selection and provides the foundational framework for understanding human evolution and biological diversity.
Step-by-step explanation:
The central unifying theory of biological anthropology is evolutionary theory. Underpinning this theory is the concept of natural selection, as proposed by Charles Darwin, which suggests that organisms with traits that are favorable for their survival and reproduction are more likely to pass on these advantageous traits to the next generation. This concept is crucial for understanding the biological evolution of humans, the diversity of human traits, and the adaptation of humans to various environments over time. Evolutionary theory is the framework biologists and anthropologists use to explore and predict biological diversity and evolution. Notably, Theodosius Dobzhansky famously stated, "nothing makes sense in biology except in the light of evolution." This highlights the theory's significant role as the foundational principle from which we understand the progression of life on Earth, including the sociocultural and biological development of human beings.