Final answer:
Evolution, a key concept in biology, describes the process by which modern organisms have descended from ancient ancestors. This principle, central to a biology professor's curriculum, positions humans as part of a complex tree of life that started from lower, more primitive life forms. The evidence for evolution comes from various fields, including genetics and comparative anatomy.
Step-by-step explanation:
The concept that humans evolved from "lower" life forms is grounded in the scientific theory of evolution, a fundamental principle often discussed in biology courses led by a biology professor. Early theories of life's origin posited a static and unchanging nature or a simplistic hierarchy of beings, with humans placed above other forms of life. However, the work of Charles Darwin and others established evolution as the prevailing explanation for the diversity of life forms on Earth. Today, the evidence for evolution is overwhelming, showing that all living organisms, including bacteria and humans, share a common evolutionary history. This is visible in the cellular structures that are common across diverse forms of life. The notion of evolution owes much to the concept of natural selection, which suggests that species that are better adapted to their environment are more likely to survive and reproduce. Evolutionary biology continues to be a vibrant field, with new discoveries and observations regularly contributing to our understanding of life's history. Whether analyzing genetic information, such as mtDNA that traces human ancestry back to a common origin in Africa, or investigating other forms of life, biologists confirm that the diversity of life on Earth has evolved from a more primitive, or "lower" common ancestor.