How is the scientific method applied to the evolution of man?

Evolution was recognized as a fact before Darwin was born.

Geologists in the 18th century looking at deep layers in the earth realized that at earlier times the distribution of flora and fauna was radically different from anything seen today: trilobites in older layers, then they're all gone. Dinosaurs in later layers, then they're all gone. Flowers only appear in more recent layers. No primates in the older layers. Etc, etc. etc.

Clearly, the distribution of species on earth was changing over time. That's evolution.

Darwin?s THEORY of evolution (more specifically, his concept of natural selection) provided a simple and compelling explanation for facts that were long known. Since then that basic theory of natural selection has been augmented by knowledge about DNA, etc., but nothing has replaced it as our basic explanation of how successive generations change over time.

Originally evolution based its facts on very carefully gleaned information from observing nature. Darwin saw how his finches differed from each other, and then he established a framework for how that might have come to be. The same pattern occurred predictably with many other species. The fossil record then showed the same types of relationships as Darwin described for living beings