Just how do you define "indigenous knowledge"? Perhaps in an African branch of botany?
And why would indigenous knowledge contradict evolution by natural selection?
Yes, it is true that aspirin was extracted from tree bark and digitalis from a plant called
foxglove. Yes, it could be the knowledge of plants and their medicinal value, although 
the traditional non-standardized dosage may hinder its modern acceptance. 
Yet I do not see anything similar in the physical sciences, engineering, economics or even literature.
But am willing to learn more, if anyone could offer explanations.
Otherwise I agree with a lot of points made by the author.