They sound like they were written specifically to be a book. They are well integrated and don't feature the normal language one expects from lectures that are turned into books. This is a very good thing for those of us who like to read books as books and not as a collection of disjointed essays or oral ramblings converted to print. Lewontin highlights and emphasizes the combined factors of phenotype development. He criticizes the view that only genotype specifies phenotype.
Environment also plays a key role in the equation.
It is often as poetic as it is insightful. Lewontin causes the reader to look at nature and the living world through different lenses. He aptly points out how Darwin was the first to clearly demarcate between internal processes and external ones. Many metaphors have been invoked for this relation between independent environment and organism. The organism proposes and the environment disposes.