The central issue with the path that Darwin was following was assuming the species he had collected were all the same. He didn’t really study the origins of any single species instead focused on pigeons and geographic patterns of distribution. Darwin’s field was more religious rather than naturalist.
Weiner has the advantage of being able to compare and contrast Darwin and the Grant’s by building chapter three like a sandwich. The reason for Weiner’s strategy was to give expert testimony to back up the idea of evolution. He used research from different biologist in different times, and their statements supported each other.
Section one falls in the concrete and specific section of the abstraction ladder. The section mentions vivid sketches, and actual measurements. Section two would fall somewhere in the middle of the scale for the abstraction ladder because their evidence was based on their observations of behavior. Section three falls in the lower part of the ladder because measurements determine the finch’s survival. The analogy of the bowl of pistachio nuts is given so the reader can understand natural selection from their own experience when eating nuts. The finches that did not drop the seeds like the Magnitrotris are more likely to survive when times are hard their lives depend on them.
The explanation of why Weiner characterizes this chapter as “a special providence” was to describe to the reader how patiently the Grants waited for the rain to come so the finches would reproduce. Because most of the seeds had been eaten away by the finches, the finches were dying. After four years of drought, the Grant’s had determined that evolution would not be seen. After a long period of waiting, rain finally came down, giving life to the species on the island Daphne Major. Although not a single finch survived the variations of finches bodies and beaks were significant from one generation to the next. It’s called providence because rain finally came after the drought, like a gift from God, and that rain allowed the finches to reproduce.
The basic argument Weiner makes in this chapter is to show sexual selection can change due to natural selection. The studies of John Endler with the guppies also shows how changes in the environment cause natural selection of a species. These studies give examples of natural selection in a different species, but have comparable results to those of the finches.