This is trivialising the issue. 3. address the lack of controls to regulate the pathway. From the point of view of embryogenesis, these anatomical systems are completely different from one another. Each modification constitutes a gift, a bequest from a primate family to its descendants. It is astonishing that these gifts should have developed simultaneously.
Some biologists speak of a predisposition of the genome.
The success of the scientific enterprise can often blind us to the astonishing fact that science works. Though it is usually taken for granted, it is both incredibly fortunate and deeply mysterious that we are able to fathom the workings of nature by use of the scientific method. The purpose of science is to uncover patterns and regularities in nature, but the raw data of observation rarely exhibit explicit regularities. To make progress in science we need to crack the cosmic code, to dig beneath the raw data, and uncover the hidden order. To return to the crossword analogy, the clues are highly cryptic, and require some considerable ingenuity to solve.