A blob of cells
When talking about the way in which the human head and the human nervous system develops, Shubin creates a simple picture to help the reader understand how it slowly develops. He describes the head as being a blob of cells that develop slowly until they reach the most complex system. This portrayal helps the reader who may not know many things about complex anatomy understand how one of the most complex systems in the human body develops.
Like a cake recipe
In the sixth chapter, the author portrays the evolutionary process as being a cake recipe that was passed through generations from one person to another. The recipe suffered in time various modifications to the point where countless other recipes were created out of it. The image created here is a simple one and has the purpose of helping the reader understand how the evolutionary process took place and how it changed in time to the point where countless other species appeared.
What is a body
In the seventh chapter, the author takes time to portray a proper image about what it means to be a body. Many considered any lump of cells as being a body but according to Shubin, a body is a group of cells in which every cell has a defined function. Thus, humans and animals can be considered as being bodies but bacteria or just groups of cells are not called bodies.
Like a bridge
In the seventh chapter, Shubin compares the human skeleton to the frame of a bridge. The author talks about how a bridge is built in such a way as to withstand pressure and it was made for a particular purpose. The image of the bridge helps the reader understand how our skeleton developed as well to perform certain tasks and to be able to withhold certain forces.
