In chapter 6, Richard Dawkins talks about the origin of life on earth and about miracles. It is believed that a planet is originated from compound gas. Now the chance of compound gas to form self replicating molecule which will then give rise to life form on the planet is very improbable mathematically but it’s probability is non zero even if chance is very low. It is thus a miracle. A miracle is assumed to be impossible but in mathematics it is an highly improbable event but with non zero probability.
In Chapter 7, Dawkins talks about constructive evolution.
It is known that natural selection is destructive in nature( removes bad things from environment) and mutation is constructive in nature(adds thing to create new possibility). Together these two compromise evolution. Constructive Evolution is contributed by two processes :- Coadapted genotype( coevolution ) and Arm races. In coadapted genotype , genes adapt themselves in a cooperative manner rather than in individual manner. Environment to genes is genes themselves . So they coevolve according to their environment.
Armraces is a process in which several species compete . Factors of arm races are enemies, climate and dynamic environment. There are two types of arm races :- (1.) Symmetric arm race – when competers seek for same thing and (2.) Asymmetric arm race – when competers seek for different things.
In chapter 8 , Dawkins talks about feedback system. A feedback system is a system where the output is connected back to the system as an input. There are two types of feedback systems: Negative and positive feedback system. In a negative feedback system, the amount of feedback input is decreased as the output is increased. It is very useful to have a control the system at an optimal level.  On the other hand, the feedback input in a positive feedback system is increased as the output is increased.. The input acquires even with a small increase in output. It is this acquiration which will lead to explosion in the end.
Arm races can be stopped economically.If arm races help animals evolve constantly, we should have seen cheetahs which can run at the speed of sound already. We have not. So, what does stop cheetahs to evolve to be better runners?
It is the Economics. If cheetahs had bigger muscles to let them run faster then the muscles would consume more energy. Cheetahs would not then have enough energy to do other activities like producing milk for their youngs. So thus the evolution stops when the benefit of arm races becomes uneconomical.
One important note is that most of the time preys will develop more ability for arm races. This happens because preys need to run for their life while predators just have to run for their dinner.
In chapter 9 ,the author talks about the concept of gradualism, punctuationism, macro mutation, paleontologist, evolutionists and speciation. For evolutionists the approaches to evolution are :- “Gradualism” and “Punctuationism”. In gradualism evolution proceeds slowly and with constant speed while in case of punctuationism it proceeds at any arbitrary time and with variable speed. Punctuationists believe that evolution has two alternating periods. In an evolving period, things evolve appreciably. In a stasis period nothing evolves. Macro mutation happens on very large scale . In case of macro mutation mutants differ very much from original species.Saltation is a kind of macro mutation in which big change happens in one generation.
Punctuationists believe that large population resists change. There are two reasons for this: (1.) Genes in every original individual are working in corporation. There is no need to welcome a new gene to  new corporation and create a mutant.(2.) The group of mutants will be kill to extinction. The mutants evolve from the original population, and tend to have a similar way of life. The original and mutated populations therefore tends to compete rather than co-exist. They kill each other until one of them  becomes extinct. 
Speciation is a subject that deals with how a new species come into existence.
Summary of rate of evolution:- (1.) True saltation: Mutation takes place in one generation on a large scale. (2.)Gradualism, that is anti-true-saltation. (3.) Constant speedism: Evolution happens at constant speed. (4.) Variable speedism: Evolution happens but not necessarily at the constant speed. There are two types:(1)Discrete variable speedism: The rate of evolution at a particular time can be one of several values. (2)Continuous variable speedism: The rate of evolution can fluctuate to any value.
In chapter 10, the author talks about one true tree of life. Taxonomy is a subject that deals with classification of living things. Cladistic Taxonomy is a hierarchical classification. Each node in hierarchy represents species. Upper levels represent ancestors and lower levels represent descendants. 
Parsimony Principle :- Parsimony in the sense of fitting species to a taxonomical tree means the ‘best fit’. The parsimony principle here is in the sense that the difference from the cladistic tree must be as stingy as possible. Taxonomy is thus a science of classification .
Biological taxonomy can be based on various criteria. But, the single way which stands out is based on evolution relation. It is called ‘cladistic taxonomy.’
Types of Taxonomists :- 1. Phyletics:- find a family tree based on evolutionary relationships. Subgroups :- (1.) Cladists :- deals with branching of trees. (2.)Traditionalists :- deals with amount of change at each branch point.
2. Pure-resemblance measurers: finds resemblance tree based on similarity in pattern. Subgroup :- (1.) Pheneticists (2.) Transformed cladists.
In the last chapter Dawkins examines all theories of life on earth, theories that can be considered as rivals to Darwinian theory of evolution by natural selection. From Lamarckianism through mutationism and neutralism to creationism, Dawkins makes detailed examination of each theory and finds none even come close to Darwin’s theory in explaining complexity and design of natural life as exists today on Earth.