This afternoon I spent about 4.5 hours in a coffee shop reading this book. I was very dizzy but knowing that sleep when sitting is not good for your heart and brain so I just tried every effort to keep myself awake.
The title of this chapter is 'Chance, Change and Evolution'. it discusses the lifecycle of a species: evolution, survival, and extinction. Evolution here is forming a new species, when the genetic change is profound enough. The definition of 'species' is that the population is reproductively isolated.
Chance events play important parts in evolution.
Life formed in primitive oceans. The organic molecule's forming from inorganic materials is a small-probability event but it will occur giving enough reaction chances. The early life utilize sulfuret and energy from sun or earth to produce CH_2O.
There has been much more life forms in certain periods than today, for example, Cambrian. Many species extincted in the past. In fact, extinction is part of the history of life on the earth. Human is *not* the most advanced form of life. We are just lucky enough to survive. And we are just a twig of the species bush.
The life of a species may be from 4 million to 22 million years. Every species will extinct, sooner or later. In the past, it's meteroids' impact accelarating this process. Now it's human doing the same job.
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