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Book Summary: The Greatest Show on Earth by Richard Dawkins

My Personal Summary

This book is about why evolution is true.

Evolution is the process of genes randomly mutating and beneficial mutations becoming more and more common in the gene pool of a species because they help organisms survive better.

The change in a species appearance from one generation to the next is so small it’s not noticeable but over the course of millions of years it becomes noticeable.

Book Notes

  • Evolution is the process of genes randomly mutating and beneficial mutations becoming more and more common in the gene pool of a species because they help organisms survive better.
  • The change in a species appearance from one generation to the next is so small it’s not noticeable but over the course of millions of years it becomes noticeable.
  • The same way people breed dogs for certain traits and appearances, nature also breeds animals characteristics in such a way that the ones who develop random helpful mutations have a better chance of surviving and thus pass on their genes for those traits to their offspring.
  • When humans breed animals or plants, it’s known as artificial selection. When nature breeds them via who does and doesn’t survive, it’s called natural selection.
  • Humans are cousins of monkeys, not descendants of monkeys. They share a common ancestor.
  • There is a phenomenon called pleiotropy where gene traits develop together and one that may seem “useless” (like the fact that tame dogs who can get food more easily from humans also tend to develop floppy ears) may actually have no Darwinian benefit. It’s just a result of pleiotropy.
  • If we can breed dogs for certain traits and go from wolves to various dog breeds in just a couple centuries via artificial selection, it shouldn’t be hard to imagine that species can evolve and change dramatically over the lifetime of the universe (4.6 billion years)
  • A 20-year experiment at Michigan State University showed that random mutations in colonies of bacteria can allow them to survive better and develop abilities to ingest citrate, which improves their ability to survive and grow. This is a mini version of evolution that occurred in just years.
  • Another experiment showed that fish will change colors through different generations in different ponds based on which color is more suitable for survival from predators. This was the most important study in the book for me – fish literally changed appearance in a matter of years just based off which predators were put in the ponds. This is natural selection on a tiny time scale.
  • Differences in genes cause differences in the development of organisms, and the environment determines which differences enable an organism to survive better. This means those genes that enhance survival ability become more common in the gene pool. This is natural selection.
  • Differences in genes exist because when cells split during the creation of an embryo, they split asymmetrically and thus the resulting organisms are shaped slightly differently even within the same species.
  • Many species split in their evolutionary tree due to geographical differences that cause differences in the environments and thus the gene pools. The most famous of this is the Galápagos Islands located 600 miles west of South America, in which similar species are notably different between the islands. Tortoises on each island are shaped differently in such ways to maximize their chances of survival on those particular islands.
  • Through freak storms or other means, animals can be carried to different islands where, once isolated, develop into their own species via natural selection. Frogs are not found on any major islands because they are killed by salt water.
  • All of the continents used to be connected together as Pangea, but plate tectonics have caused them to separate, which represents the greatest historical separation and isolation of different species, which went on to develop in unique ways.
  • There are various computer methods that can be used to compare genes between species, which allows us to understand how similar different species are and also how recently different species shared a common ancestor. This allows us to build a massive family tree of all living species.

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