Want to learn the ideas in On the Origin of Species better than ever? Read the world’s #1 book summary of On the Origin of Species by Charles Darwin here.

Read a brief 1-Page Summary or watch video summaries curated by our expert team. Note: this book guide is not affiliated with or endorsed by the publisher or author, and we always encourage you to purchase and read the full book.

1-Page Summary of On the Origin of Species

Overview

Darwin’s theory of evolution is one of the most important scientific discoveries in history. Many people believe that God created all species separately and exactly as they are, but Darwin believed that all species descend from common ancestors and transformed over time. Today we have new ways to understand genetics, which fill in gaps in his knowledge.

In this passage, you’ll learn how to explain instinct through natural selection and why pigeon breeding is related to it. You’ll also see how humans, moles and bats share similarities in their bones because of natural selection.

Big Idea #1: Domesticated animals were created by humans.

Domestic breeds are created through human selection.

Different species of animals have evolved into different breeds, but they all came from the same ancestor.

The various breeds of domestic pigeons descended from the rock pigeon. People have been breeding them for thousands of years, and they’ve gotten very good at it. For example, Sir John Sebright bred pigeons that were any color or pattern in a few years. The process is called selection.

Breeds are distinguishable by features called variations. For example, pugs have short noses. To make a breed like that, you would take a group of dogs and select the ones with the shortest noses and mate them. You’d do this for several generations until they had shorter noses than before, until eventually you’d have pugs.

Most people are not aware of how they select mates. They tend to choose the mate that is closest to them, which can lead to shocking results.

Imagine a pigeon breeder who breeds pigeons with longer tails. Because of this, the structure of their tail bones changes over time and eventually transforms into that of a peacock’s.

Big Idea #2: Nature has probably selected traits that help organisms survive, which may have formed different species over many generations.

What if nature could breed organisms with certain traits and create new species?

A process called natural selection could explain the existence of similar species. For example, horses, zebras and donkeys would all descend from a common ancestor over many generations. Natural selection determines which species survive and which perish in this long process. All living creatures struggle for survival because they’re constantly competing with each other for food, shelter or any advantage that will help them to live another day.

So, what determines whether an organism lives or dies? It all depends on their variations. If they have a beak that’s hard enough to get them food, then they’ll survive. For example, imagine you’re a bird and you need to find food in order to live. You might try pecking at the bark of trees because there may be insects underneath the bark.

Because of that, you have an advantage over your siblings. You get to eat food from a private source while they starve. This allows you to survive and pass on the trait of having a hard beak to your offspring. They would then also have an advantage over their siblings because they are able to eat food with their harder beaks.

Over time, birds with increasingly harder beaks were produced. Eventually, this resulted in a woodpecker’s incredibly hard beak. This process of evolution is called descent with modification.

Big Idea #3: Sexual selection also contributes to natural selection.

In summary, nature selects organisms with different advantages that are passed on to their offspring. This is how we get new species and how they evolve over time.

Sexual selection is another factor that explains variations. This happens because, in addition to having to compete for survival, male animals also have to compete for the attention of females. In turn, female animals choose mates with characteristics they find attractive and these characteristics become established over generations. For example, take turkeys; female turkeys might prefer males with droopy neck skin and this preference leads to a gradual increase in the size of the neck skin until it forms their characteristic wattle.