Great IdeasNature and science
Evolution and the history of life
How living things change over long ages.
The question
Have living things always been the way they are, or have they changed over long ages? How?
How the books answer
Oldest first. Each stop is our own short summary of what the author argued; follow the link to the rung for the whole lesson.
c. 350–322 BC
Aristotle, Physics
Aristotle reports an older idea from Empedocles: that long ago animals came together by chance, and only the well-fitted ones survived. He rejects it. Living things, he argues, grow according to purpose, since their parts are too regularly fitted to be mere chance.
c. 55 BC
Lucretius, On the Nature of Things (in the set: The Way Things Are)
Lucretius writes that the earth once produced many strange creatures, and those that could not feed, defend themselves and have young died out. It is not evolution as Darwin meant it, since species did not change into new ones, but it is an early idea of nature weeding out the unfit.
1859
Charles Darwin, On the Origin of Species
Darwin gathers evidence from breeders, fossils, islands and the shapes of living things. He argues that species change over many generations by natural selection: helpful variations are kept, harmful ones lost. He admitted gaps in the evidence and answered objections at length.
“This preservation of favourable variations and the rejection of injurious variations, I call Natural Selection.”
1871
Charles Darwin, The Descent of Man
Darwin applies his theory to human beings, arguing that people share ancestors with other animals. He spends much of the book on how moral sense and kindness could develop. He calls conscience the most important difference between humans and other animals.
“I fully subscribe to the judgment of those writers who maintain that of all the differences between man and the lower animals, the moral sense or conscience is by far the most important. ...”
1937
Theodosius Dobzhansky, Genetics and the Origin of Species
Dobzhansky joins Darwin's theory with the new science of genes. He shows how variation, inheritance and selection work in wild populations, especially fruit flies. His book helped build what is called the modern synthesis.
Go to the rung: Dobzhansky: Genetics and the Origin of Species
1961
C. H. Waddington, The Nature of Life
Waddington asks how development and evolution fit together. Changes in how an embryo grows, he argues, are what natural selection works on. He wanted biology to explain both the history of life and the growth of each living thing.
For young readers
Long ago there were dinosaurs, giant ferns and woolly mammoths. Today there are different animals. Charles Darwin studied how living things change over very long times.
He noticed that animals have babies that are a little different from each other. The ones best suited to their home, like a bird whose beak fits the seeds nearby, tend to survive and have more babies. Over many, many generations, that adds up to big changes. People hold different beliefs about how this fits with faith, and families can talk about that together.
Talk about it
- Look at pictures of dogs of different breeds. How did people make them so different?
- Why might a white rabbit survive better in snowy places?
- Darwin said conscience was the most important difference between people and animals. What do you think?
- How do fossils help us learn about the past?
Where else on the site
- Natural Selection
- Natural Selection
- How New Species Form
- Evidence: Fossils and Anatomy
- Mendel's Experiments
- Hardy-Weinberg Equilibrium
Every rung tagged with this idea:
These pages are our own short synthesis, written for families. They were inspired by Mortimer J. Adler's Syntopicon, the index of great ideas in volumes 1 and 2 of Great Books of the Western World, but the questions, summaries and groupings are ours, not the Syntopicon's. Short excerpts come from public-domain translations, credited where they appear.