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Learn Evolution

The idea that makes sense of all of biology, explained one step at a time.

Free to start. Built from a single prompt. No credit card.

Evolution is the change in inherited traits of populations over generations, and natural selection, described by Charles Darwin and Alfred Russel Wallace, is its best known mechanism. It explains why bacteria become resistant to antibiotics, why whales have finger bones in their flippers and why all life shares one genetic code. Learning it well means understanding the mechanisms (selection, drift, mutation and gene flow), the evidence and how to read evolutionary trees. Learnr builds a personalized evolution course from a single prompt and teaches it through short, interactive lessons.

How to learn Evolution, step by step

Understand natural selection in three conditions. Selection happens whenever individuals vary, the variation is heritable and some variants leave more offspring. Apply it to Galapagos finch beaks during drought years and to bacteria exposed to antibiotics until you can explain both in your own words.
Learn the main lines of evidence. Study transitional fossils like Tiktaalik and early whales, homologous structures such as the bones in a human arm and a bat wing, vestigial traits, island biogeography and the DNA similarities between related species.
Add the other mechanisms of change. Learn genetic drift and why it is strongest in small populations, including bottlenecks and founder effects. Then add mutation as the source of new variation and gene flow as the mixing of populations, using Hardy-Weinberg as the no-evolution baseline.
Study adaptation and its limits. Learn sexual selection, like the peacock's tail, and trade-offs between traits. See why evolution produces workable rather than perfect designs, such as the vertebrate eye's blind spot, because it can only modify what already exists.
Learn to read phylogenetic trees. Practice reading trees by their branch points, not by the order of tips. Two species are most closely related when they share the most recent common ancestor, and no living species is an ancestor of another living species.
Explore speciation and deep history. Compare allopatric and sympatric speciation and the barriers that keep species apart. Then survey major transitions like the origin of eukaryotes and the move onto land, keeping terms fresh with short daily Learnr lessons.

What you'll learn

Explain natural selection using variation, inheritance and differential reproduction
Compare selection, genetic drift, mutation and gene flow
Evaluate evidence from fossils, anatomy, biogeography and DNA
Read phylogenetic trees and identify common ancestors correctly
Explain how new species form through reproductive isolation

What's inside your Evolution course

A sample path Learnr builds for Evolution. Your real course adapts to your goal and level.

1. Darwin, Wallace and the idea of natural selection
2. The evidence for evolution
3. Population genetics and the mechanisms of change
4. Adaptation and sexual selection
5. Speciation and phylogenetic trees
6. Major transitions and human evolution

How long does it take to learn Evolution?

The core ideas and evidence take about 6 to 10 weeks at 3 hours a week. A university-level evolution course with population genetics and phylogenetics takes a semester, and genetics and statistics background speeds up the quantitative parts.

What you need before you start

Basic biology and an introduction to genetics, including genes, alleles and how traits are inherited. Learnr can add a short genetics primer to the start of your course.

Common mistakes to avoid

Thinking individuals evolve or that organisms change because they need to. Populations change as heritable variants that already exist become more or less common.
Reading evolution as a ladder with humans at the top. Every living species is equally evolved, and the tree branches rather than climbing.
Saying humans evolved from chimpanzees. Humans and chimpanzees share a common ancestor that was neither, and both lineages kept evolving.

How Learnr builds your course

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Evolution questions, answered

Is evolution just a theory?

In science a theory is a well-tested explanation supported by many lines of evidence, not a guess. Evolution is supported by fossils, anatomy, DNA comparisons and directly observed change in populations.

Can we see evolution happening today?

Yes. Antibiotic resistance in bacteria, pesticide resistance in insects and long-term experiments on bacteria and finch populations show measurable evolutionary change within human lifetimes.

How does genetics relate to evolution?

Genetics explains how traits are inherited and where new variation comes from. Evolution describes how the frequencies of those inherited variants change in populations over generations.