In the early 1800s Darwin studied different kinds of finches. What did Darwin hypothesize about these birds?

In the early 1800s, Charles Darwin studied finches on the Galápagos Islands and hypothesized that these birds had evolved from a common ancestor, adapting to different environments and food sources. He proposed that the variations in their beak shapes were a result of natural selection, where those with beaks suited to their specific diets had a survival advantage. This observation helped lay the groundwork for his theory of evolution by natural selection.