What Really Happened: Darwin's Finches

The Authorea Team

Finches are often thought to be the key to Charles Darwin's theory on evolution. These birds were present on the Galapagos Islands when Darwin visited. They varied in size and (perhaps most memorably to grade school evolutionary biology enthusiasts and textbooks) beak shape--seemingly different species of finches appeared on the different islands. Often credited with the inspiration for Darwin's idea of descent with modification, finches are a famous example of Darwin's theories in action... But how much credit do they really deserve? 
In fact, finches aren't even mentioned in On the Origin of Species. While the finches are covered in his journal, he seemed to be largely confused by the appearance of the finches on the different islands. He speculated that the finches might have come from one common ancestor, but never finalized an evolutionary hypothesis based on these birds.

Additionally, he barely tracked said finches on the islands--he didn't label where he found the specimens he took, hardly spent time observing their diets, and was confused by the significance of their beak types. He didn't know enough about the finches to cite them in his book, and they definitely didn't convince him of evolution.
source: Quasarex
Many textbooks today credit these finches to Darwin's theories, perhaps because Darwin had mentioned them in another book (his Journal)-- not his famous On the Origin. Although Darwin himself didn't even collect these finches, science history has used these birds as an easy example to explaining evolution.

The bird that truly sparked Darwin's theories was the mockingbird. #ohtheirony