In an extensive genetic study, Charles Darwin's Galapagos Island finches have been revealed to have a strange and complicated evolutionary history.

According to BBC News, authors of a study published in the journal Nature sequenced the genomes of 120 different birds of 17 species. Darwin supported his Theory of Natural Selection with the finches, as their beaks evolved to better consume the food around them.

"This is an interesting example where mild mutations in a gene that is critical for normal development leads to phenotypic [observable] evolution," lead researcher Leif Andersson, a professor of functional genomics at Uppsala University, the Swedish University of Agricultural Sciences, said in a press release.

Assisting Andersson in the study, among others, was Peter Grant and his wife Rosemary, both professors at Princeton University. They specifically looked for diverse beak shapes in Darwin's finches and identified a gene called ALX1, which was linked to differing beaks within one species.

"What we discovered is basically two variants of ALX1," Andersson told BBC News. "One is associated with pointed beaks - that is the ancestral form. Then there is a variant associated with the blunt beaks. That's the derived form.

"The blunt beak version is a genetic innovation that occurred on the islands."

In sifting through the finches' evolutionary history, the team learned the birds often interbred, which could very well have contributed to their beak evolution.

"This is a very exciting discovery for us," Rosemary Grant told BBC News. "We have previously shown that beak shape in the medium ground finch has undergone a rapid evolution in response to environmental changes. Now we know that hybridization mixes the different variants of an important gene, ALX1."