30 plz answer ! what did peter and rosemary grant conclude?

Peter Raymond Grant, FRS, FRSC, and Barbara Rosemary Grant, FRS, FRSC, are a British couple who are evolutionary biologists at Princeton University. Each currently holds the position of emeritus professor. They are known for their work with Darwin's finches on Daphne Major, one of the Galápagos Islands. Since 1973, the Grants have spent six months of every year capturing, tagging, and taking blood samples from finches on the island. They have worked to show that natural selection can be seen within a single lifetime, or even within a couple of years. Charles Darwin originally thought that natural selection was a long, drawn out process. The Grants have shown that these changes in populations can happen very quickly.

The Grants studied the evolution of Darwin's finches on the Galapagos Islands, they documented environmental changes and how these changes favored certain individuals within the population. The Grants concluded that the offspring of the birds that survived the 1977 drought tended to be larger, with bigger beaks. So the adaptation to a changed environment led to a larger-beaked finch population in the following generation.