1.   The cactus ground finches have long beaks for eating seeds and cactus pulp.

2.   The family tree then bushes out into the six species of ground finch and the six tree finches.

3.   The sharp-beaked ground finch picks ticks off iguanas.

4.   Ground finches mostly eat small seeds, and their beaks have adapted to that purpose.

5.   Most female cactus finches starved, and the males mated with some ground finches.

6.   The Grants said that over time the beaks of the cactus finches became blunter, more like those of the ground finches.

7.   This process put genes from the ground finches into the gene pool of the cactus finches.