Natural selection in action: Darwin's finches

0:00Can we actually watch natural selection happen in the wild?

0:05These are ground finches, a kind of Darwin's finch from the Galápagos Islands.

0:10Their beaks are not all the same size: some are small, and some are large.

0:16They eat seeds, some small and soft, and some big and hard.

0:22Then a long drought came, and the small, soft seeds ran out.

0:27Finches with bigger beaks could crack the big, hard seeds more easily.

0:32Many finches with smaller beaks could not get enough food, and died.

0:37So finches with bigger beaks were more likely to survive.

0:42The survivors had young, and the young had beaks like their parents.

0:47So in the next generation, more finches had large beaks.

0:52Scientists measured real finches after a drought, and saw this happen.

0:58This is natural selection: the finches best suited to the hard seeds survived and passed on their traits.

1:05The drought favoured big beaks, so big beaks became more common.