THE GOLDEN MEAN

How much number theory does a pine cone need to know? The pictured pine cone has 8 left-handed spirals and 13 right-handed. Count them . The growth patterns of pine cones, sunflowers, and pineapples follow the Fibonacci sequence of numbers: 2, 3, 5, 8, 13, etc. These numbers obey the simple addition rule that each number is the sum of two preceding numbers: 5=2+3, 8=5+3, 13=8+5, etc. The ratio of the consecutive terms of the Fibonacci sequence, 2/3, 3/5, 5/8, 8/13, etc. approaches a ratio called the Golden Mean. Structures whose proportions are in this ratio have been admired for their harmony since classical times.